CN102651633B - Noise current feed-forward type noise cancellation circuit - Google Patents

Abstract

The invention discloses a noise current feed-forward noise cancellation circuit, which is composed of a resistive voltage parallel negative feedback amplifier circuit and a noise cancellation circuit, wherein the resistive voltage parallel negative feedback amplifier circuit consists of a transconductance input stage, a current A buffer stage and a resistive voltage parallel negative feedback network are composed; the noise canceling circuit is composed of a noise current signal detection stage, a noise current-voltage signal conversion stage, a noise voltage signal amplification stage and a mixed voltage signal synthesis stage, which are sequentially cascaded; The transconductance input stage, the input end of the noise current signal detection stage, the current buffer stage and the voltage parallel negative feedback network are connected in series in sequence; the output end of the current buffer stage is simultaneously connected with the three inputs of the mixed voltage signal synthesis stage Connected to one of the input terminals. Since the noise of the noise cancellation circuit itself can be suppressed by the transconductance input stage, the noise cancellation effect of the present invention is better than that of the traditional noise voltage feedforward noise cancellation circuit.

Description

A Noise Current Feedforward Noise Cancellation Circuit

technical field

The invention belongs to the technical field of analog integrated circuits, and in particular relates to a noise current feedforward noise cancellation circuit.

Background technique

Resistive voltage parallel negative feedback broadband low-noise amplifiers often use noise voltage feedforward noise cancellation circuits (see literature [1] and Figure 6) to reduce noise. This noise voltage feed-forward noise cancellation circuit is mainly composed of transconductance input stage, resistive voltage parallel negative feedback network, noise voltage signal detection stage and mixed voltage signal synthesis stage, and the transconductance input stage and resistive voltage parallel negative feedback The network is composed of a voltage parallel negative feedback amplifier, the input end of the noise voltage signal detection stage is connected in parallel with the input end of the transconductance input stage, the output end of the transconductance input stage and the output end of the noise voltage signal detection stage are respectively connected with the output end of the mixed voltage signal synthesis stage The two inputs are connected. The way to cancel the noise is to feed forward and amplify the noise voltage signal through the noise voltage signal detection stage, and then superimpose the noise signal of equal magnitude and opposite polarity and the information signal of equal magnitude and same polarity in the mixed voltage signal synthesis stage to cancel noise signal. It can be seen that the main disadvantages of this noise voltage feedforward noise cancellation circuit are: 1) Since the input terminal of the noise voltage signal detection stage is connected in parallel with the input terminal of the transconductance input stage, the noise of the noise voltage signal detection stage itself cannot It is suppressed by the transconductance input stage; 2) The noise voltage signal detection stage is required to have a large gain to offset the noise generated by the transconductance input stage and the feedback network, so the power consumption and area of this stage are relatively large; 3) due to The input terminal of the noise voltage signal detection stage and the input terminal of the transconductance input stage are connected in parallel. For the information signal, it is equivalent to the superposition of the signals amplified by two single-stage amplifiers in the mixed voltage signal synthesis stage, so the information signal The gain is relatively small.

In order to overcome the above-mentioned shortcomings of the traditional noise voltage feedforward noise cancellation circuit, the present invention proposes a noise current feedforward noise cancellation circuit, which includes a transconductance input stage, a resistive voltage parallel negative feedback network, and a mixed voltage signal synthesis stage. The three-stage circuit is the same as the traditional noise voltage feed-forward noise cancellation circuit, except that the noise current signal detection stage, noise current-voltage signal conversion stage and noise voltage signal amplification stage are introduced to replace the traditional noise voltage Noise voltage signal detection stage in feed-forward noise cancellation circuit. Among them, the noise current signal detection stage detects and feeds forward the noise current signal and information current signal generated (or amplified) by the transconductance input stage, and the noise current signal and information current signal are converted by the noise current-voltage signal conversion stage It is converted into a noise voltage signal and an information voltage signal, and then amplified by the noise voltage signal amplification stage to meet the conditions of noise voltage signal cancellation. In addition, a current buffer stage is introduced between the noise current signal detection stage and the mixed voltage signal synthesis stage to block the direct feedforward of the source signal through the transconductance input stage and the mixed voltage signal synthesis stage due to the Miller effect, And the noise current signal detection stage is isolated from the mixed voltage signal synthesis stage. At this time, since the input terminal of the noise current signal detection stage is connected in series with the output terminal of the transconductance input stage, the noise of the noise current signal detection stage and its subsequent stages can be suppressed by the transconductance input stage, so the additionally introduced The noise contribution of the four-stage circuit is relatively small.

A noise current feed-forward noise canceling circuit of the present invention has no related literature introduction, and no related patent documents have been searched.

Contents of the invention

The purpose and technical problem to be solved of the present invention is to propose a noise current feed-forward noise canceling circuit for the defects of the prior art.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A noise current feed-forward noise cancellation circuit is composed of two parts: a resistive voltage parallel negative feedback amplifier circuit and a noise cancellation circuit, wherein: the resistive voltage parallel negative feedback amplifier circuit consists of a transconductance input stage 1, a current buffer stage 2 and resistive voltage parallel negative feedback network 3; the noise cancellation circuit is composed of noise current signal detection stage 4, noise current-voltage signal conversion stage 5, noise voltage signal amplification stage 6 and mixed voltage signal synthesis stage 7 .

The above-mentioned transconductance input stage 1, current buffer stage 2, noise current signal detection stage 3, noise current-voltage signal conversion stage 5 and noise voltage signal amplification stage 6 are all four-port networks, namely two input ports and two output ports ports; the above-mentioned mixed voltage signal synthesis stage 7 is a five-port network, with three input ports and two output ports, and one of the input ports is the common end of the other two input ports.

The above-mentioned transconductance input stage 1, the input end of the noise current signal detection stage 4, the current buffer stage 2 and the resistive voltage parallel negative feedback network 3 are connected in series in sequence, that is, an output end of the transconductance input stage 1 is connected to the noise One input end of the current signal detection stage 4 is connected, the other input end of the noise current signal detection stage 4 is connected with an input end of the current buffer stage 2, and the other input end of the current buffer stage 2 is connected with the One output end of the current buffer stage 2 is connected, and the other output end of the current buffer stage 2 is connected with one end of the resistive voltage parallel negative feedback network 3; the other end of the resistive voltage parallel negative feedback network 3 At the same time, it is connected to one input terminal of the transconductance input stage 1 and a signal source, and the other input terminals and output terminals of the transconductance input stage 1 are grounded.

The output terminal of the above-mentioned noise current signal detection stage 4, the noise current-voltage signal conversion stage 5, the noise voltage signal amplification stage 6, the mixed voltage signal synthesis stage 7 and the load are cascaded in sequence, that is, the noise current signal detection stage 4 The output end is connected to the input end of the noise current-voltage signal conversion stage 5, the output end of the noise current-voltage signal conversion stage 5 is connected to the input end of the noise voltage signal amplification stage 6, and the noise voltage signal The output terminal of the amplification stage 6 is connected to the two input terminals of the mixed voltage signal synthesis stage 7, and one of them is a common terminal, and the third input terminal of the mixed voltage signal synthesis stage 7 is connected to the above-mentioned current buffer stage 2 The output terminal of the mixed voltage signal synthesis stage 7 is connected to the load.

The transconductance input stage 1 and the noise voltage signal amplification stage 6 mentioned above are all inverting amplifiers, which can be any one of single-stage common-source or single-stage common-emitter configurations.

The above-mentioned current buffer stage 2 may adopt any one of single-stage common gate or single-stage common base configurations.

The voltage parallel negative feedback network 3 mentioned above is realized by a single resistor.

The above-mentioned noise current signal detection stage 4 is realized by using a current sensor or a transformer.

The noise current-voltage signal conversion stage 5 mentioned above is realized by a passive or active current-voltage conversion circuit.

If the current direction of the loop formed by the output terminal of the above-mentioned noise current signal detection stage 4 is the same as the current direction of the loop formed by the input terminal, then the output signal of the above-mentioned mixed voltage signal synthesis stage 7 is the sum of its two input signals, and adopt It is realized by an adding circuit made up of active devices. In the present invention, this type of noise current feedforward type noise cancellation circuit is called noise current feedforward "sum" type noise cancellation circuit; if the above-mentioned noise current signal detection stage 4 The current direction of the loop formed by the output end is opposite to the current direction of the loop formed by the input end, then the output signal of the above-mentioned mixed voltage signal synthesis stage 7 is the difference between its two input signals, and it is realized by a subtraction circuit composed of active devices. This type of noise current feedforward type noise canceling circuit is referred to as a noise current feedforward "difference" type noise canceling circuit in the present invention.

A noise current feed-forward noise cancellation circuit of the present invention has the following advantages and beneficial effects:

1. Since the noise cancellation circuit in a noise current feed-forward noise cancellation circuit of the present invention detects and feeds forward the current signal, the input terminal of the noise current signal detection stage is connected in series with the output terminal of the transconductance input stage , so the noise generated by the noise canceling circuit can be suppressed by the transconductance input stage;

2, because the noise current signal in a kind of noise current feed-forward type noise cancellation circuit of the present invention is first detected by the noise current signal detection stage, then converted into a voltage by the noise current-voltage signal conversion stage, these two stages of circuits are sensitive to the noise signal It has an amplification effect, so that the gain of the noise voltage signal amplification stage can be reduced, thereby reducing the power consumption and chip area of the noise voltage signal amplification stage;

3. For information signals, since the transconductance input stage, noise current signal detection stage, noise current-voltage signal conversion stage and noise voltage signal amplification stage in a noise current feed-forward noise cancellation circuit of the present invention are stages It is equivalent to a two-stage cascaded amplifier, so the gain of the information signal is relatively large.

Description of drawings

Fig. 1 is a schematic diagram of the principle of the present invention;

Fig. 2 is a specific implementation circuit diagram of a noise current feed-forward "sum" type noise canceling circuit shown in Fig. 1;

Fig. 3 is a specific implementation circuit diagram of a noise current feed-forward "difference" type noise canceling circuit shown in Fig. 1;

Fig. 4 is a schematic diagram of the signal of each key node voltage or loop current in Fig. 2 and a schematic diagram of the noise cancellation process;

Fig. 5 is a schematic diagram of the signal of each key node voltage or loop current in Fig. 3 and a schematic diagram of the noise cancellation process;

FIG. 6 is a specific implementation circuit diagram of a traditional noise voltage feedforward noise cancellation circuit.

Fig. 7 is the noise figure (NF) of Fig. 2 and Fig. 6 based on the embodiment of 0.2 μm GaAs p-HEMT process simulation;

Fig. 8 is an embodiment based on 0.2μm GaAs p-HEMT process simulation Fig. 2 and Fig. 6 input reflection coefficient (S11) and power gain (S21);

In the figure: 1. Transconductance input stage, 2. Current buffer stage, 3. Voltage parallel negative feedback network, 4. Noise current signal detection stage, 5. Noise current-voltage signal conversion stage, 6. Noise voltage signal amplification stage, 7. Mixed voltage signal synthesis stage.

Detailed ways

In order to deepen the understanding of the present invention, the present invention will be further described below in conjunction with the examples and accompanying drawings. The examples are only used to explain the present invention, and do not constitute the regulation to the protection scope of the present invention.

FIG. 2 and FIG. 3 are circuit diagrams of the specific implementations of the two field-effect transistor-based processes in FIG. 1 . A noise current feed-forward noise cancellation circuit shown in Figure 1, Figure 2 and Figure 3 is composed of a resistive voltage parallel negative feedback amplifier circuit and a noise cancellation circuit. Wherein, the resistive voltage parallel negative feedback amplifying circuit is composed of a transconductance input stage 1, a current buffer stage 2 and a resistive voltage parallel negative feedback network 3; the noise canceling circuit is composed of a noise current signal detection stage 4, a noise It consists of a current-voltage signal conversion stage 5, a noise voltage signal amplification stage 6 and a mixed voltage signal synthesis stage 7.

Fig. 2 is a specific implementation circuit diagram of a noise current feed-forward "sum" type noise canceling circuit shown in Fig. 1 . In Fig. 2, the transconductance input stage is realized by a single-stage common-source amplifier VF101, the current buffer stage 2 is realized by a single-stage common-gate amplifier VF201, and the voltage parallel negative feedback network is realized by a feedback resistor R _f is realized, and the described noise current signal detection stage 4 is realized by the integrated transformer TF401 with a turns ratio of 1:1, and the described noise current-voltage conversion stage 5 is formed by a resistor R501, and the described noise voltage signal amplification stage 6 is realized by a single-stage common-source amplifier VF601, and the mixed voltage signal synthesis stage 7 is realized by a single-stage common-drain amplifier VF701. In Fig. 2, the resistive voltage parallel negative feedback amplifying circuit is composed of VF101, the primary coil of TF401, VF201 and _Rf and connected in series in sequence, that is, the source signal is coupled to the gate of VF101 through the coupling capacitor C1, and drains from VF101 The current signal output by the pole is input to the source of VF201 through the primary coil of TF101, the drain of VF201 is connected to one end of R _f and the gate of VF701, the other end of R _f is connected to the gate of VF101, and the source of VF101 is grounded , the gate of VF201 is connected to the power supply U _G2 . The noise canceling circuit is composed of the secondary coil of TF401, R501, VF601 and VF701 and is cascaded in sequence, that is, the terminal with the same name of the secondary coil of TF401 is connected to one end of R501 and the gate of VF601 at the same time, and the other end of R501 is connected to the gate of VF601. The sources are all grounded, the drain of VF601 is connected to the source of VF701, and the output voltage signal is output to the load through the coupling capacitor C2, the drain of VF701 is connected to the power supply VDD, and the opposite end of the secondary coil of TF401 is connected to the power supply U _G3 . VFB1, VFB2, VFB3 and resistor RB1 form a mirror current source to provide bias current for VF101, VF201 and VF601, that is, the sources of VFB1, VFB2 and VFB3 are all connected to the power supply VDD, the gate of VFB1 and the drain of VFB1, VFB2 The gate of VFB3, the gate of VFB3 and one end of resistor RB1 are connected, the other end of RB1 is grounded, and the drain of VFB3 is connected with the drain of VF601. Among the above transistors, VF101, VF201, VF601 and VF701 are N-channel field effect transistors, and VFB1, VFB2 and VFB3 are P-channel field effect transistors. The dimensions of VF101 and VF201 are the same, and the dimensions of VFB1 and VFB2 are the same.

Fig. 3 is a specific implementation circuit diagram of a noise current feed-forward "difference" type noise canceling circuit shown in Fig. 1 . The transconductance input stage 1, current buffer stage 2, resistive voltage parallel negative feedback network 3 and noise current-voltage signal conversion stage 5 in Fig. 3 are the same as Fig. 2, but its noise current signal detection stage 4 and mixed voltage signal synthesis Level 7 is different from Figure 2. Specifically, the noise current signal detection stage 4 described in Figure 3 is still realized by an integrated transformer TF401 with a turns ratio of 1:1, but the connection mode of its secondary coil is opposite to that of Figure 2, that is, the synonym of the secondary coil of TF401 Terminal connects one end of R501 and the gate of VF601 at the same time, and its terminal of the same name is connected to power supply U _G3 ; Described mixed voltage signal synthesis stage 7 is composed of common drain amplifiers VF701 and VF702 and the turns ratio is And the primary coil has an integrated transformer TF701 with an intermediate tap. The gate of VF701 is connected to the drain of VF201 and the gate of VF702 is connected to the drain of VF601. The sources of VF701 and VF702 are respectively connected to the two ends of the primary coil of TF701; the middle tap of the primary coil of TF701 is grounded, and the two ends of the secondary coil of TF701 The terminals are respectively connected to the two ends of the load, and the drains of VF701 and VF702 are connected to the power supply VDD. The other parts of the circuit and their connections in Figure 3 are the same as those in Figure 2.

Based on the 0.2μm GaAs p-HEMT process, in the working frequency band of 0.5-2GHz, the performance of the circuit shown in Figure 2 and Figure 6 of this embodiment was simulated with ADS software, and the results are shown in Figure 7 and Figure 8. It can be seen that the noise figure (NF) in Fig. 2 of this embodiment is 0.67-0.71dB, the input reflection coefficient (S11) is less than -14dB, and the power gain (S21) is 23-28dB. However, with a similar circuit structure and the same bias current, the noise figure NF of the traditional noise voltage feedforward noise cancellation circuit (Figure 6) is 0.71~0.73dB, the input reflection coefficient S11 is less than -11dB, and its power gain is S21 18 ~ 20dB. It can be seen that with the same power consumption, the noise cancellation effect of the noise current feedforward noise cancellation circuit of the present invention is better than that of the traditional noise voltage feedforward noise cancellation circuit.

Claims (4)

1. A noise current feedforward type noise canceling circuit is composed of a resistive voltage parallel negative feedback amplifier circuit and a noise canceling circuit, and is characterized in that: the resistive voltage parallel negative feedback amplifier circuit consists of a transconductance input stage (1 ), a current buffer stage (2) and a resistive voltage parallel negative feedback network (3); the noise cancellation circuit is composed of a noise current signal detection stage (4), a noise current-voltage signal conversion stage (5), a noise voltage It consists of a signal amplification stage (6) and a mixed voltage signal synthesis stage (7); the transconductance input stage (1), current buffer stage (2), noise current signal detection stage (4), noise current-voltage signal The conversion stage (5) and the noise voltage signal amplification stage (6) are four-port networks, that is, two input ports and two output ports; the mixed voltage signal synthesis stage (7) is a five-port network, that is, three An input port and two output ports, and one of the input ports is the common end of the other two input ports; the transconductance input stage (1), the input end of the noise current signal detection stage (4), and the current buffer stage (2) connected in series with the resistive voltage parallel negative feedback network (3), that is, one output terminal of the transconductance input stage (1) is connected with one input terminal of the noise current signal detection stage (4), and the The other input end of the noise current signal detection stage (4) is connected to one input end of the current buffer stage (2), and the other input end of the current buffer stage (2) is connected to the current buffer stage (2) One output end of the current buffer stage (2) is connected to one end of the resistive voltage parallel negative feedback network (3); the other end of the resistive voltage parallel negative feedback network (3) One end is connected to an input terminal of the transconductance input stage (1) and a signal source at the same time, and the other input terminals and output terminals of the transconductance input stage (1) are grounded; the noise current signal detection stage (4 ), the noise current-voltage signal conversion stage (5), the noise voltage signal amplification stage (6), the mixed voltage signal synthesis stage (7) and the load are sequentially cascaded, that is, the noise current signal detection stage (4) The output end of the noise current-voltage signal conversion stage (5) is connected to the input end of the noise current-voltage signal conversion stage (5) and the input end of the noise voltage signal amplification stage (6) The output terminal of the noise voltage signal amplification stage (6) is connected to the two input terminals of the mixed voltage signal synthesis stage (7), and one of them is a common terminal, and the mixed voltage signal synthesis stage (7) The third input terminal of the circuit breaker is connected to the output terminal of the current buffer stage (2), and the output terminal of the mixed voltage signal synthesis stage (7) is connected to a load. 2. The noise current feed-forward noise canceling circuit according to claim 1, characterized in that: the resistive voltage parallel negative feedback network (3) is realized by a single resistor. 3. The noise current feed-forward noise cancellation circuit according to claim 1, characterized in that: the noise current signal detection stage (4) is realized by a current sensor or a transformer. 4. The noise current feed-forward noise cancellation circuit according to claim 1, characterized in that: the transconductance input stage (1) and the noise voltage signal amplification stage (6) are both inverting amplifiers.