CN101471636B - Variable Gain High Dynamic Range Amplifier - Google Patents

Abstract

A variable gain high dynamic range amplifier includes an amplifier module, a control unit and an output current amount adjusting circuit. The amplifier module is used for amplifying an input signal and comprises a plurality of amplifier units, the amplifier units are coupled in parallel, and the gain values of the amplifier units are different. The control unit is used for enabling at least one of the plurality of amplifier units according to a gain control signal, and the enabled at least one amplifier unit is used for responding to the input signal to output a current signal. The output current amount adjusting circuit is used for receiving the current signal output by the enabled at least one amplifier unit and adjusting the magnitude of the current signal under the control of the control unit so as to correspondingly output an output signal. Wherein each amplifier unit is coupled in series with the output current amount adjusting circuit.

Description

Variable Gain High Dynamic Range Amplifier

technical field

The present invention relates to an amplifier, and more particularly to a variable gain high dynamic range amplifier.

Background technique

In the field of communication, receivers used to receive signals often use dynamic amplifiers to amplify the received signals. When the amplitude of the received input signal changes, the gain of the dynamic amplifier will change accordingly to maintain the magnitude of the output signal.

Please refer to FIG. 1 , which shows a circuit diagram of a conventional dynamic amplifier using a current steering circuit. The dynamic amplifier 100 uses the current driver 140 to adjust the gain of the dynamic amplifier 100 according to the voltage of the control signal V _CTL . When the amplitude of the input signal Vi becomes larger, the voltage of the control signal V _CTL becomes lower to reduce the magnitude of the output current i _o to reduce the gain of the dynamic amplifier 100 . However, when the amplitude of the input signal Vi is too large, the transistors Q ₁₂₁ and Q ₁₂₂ of the differential amplifier 120 will operate in a saturation region, causing the output signal to be distorted. Therefore, even if the magnitude of the output current i _o is reduced at this time, the problem of waveform distortion of the output current i _o cannot be solved. Therefore, the conventional dynamic amplifier 100 has the disadvantage that the linearity is not large enough to meet the desired requirements. The linearity here refers to the range of the amplitude of the input signal so that the output signal will not be distorted.

In order to improve the linearity, a traditional dynamic amplifier using a degenerating resistance circuit to adjust the gain (DegeneratingResistance Tuning) is proposed, and its circuit diagram is shown in Figure 2. The degenerative resistance circuit is realized by a metal oxide semiconductor field effect transistor (MOS transistor). The dynamic amplifier 200 uses the gate control voltage V _CTL ′ of the field effect transistor 240 to change the equivalent resistance value when the field effect transistor 240 is turned on, so as to adjust the gain of the dynamic amplifier 200 . In this way, the range of the acceptable amplitude of the input signal Vi without distortion of the output signal of the dynamic amplifier 200 can be increased, so as to improve the dynamic range of the dynamic amplifier 200 . Since the gain of the dynamic amplifier 200 is related to the impedance value of the field effect transistor 240, however, when the frequency of the input signal Vi is too high, the influence of the parasitic capacitance of the degeneracy resistor circuit on the gain will increase, so that the dynamic amplifier 200 will operate at high frequencies. The gain value at this time cannot be precisely adjusted. At the same time, the linearity of the dynamic amplifier 200 is difficult to control when receiving high-frequency input signals.

In addition, a high dynamic range radio frequency receiver (Radio Receiver With Wide Dynamic Range) is also proposed in US Patent No. 3,728,633. Its receiver system includes two receivers, the first receiver is controlled by AGC bias (AGC bias), and the second receiver is controlled by delayed AGC (Delayed AGC). When the input signal level (signal input levels) is bigger, the level of AGC is bigger. When the AGC reaches a cross-over point (Cross-Over Point), the gain of the first receiver is zero, and the second receiver starts to function. This receiver system uses AGC bias and delayed AGC to switch the two receivers without using switches.

And U.S. Patent No. 5,625,321 also proposes a variable gain amplifier device (Variable Gain Amplifier Apparatus), which uses two variable gain amplifiers (variable gain amplifier). The gain ratio of the two variable gain amplifiers has a complementary relation and is controlled by the same gain control signal. When the gain value of one variable gain amplifier becomes larger, the gain value of the other variable gain amplifier becomes smaller.

In order to solve the above-mentioned problem that the linearity of the dynamic amplifier 200 is difficult to control, US Patent No. 6,049,251 also discloses a high dynamic range variable gain amplifier circuit (Very-Wide-Range Variable-Gain Amplifier). As shown in Fig. 3A, it shows the circuit diagram of the above-mentioned high dynamic range variable gain amplifier. The high dynamic range variable gain amplifier includes two amplifier circuits 320 and 340 . Please refer to FIG. 3B and FIG. 3C , which respectively show detailed circuit diagrams of the amplifier circuits 320 and 340 . The resistance value of R _E1 in FIG. 3B is small, so the amplifier circuit 320 has high gain and low linearity. The resistance value of R _E2 in FIG. 3C is large, so the amplifier circuit 340 has a low gain value and high linearity. The amplifier circuits 320 and 340 are coupled in parallel, and their gain values are controlled by automatic gain control signals AGC1 and AGC2 respectively. Since the amplifier circuits 320 and 340 have different gains, two amplifiers with different linearities can be achieved, thereby improving the dynamic range.

However, if the range of the acceptable input signal is to be further improved, at least one amplifier circuit needs to be connected in parallel. At this time, the required components will be increased, the cost will be increased accordingly, and the complexity of the entire circuit will be increased. Therefore, how to increase the range of the input signal that the amplifier can receive without increasing the complexity of the circuit is one of the issues that the industry is working on.

Contents of the invention

The purpose of the present invention is to provide a variable gain high dynamic range amplifier, which can increase the dynamic range of the amplifier, reduce the required circuit components and reduce the complexity of the circuit.

To achieve the above object, the variable gain high dynamic range amplifier provided by the present invention includes:

An amplifier module, used to amplify an input signal, the amplifier module includes a plurality of amplifier units, the amplifier units are coupled in parallel, and the gain values of the amplifier units are different;

a control unit for enabling at least one of the amplifier units according to a gain control signal, and the enabled at least one amplifier unit is used for outputting a current signal in response to the input signal; and

An output current adjustment circuit, used to receive the current signal output from the enabled at least one amplifier unit, and under the control of the control unit, adjust the magnitude of the current signal to output an output signal correspondingly , each amplifier unit is coupled in series with the output current regulating circuit;

Wherein, the control unit controls the output current regulating circuit according to the gain control signal.

The variable gain high dynamic range amplifier, wherein the gain control signal corresponds to the magnitude of the input signal, and the control unit includes:

A pre-segmentation unit is used to receive the gain control signal, and correspondingly output a plurality of enable signals according to the magnitude of the gain control signal to respectively enable the amplifier units, the pre-segmentation unit is used to The gain control signal generates a segment adjustment control signal, and the output current adjustment circuit adjusts the magnitude of the current signal according to the segment adjustment control signal. When the gain control signal increases or decreases linearly with time, the segment adjustment The waveform of the control signal on the time axis is substantially a sawtooth wave.

In the variable gain high dynamic range amplifier, the sawtooth wave is a sawtooth wave with hysteresis.

The variable gain high dynamic range amplifier, wherein the pre-segmentation unit includes:

an analog/digital converter for converting the gain control signal into a first signal;

a digital/analog converter for converting the first signal into a second signal; and

A subtractor is used for subtracting the second signal from the gain control signal to generate the section adjustment control signal.

In the variable gain high dynamic range amplifier, the control unit further includes a unit converter for adjusting the size of the section adjustment control signal, and the output current adjustment circuit is adjusted according to the section adjustment control signal to adjust the size of the current signal.

The variable gain high dynamic range amplifier, wherein the amplifier module includes:

a first amplifier circuit, including a first differential amplifier, for amplifying the input signal;

A second amplifier circuit comprising:

a current source unit;

a second differential amplifier for amplifying the input signal, the second differential amplifier being coupled to the current source unit; and

A first resistor module, coupled to the second differential amplifier, the first resistor module includes a plurality of main resistors and a plurality of main switches, each of which is selectively controlled by the control unit ground conduction, the main switch being turned on is used to make the corresponding main resistor have a current path, and the gain value of the second differential amplifier is related to the resistance value of the main resistor with the current path; and

a selection unit, used to enable one of the first differential amplifier and the second differential amplifier under the control of the control circuit, so that the enabled first differential amplifier and the second differential amplifier One of the two amplifiers outputs the current signal corresponding to the input signal.

The variable gain high dynamic range amplifier, wherein the first differential amplifier has a first transistor and a second transistor, the bases of the first transistor and the second transistor are used to receive the input signal, the The emitters of the first transistor and the second transistor are both coupled to ground voltage;

Wherein, the current source unit includes a first current source and a second current source, the second differential amplifier includes a third transistor and a fourth transistor, and the main resistors include a plurality of first main resistors and A plurality of second main resistors, the bases of the third transistor and the fourth transistor are used to receive the input signal, the emitters of the third transistor and the fourth transistor are respectively coupled to the first current source and the first current source A second current source, the emitter of the third transistor is also coupled to the first main resistors, the emitter of the fourth transistor is also coupled to the second main resistors, each first main resistor electrically connected to a second main resistor through a main switch;

Wherein, the collectors of the first transistor and the second transistor are respectively coupled to the collectors of the third transistor and the fourth transistor, and the collectors of the first transistor and the second transistor are used to output the current signal.

The variable gain high dynamic range amplifier further includes a signal input terminal, a DC bias isolation circuit and a bias circuit, the signal input terminal is used to receive the input signal, and the DC bias isolation circuit is coupled to Connected between the signal input end and the amplifier module, the bias circuit is used to provide a DC bias voltage to the amplifier module.

The variable gain high dynamic range amplifier, wherein the DC bias isolation circuit includes four capacitors, one end of the four capacitors is coupled to the signal input end, and the other ends of the four capacitors are respectively coupled to the The bases of the first transistor, the second transistor, the third transistor and the fourth transistor, the bias circuit is used to provide a DC bias to the first transistor, the second transistor, the third transistor and the fourth transistor bases of four transistors.

The variable gain high dynamic range amplifier, wherein the amplifier module further includes a second resistor module including a plurality of first auxiliary resistors, a plurality of second auxiliary resistors and a plurality of auxiliary switches, the third The base of the transistor is also coupled to the first auxiliary resistors, the base of the fourth transistor is also coupled to the second auxiliary resistors, and each first auxiliary resistor is connected to the first auxiliary resistor through an auxiliary switch. The two auxiliary resistors are electrically connected.

The variable gain high dynamic range amplifier, wherein the output current adjustment circuit includes a fifth transistor, a sixth transistor, a seventh transistor and an eighth transistor, the sixth transistor and the seventh transistor The collectors are electrically connected to a supply voltage, the emitters of the fifth transistor and the sixth transistor are electrically connected to the collectors of the first transistor, and the emitters of the seventh transistor and the eighth transistor are coupled to To the collector of the second transistor, the base of the fifth transistor is electrically connected to the base of the eighth transistor, the base of the sixth transistor is electrically connected to the base of the seventh transistor, the fifth the voltages of the transistor and the base of the sixth transistor are controlled by the control unit;

Wherein, the collectors of the fifth transistor and the eighth transistor are used to output the output signal.

The variable gain high dynamic range amplifier, which also includes a matching unit, when the input signal is a single-ended input signal, the matching unit is used to convert the single-ended input signal into a double-ended input The input signal of the first differential amplifier and the second differential amplifier are used to amplify the input signal of double-terminal input.

The variable gain high dynamic range amplifier provided by the present invention can achieve the advantages of improving the dynamic range of the amplifier and simplifying the circuit by coupling a plurality of amplifier units with different gain values in parallel and sharing the current adjustment circuit. In addition, by using the DC bias isolation circuit, the effect of fast switching between different amplifier circuits is achieved.

Description of drawings

Figure 1 shows the circuit diagram of a conventional dynamic amplifier using a current driver.

Figure 2 shows the circuit diagram of a conventional dynamic amplifier that uses a degenerate resistor circuit to adjust the gain.

FIG. 3A shows a circuit diagram of the high dynamic range variable gain amplifier circuit of US Patent 6,049,251.

3B-3C show circuit diagrams of amplifier circuits 320 and 340 in FIG. 3A, respectively.

FIG. 4 shows a system block diagram of a variable gain high dynamic range amplifier according to an embodiment of the present invention.

FIG. 5 shows an example of a detailed circuit diagram of the variable gain high dynamic range amplifier of FIG. 4 .

FIG. 6 shows an example of a circuit diagram of the pre-segmentation unit in FIG. 5 .

7A-7D show an example of the waveform diagrams of the gain control signal VC and the segment adjustment control signal VCseg of the pre-segmentation unit in FIG. 6 .

FIGS. 8A and 8B respectively show the segment adjustment control signal VCseg with a hysteresis sawtooth waveform corresponding to the gain control signal VC of FIGS. 7A and 7C .

Explanation of main component symbols in the attached drawings:

100: Dynamic amplifier

120, 220: Differential amplifier

Q ₁₂₁ , Q ₁₂₂ , Q ₂₂₁ , Q ₂₂₂ , Q1～Q8: transistors

140: current driver

240: Degenerate Resistor Circuit

320, 340, 520, 540: amplifier circuit

400, 500: Variable Gain High Dynamic Range Amplifiers

420: Amplifier Module

422: Amplifier Unit

440: Control unit

460: output current adjustment circuit

501: Signal input terminal

502: Current Mirror

510: Matching unit

530: DC bias isolation circuit

543: Resistor Module

550: Bias circuit

570: Resistor Module

580: Pre-segmentation unit

590: Unit Converter

620: Analog/Digital Converter

640: Digital/Analog Converter

660: Subtractor

680: Amplifier Unit Selection Circuit

C1, C2, C3, C4: Capacitors

CS1, CS2: current source

R1, R2: main resistors

R3, R4: auxiliary resistors

SW1, SW2: enable switch

SW3: Main switch

SW4: Auxiliary switch

Detailed ways

The variable gain high dynamic range amplifier of the present invention includes an amplifier module, a control unit and an output current adjustment circuit. The amplifier module is used to amplify an input signal. The amplifier module includes a plurality of amplifier units connected in parallel, and the gain values of the amplifier units are different. The control unit is used for enabling at least one of the amplifier units according to a gain control signal. The enabled at least one amplifier unit is used to output a current signal in response to the input signal. The output current adjustment circuit is used for receiving the current signal output from at least one enabled amplifier unit, and under the control of the control unit, adjusts the magnitude of the current signal to output an output signal correspondingly. Each amplifier unit is coupled in series with the output current regulating circuit.

In order to make the above content of the present invention more obvious and easy to understand, a preferred embodiment is given below, and it is described in detail in conjunction with the accompanying drawings as follows:

Please refer to FIG. 4 , which shows a system block diagram of a variable gain high dynamic range amplifier according to an embodiment of the present invention. The variable gain high dynamic range amplifier 400 shown in FIG. 4 includes an amplifier module 420 , a control unit 440 and an output current adjustment circuit 460 . The amplifier module 420 is used for amplifying the input signal Vi. The amplifier module 420 includes a plurality of amplifier units 422 . The multiple amplifier units 422 are coupled in parallel, and the gain values of the multiple amplifier units 422 are different. The control unit 440 is used for enabling at least one of the plurality of amplifier units 422 according to the gain control signal VC. The enabled at least one amplifier unit 422 is used to output a current signal Io in response to the input signal Vi. The output current adjustment circuit 460 is used for receiving the current signal Io output from at least one enabled amplifier unit 422 , and under the control of the control unit 440 , adjusts the magnitude of the current signal Io to output an output signal Out accordingly. Each amplifier unit 422 is coupled in series with the output current regulating circuit 460 . The control unit 440 controls the output current adjustment circuit 460 according to the gain control signal VC.

In this embodiment, by using a plurality of amplifier units 422 coupled in parallel, the control unit 440 selects different amplifier units 422 under the control of the gain control signal VC, so that the output signal Out of the amplifier 400 can be improved so that the output signal Out will not The amplitude range of the distorted input signal Vi can increase the dynamic range of the amplifier 400 . In addition, each amplifier unit 422 of the variable-gain high dynamic range amplifier 400 of the present invention is coupled in series with the output current adjustment circuit 460, so that one output current adjustment circuit 460 can be shared by multiple amplifier units 422, so it can effectively to simplify the circuit. In this way, while realizing a high dynamic range amplifier in this embodiment, the purpose of simplifying the circuit and reducing the circuit components to reduce the cost can also be achieved. In this embodiment, the output current regulation circuit 460 is realized by using a current driver, for example, but it is not limited thereto.

Please refer to FIG. 5 , which shows an example of a detailed circuit diagram of the variable gain high dynamic range amplifier of FIG. 4 . The amplifier module 420 includes amplifier circuits 520 and 540 and a selection unit. The amplifier circuit 520 includes a first differential amplifier for amplifying the input signal Vi. The amplifier circuit 540 includes a current source unit, a second differential amplifier and a resistor module 543 . The second differential amplifier is used to amplify the input signal Vi, the second differential amplifier is coupled to the current source unit, and the resistor module 543 is coupled to the second differential amplifier. The resistor module 543 includes a plurality of main resistors R1 and R2 and a plurality of main switches SW3. Each main switch SW3 is selectively turned on under the control of the control unit 440 , and the turned-on main switch SW3 is used to make the corresponding main resistors R1 and R2 have a current path. The gain value of the second differential amplifier is related to the resistance value of the main resistors R1 and R2 having a current path. The selection unit is used to enable one of the first differential amplifier and the second differential amplifier under the control of the control circuit 440, so that the enabled one of the first differential amplifier and the second differential amplifier outputs The current signal Io corresponding to the input signal Vi.

The variable gain high dynamic range amplifier 500 also includes a signal input terminal 501 and a matching unit 510 . The signal input terminal 501 is used for receiving an input signal Vi. When the input signal Vi is a single-ended input signal, such as a radio frequency (Radio Frequency) signal, the matching unit 510 is used to convert the single-ended input signal Vi into a double-ended differential input signal Vd, and The impedance matching between the input terminal 510 and the lower circuit of the matching unit 510 is completed. The matching unit 510 is implemented, for example, by a single-ended to double-ended converter (Balance to Unbalance Transformer, BALUN). The first differential amplifier and the second differential amplifier process the differential input signal Vd converted from the input signal Vi.

The first differential amplifier of the amplifier circuit 520 has a transistor Q1 and a transistor Q2. The bases of the transistors Q1 and Q2 are used to receive the differential input signal Vd, and the emitters of the transistors Q1 and Q2 are both coupled to the ground voltage. The current source unit of the amplifier circuit 540 includes current sources CS1 and CS2 , and the current sources CS1 and CS2 are implemented by the current mirror 502 . The second differential amplifier includes transistors Q3 and Q4. The bases of the third transistors Q3 and Q4 are used to receive the differential input signal Vd. The emitters of the transistors Q3 and Q4 are respectively coupled to the current sources CS1 and CS2. The emitter of transistor Q3 is also coupled to a plurality of main resistors R1, and the emitter of transistor Q4 is also coupled to a plurality of main resistors R2. Each main resistor R1 is electrically connected to a main resistor R2 through a main switch SW3. The collectors of the transistors Q1 and Q2 are respectively coupled to the collectors of the transistors Q3 and Q4, and the collectors of the transistors Q1 and Q2 are used to output the current signal Io. The selection unit includes, for example, enabling switches SW1 and SW2 , the enabling switch SW1 is electrically connected to the emitters of the transistors Q1 and Q2 , and the enabling switch SW2 is electrically connected to the current mirror 502 . The emitters of the above-mentioned transistors Q1 and Q2 can also be coupled to a current source, but this embodiment is described by taking the emitters of the transistors Q1 and Q2 both coupled to the ground voltage as an example.

The variable gain high dynamic range amplifier 500 further includes a DC bias isolation circuit 530 and a bias circuit 550 . The DC bias isolation circuit 530 is coupled between the signal input terminal 501 and the amplifier module 420 , preferably between the matching unit 510 and the amplifier module 420 . The bias circuit 550 is used to provide a DC bias voltage to the amplifier module 420 . The DC bias isolation circuit 530 includes, for example, four capacitors C1 - C4 . One terminals of the four capacitors C1 - C4 are coupled to the signal input terminal 501 through the matching unit 510 , and the other terminals of the four capacitors C1 - C4 are respectively coupled to the bases of the transistors Q1 - Q4 . The bias circuit 550 is used to provide a DC bias voltage to the bases of the transistors Q1 - Q4 . The capacitors C1-C4 are used to isolate the voltage between the bases of the transistors Q1 and Q2 and the transistors Q3 and Q4 respectively. The DC bias voltage of the bases of the transistors Q1 - Q4 is directly provided by the bias circuit 550 .

The operation of the variable gain high dynamic range amplifier 500 is explained as follows. The control unit 440 outputs switch control signals CSW1 and CSW2 according to the gain control signal VC to respectively control the switches SW1 and SW2 to select at least one of the amplifier circuits 520 and 540 . The gain control signal VC is provided by an external circuit. When the input signal Vi is larger, the gain control signal VC is correspondingly smaller. If the control unit 440 selects the amplifier circuit 540, the control unit 440 also outputs a plurality of enabling signals to control the main switches. In this embodiment, the resistor module 543 includes three main resistors R1 and R2 with different resistance values and three main switches SW3, and the control unit 440 outputs a plurality of enable signals MC1-MC3 to control the main switch SW3 as an example. illustrate. By turning on one of the three main switches SW3, or turning on two or more main switches SW3 at the same time, the resistor module 543 can have various equivalent resistance values. The resistor modules 543 with different equivalent resistance values can make the amplifier circuit 540 equivalent to a plurality of amplifier units 422 with different gains in FIG. 4 .

When the gain control signal VC received by the control unit 440 changes with the magnitude of the input signal Vi, for example, when the amplitude of the input signal Vi becomes larger, the voltage of the gain control signal VC will become smaller, so that the control unit 440 selects Amplifier unit 422 with a smaller gain value. That is, if the input signal Vi is at the minimum amplitude, the control unit 440 will first turn on the enabling switch SW1 and turn off the enabling switch SW2, so that the enabling amplifier circuit 520 is not the enabling amplifier circuit 540 . At this moment, the gain value of the amplifier module 420 is substantially equal to the gain value of the amplifier circuit 520 , and the gain value of the amplifier module 420 is the largest, and the linearity is the smallest. When the input signal Vi gradually increases, the control unit 440 turns on the enable switch SW1 and turns off the enable switch SW2 to disable the amplifier circuit 520 and enable the amplifier circuit 540 . Moreover, the control unit 440 turns on the main switch SW3 of the part according to the gain control signal VC to obtain the gain value of the amplifier circuit 540 corresponding to the input signal Vi. At this time, the gain value of the amplifier module 420 is the gain value of the amplifier circuit 540 , the gain value of the amplifier module 420 becomes smaller, and the linearity becomes larger. In this way, when the input signal Vi is the largest, the resistor module 543 is controlled to have the largest equivalent resistance value, so that the gain of the amplifier circuit 540 is the smallest and the linearity is the largest. In this way, the resistor module 543 can be designed according to the range of the amplitude of the input signal Vi, and in this range, there can be a corresponding gain value to amplify the input signal Vi without distortion, so as to achieve a high dynamic range adjustment gain value purpose of adjustment.

In addition, the DC bias isolation circuit 530 isolates the voltage between the transistors Q1 and Q2 and the bases of the transistors Q3 and Q4. In this way, when the selection unit switches the amplifier circuits 520 and 540, since the bases of the transistors Q1 and Q2 and the transistors Q3 and Q4 remain fixed respectively, the capacitors C1-C4 do not need to be charged or discharged, and the amplifier circuits 520 and 540 can Achieve fast switching and reduce the effect of instantaneous response time.

Further, the variable gain high dynamic range amplifier 500 may further include a resistor module 570 . The resistor module 570 includes a plurality of auxiliary resistors R3, R4 and a plurality of auxiliary switches SW4. The base of the transistor Q3 is further coupled to a plurality of auxiliary resistors R3, the base of the transistor Q4 is further coupled to a plurality of auxiliary resistors R4, each auxiliary resistor R3 is electrically connected to an auxiliary resistor R4 through an auxiliary switch SW4 . The control unit 440 also outputs a plurality of enable signals, such as AC1, AC2 and AC3, to control a plurality of auxiliary switches SW4, so that the resistor module 570 produces different equivalent resistance values. Since the gain value of the amplifier circuit 540 is not only affected by the resistance of the emitter terminal, but also affected by the resistance of the base terminal. Therefore, by using the resistor module 570, the switchable gain value of the amplifier circuit 540 can be increased, and the gain value of the amplifier circuit 540 can be adjusted more finely.

The amplifier circuits 520 and 540 of this embodiment share the output current adjustment circuit 460 to save circuit components and reduce costs. The output current regulating circuit 460 includes transistors Q5 - Q8 , and the collectors of the transistors Q6 and Q7 are electrically connected to a supply voltage Vcc. The emitters of the transistors Q5 and Q6 are both electrically connected to the collector of the transistor Q1 , and the emitters of the transistors Q7 and Q8 are both coupled to the collector of the transistor Q2 . The base of the transistor Q5 is electrically connected to the base of the transistor Q8 , the base of the transistor Q6 is electrically connected to the base of the transistor Q7 , and the voltages of the bases of the transistors Q5 and Q6 are controlled by the control unit 440 . The collectors of the transistor Q5 and the transistor Q8 are used to output the output signal Out.

The control unit 440 generates a current control signal Vcs according to the gain control signal VC to control the output current adjustment circuit 460 . By changing the voltage of the current control signal Vcs, the currents flowing through the transistors Q5 and Q8 can be changed to correspondingly change the magnitude of the output signal Out. The output signal Out can be a voltage output signal or a current output signal. In this embodiment, the output signal Out is taken as a voltage output signal for illustration. That is to say, when the amplifier circuit 520 or 540 outputs the current Io to the current regulating circuit 460, the voltage level of the current control signal Vcs will determine the ratio R of the output current Io flowing through the transistors Q5 and Q8, and a corresponding ratio R will be generated. The output signal Out. Therefore, the overall gain value of the amplifier module 420 is equivalent to the gain value of the amplifier circuit 520 or 540 multiplied by the ratio R whose value is less than 1.

Furthermore, the control unit 440 includes a pre-segmentation unit 580 and a unit converter 590 . The pre-segmentation unit 580 is used to receive the gain control signal VC, and correspondingly output a plurality of enable signals MC1-MC3, AC1-AC3, CSW1 and CSW2 according to the magnitude of the gain control signal VC, so as to turn on at least one main switch respectively. SW3 and at least one auxiliary switch SW4 are turned on to enable the switch SW1 or SW2. The pre-segmentation unit 580 is also used for generating a segment adjustment control signal VCseg according to the gain control signal VC. The output current adjustment circuit 460 adjusts the magnitude of the current signal Io according to the segment adjustment control signal VCseg. When the gain control signal VC increases or decreases linearly with time, the waveform of the segment adjustment control signal VCseg on the time axis is substantially a sawtooth wave. The unit converter 590 is used to adjust the magnitude of the segment adjustment control signal VCseg to generate the current control signal Vcs. The output current adjustment circuit 460 adjusts the magnitude of the current signal Io according to the adjusted segment adjustment control signal VCseg, that is, the current control signal Vcs.

Since the magnitude of the current flowing through the transistors Q5 - Q8 is related to the exponential value of the voltage across the base to the emitter. Therefore, preferably, the unit converter 590 converts the segment adjustment control signal VCseg whose voltage value changes linearly with time into the current control signal Vcs that can linearly change the magnitude of the current flowing through the transistors Q5 - Q8 .

Please refer to FIG. 6 , which shows an example of a circuit diagram of the pre-segmentation unit 580 in FIG. 5 . The pre-segmentation unit 580 includes an analog/digital converter 620 , a digital/analog converter 640 and a subtractor 660 . The analog/digital converter 620 is used to convert the gain control signal VC into a signal V1. The digital/analog converter 640 is used to convert the first signal V1 into a signal V2. The subtractor 660 is used for subtracting the second signal V2 from the gain control signal VC to generate the segment adjustment control signal VCseg.

Please refer to FIG. 6 , the pre-segmentation unit 580 may further include an amplifier unit selection circuit 680 for correspondingly outputting a plurality of enabling signals MC1-MC3, AC1-AC3, CSW1 and CSW2 according to the magnitude of the signal V1, to respectively Turn on at least one main switch SW3 and at least one auxiliary switch SW4, and turn on the enable switch SW1 or SW2.

Please also refer to FIGS. 7A-7D , which show an example of the waveform diagrams of the gain control signal VC and the segment adjustment control signal VCseg of the pre-segmentation unit 580 in FIG. 6 . Please refer to FIG. 7A and FIG. 7C , when the gain control signal VC increases or decreases linearly with time, the waveform of the segment adjustment control signal VCseg on the time axis is substantially a sawtooth wave, as shown in FIG. 7B and FIG. 7D . In FIG. 7C and FIG. 7D , the segment adjustment control signal VCseg is divided into five segments as an example for illustration. In the five sections, the section adjustment control signal VCseg respectively controls the five amplifier units 422 with different gain values. Take the five segments Seg1-Seg5 in FIG. 7D as an example for illustration. When the voltage value of the gain control signal VC decreases from the maximum value VC(max), the amplifier unit 422 corresponding to the segment Seg1 is selected, and the value of the segment adjustment control signal VCseg also decreases from VCseg(max), so that The ratio R of the current flowing through the transistors Q5 and Q8 of the output current adjusting circuit 460 to the output current Io starts to decrease from the maximum value. When the voltage value of the gain control signal VC drops to VC(1), the amplifier unit 422 corresponding to the segment Seg2 is selected, and the value of the segment adjustment control signal VCseg still decreases from VCseg(max), so that the output current The ratio R of the current flowing through the transistors Q5 and Q8 of the regulating circuit 460 to the output current Io still starts to decrease from the maximum value. The operation in the segments Seg3-Seg5 is also similar. The advantage of this method is that when switching between different amplifier units 422 with the magnitude of the gain control signal VC, the ratio R corresponding to the output current adjustment circuit 460 will first decrease from the maximum value, so that the The overall gain value of the variable gain high dynamic range amplifier 500 composed of the output current adjustment circuit 460 and the amplifier module 420 begins to decrease from the maximum gain value that can be achieved in this section. In this way, the variable range of the overall gain value of the variable gain high dynamic range amplifier 500 can be increased, and the overall benefit of the amplifier 500 can be improved.

In addition, in order to improve the resistance to noise and avoid excessive switching actions of the amplifier unit 422 caused by system instability, the section adjustment control signal corresponding to the waveform of the gain control signal VC in FIG. 7A and FIG. 7C The waveform of VCseg can also be designed as a tooth wave with hysteresis, which are shown in FIG. 8A and FIG. 8B respectively. Please refer to FIG. 7C and FIG. 8B at the same time. The so-called hysteresis here means that the ranges of two adjacent segments partially overlap. Assuming that the amplifier unit 422 corresponding to the current segment Seg1' is selected, when the voltage value of the gain control signal VC continues to drop to VC(1), the control unit 440 will not select a different amplifier unit 422 yet. The amplifier unit 422 corresponding to the segment Seg2' is not selected until the voltage value of the gain control signal VC continues to drop to VC'(1). The same is true for the reverse operation. Assume that the amplifier unit 422 corresponding to the current segment Seg2' is selected. When the voltage value of the gain control signal VC continues to rise to VC'(1), the control unit 440 will not select a different amplifier unit 422 yet. The amplifier unit 422 corresponding to the segment Seg1' is not selected until the voltage value of the gain control signal VC continues to rise to VC(1).

To sum up, although the present invention has been described above with an embodiment, it is not intended to limit the present invention. Those skilled in the art to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined by the content defined by the scope of the claims of the application.

Claims (11)

1. A variable gain high dynamic range amplifier comprising: An amplifier module, used to amplify an input signal, the amplifier module includes a plurality of amplifier units, the amplifier units are coupled in parallel, and the gain values of the amplifier units are different; a control unit for enabling at least one of the amplifier units according to a gain control signal, and the enabled at least one amplifier unit is used for outputting a current signal in response to the input signal; and An output current adjustment circuit, used to receive the current signal output from the enabled at least one amplifier unit, and under the control of the control unit, adjust the magnitude of the current signal to output an output signal correspondingly , each amplifier unit is coupled in series with the output current regulating circuit; Wherein, the control unit controls the output current adjustment circuit according to the gain control signal; Wherein, the gain control signal corresponds to the magnitude of the input signal, and the control unit includes: A pre-segmentation unit is used to receive the gain control signal, and correspondingly output a plurality of enable signals according to the magnitude of the gain control signal to respectively enable the amplifier units, the pre-segmentation unit is used to The gain control signal generates a segment adjustment control signal, and the output current adjustment circuit adjusts the magnitude of the current signal according to the segment adjustment control signal. When the gain control signal increases or decreases linearly with time, the segment adjustment The waveform of the control signal on the time axis is substantially a sawtooth wave. 2. The variable gain high dynamic range amplifier as claimed in claim 1, wherein the sawtooth wave is a sawtooth wave with hysteresis. 3. The variable gain high dynamic range amplifier of claim 1, wherein the pre-segmentation unit comprises: an analog/digital converter for converting the gain control signal into a first signal; a digital/analog converter for converting the first signal into a second signal; and A subtractor is used for subtracting the second signal from the gain control signal to generate the section adjustment control signal. 4. The variable gain high dynamic range amplifier as claimed in claim 1, wherein the control unit comprises a unit converter for adjusting the magnitude of the segment adjustment control signal, and the output current adjustment circuit adjusts the output current according to the adjusted The section adjusts the control signal to adjust the magnitude of the current signal. 5. The variable gain high dynamic range amplifier of claim 1, wherein the amplifier module comprises: a first amplifier circuit, including a first differential amplifier, for amplifying the input signal; A second amplifier circuit comprising: a current source unit; a second differential amplifier for amplifying the input signal, the second differential amplifier being coupled to the current source unit; and A first resistor module, coupled to the second differential amplifier, the first resistor module includes a plurality of main resistors and a plurality of main switches, each of which is selectively controlled by the control unit ground conduction, the main switch being turned on is used to make the corresponding main resistor have a current path, and the gain value of the second differential amplifier is related to the resistance value of the main resistor with the current path; and a selection unit, used to enable one of the first differential amplifier and the second differential amplifier under the control of the control circuit, so that the enabled first differential amplifier and the second differential amplifier One of the two amplifiers outputs the current signal corresponding to the input signal. 6. The variable gain high dynamic range amplifier as claimed in claim 5, wherein the first differential amplifier has a first transistor and a second transistor, the bases of the first transistor and the second transistor are used for receiving the input signal, the emitters of the first transistor and the second transistor are both coupled to ground voltage; Wherein, the current source unit includes a first current source and a second current source, the second differential amplifier includes a third transistor and a fourth transistor, and the main resistors include a plurality of first main resistors and A plurality of second main resistors, the bases of the third transistor and the fourth transistor are used to receive the input signal, the emitters of the third transistor and the fourth transistor are respectively coupled to the first current source and the first current source A second current source, the emitter of the third transistor is also coupled to the first main resistors, the emitter of the fourth transistor is also coupled to the second main resistors, each first main resistor electrically connected to a second main resistor through a main switch; Wherein, the collectors of the first transistor and the second transistor are respectively coupled to the collectors of the third transistor and the fourth transistor, and the collectors of the first transistor and the second transistor are used to output the current signal. 7. The variable gain high dynamic range amplifier as claimed in claim 6, wherein, comprising a signal input terminal, a DC bias isolation circuit and a bias circuit, the signal input terminal is used to receive the input signal, the DC The bias voltage isolation circuit is coupled between the signal input end and the amplifier module, and the bias voltage circuit is used for providing a DC bias voltage to the amplifier module. 8. The variable gain high dynamic range amplifier as claimed in claim 7, wherein the DC bias isolation circuit comprises four capacitors, one end of the four capacitors is coupled to the signal input end, and the other end of the four capacitors is One terminal is respectively coupled to the bases of the first transistor, the second transistor, the third transistor and the fourth transistor, and the bias circuit is used to provide a DC bias voltage to the first transistor, the second transistor, the The third transistor and the base of the fourth transistor. 9. The variable gain high dynamic range amplifier as claimed in claim 6, wherein the amplifier module comprises a second resistor module comprising a plurality of first auxiliary resistors, a plurality of second auxiliary resistors and a plurality of auxiliary switch, the base of the third transistor is also coupled to the first auxiliary resistors, the base of the fourth transistor is also coupled to the second auxiliary resistors, each of the first auxiliary resistors passes through an auxiliary The switch is electrically connected with one of the second auxiliary resistors. 10. The variable gain high dynamic range amplifier as claimed in claim 6, wherein the output current adjustment circuit comprises a fifth transistor, a sixth transistor, a seventh transistor and an eighth transistor, and the sixth transistor and the collector of the seventh transistor is electrically connected to a supply voltage, the emitters of the fifth transistor and the sixth transistor are electrically connected to the collector of the first transistor, the seventh transistor and the eighth transistor The emitters of both are coupled to the collector of the second transistor, the base of the fifth transistor is electrically connected to the base of the eighth transistor, and the base of the sixth transistor is electrically connected to the seventh transistor. base, the voltages of the bases of the fifth transistor and the sixth transistor are controlled by the control unit; Wherein, the collectors of the fifth transistor and the eighth transistor are used to output the output signal. 11. The variable gain high dynamic range amplifier as claimed in claim 5, comprising a matching unit, when the input signal is a single-ended input signal, the matching unit is used to convert the single-ended input signal The input signal of double-terminal input is generated, and the first differential amplifier and the second differential amplifier are used to amplify the input signal of double-terminal input.

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