RU2446554C1 - Differential operational amplifier with paraphase output - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: differential operational amplifier with paraphase output comprises an input differential cascade, the first and second current mirrors, the first current-stabilising dipole, the first and second current-stabilising load dipoles, an additional transistor, the first and second feedback resistors, the first and second additional buffer amplifiers.

EFFECT: development of conditions, under which the output static cophased voltage of the DA will have high stability and value close to zero.

9 dwg

Description

The invention relates to the field of radio engineering and communication and can be used as a device for amplifying analog signals in the structure of analog microcircuits for various functional purposes (for example, bridge power amplifiers, filters, comparators, etc.).

Known schemes of classical two-stage differential operational amplifiers (DU) based on current mirrors with a paraphase output, which became the basis of many serial analog circuits [1-11]. Remote controls of this class are also actively used in the structure of microwave devices implemented on the basis of SiGe technologies. This is due to the possibility of building on their basis active RC filters of the GHz range for modern and promising telecommunication systems, drivers of differential communication lines between SF blocks A / d or a / D classes, and so on.

The closest prototype (figure 1) of the claimed device is a differential amplifier according to patent application US 2006/0006910, comprising an input differential stage 1 with a first 2 and a second 3 current outputs and a low-impedance output 4 of the common emitter circuit connected to the bus of the first 5 power supply through the first 6 a current-stabilizing two-terminal device, the first 7 current mirror, the input of which is connected to the first 2 current output of the input differential stage 1, and the output is connected to the first 8 auxiliary output of the device and through the first 9 tocosts a stabilizing load double-pole is connected to the bus of the first 5 power supply, a second 10 current mirror, the input of which is connected to the second 3 current output of the input differential stage 1, and the output is connected to the second 11 auxiliary output of the device and through the second 12 current-stabilizing load double-pole is connected to the bus of the first 5 power supply, and the bus of the second 13 power source is connected to the common emitter outputs of the first 7 and second 10 current mirrors.

A significant drawback of the known DE of FIG. 1 is that with a low-impedance load (for example, R _n = 4 Ohms) connected to the outputs 8 and 12, as well as the implementation of the rail-to-rail option, it has an unstable output common-mode voltage level, depending on R _n and the parameters of the current-stabilizing dvukhpolosnykh 9, 12, 6. This greatly complicates its coordination with subsequent functional units, does not allow to implement on its basis bridge power amplifiers of the high and microwave range.

The main objective of the invention is to create conditions under which the output static common-mode voltage of the remote control will have high stability and close to zero value at low resistance loads (1 ÷ 4 Ohms). In this case, a wider range of variation of the output signal of the remote control is also realized.

The problem is solved in that in a differential operational amplifier with a paraphase output of Fig. 1, containing an input differential stage (1) with a first (2) and a second (3) current outputs and a low-impedance output (4) of the common emitter circuit connected to the bus of the first (5) the power source through the first (6) current-stabilizing two-terminal device, the first (7) current mirror, the input of which is connected to the first (2) current output of the input differential stage (1), and the output is connected to the first (8) auxiliary output of the device and through first (9) tokos an abilizing load two-terminal device is connected to the bus of the first (5) power source, the second (10) current mirror, the input of which is connected to the second (3) current output of the input differential stage (1), and the output is connected to the second (11) auxiliary output of the device and through the second (12) current-stabilizing two-pole load is connected to the bus of the first (5) power source, and the bus of the second (13) power source is connected to the common emitter outputs of the first (7) and second (10) current mirrors, new elements and connections are provided in the circuit in there is an additional transistor (14), the emitter of which is connected to the low-impedance output (4) of the common emitter circuit of the input differential stage (1), and the collector is connected to the bus of the second (13) power source, and the first (8) auxiliary output of the device is connected to the base of the additional transistor (14) through the first (19) additional buffer amplifier and the first (15) feedback resistor connected in series, and the second (11) auxiliary output of the device is connected to the base of the additional transistor (14) through the series connected e second (20) an additional buffer amplifier and a second (16) feedback resistor.

The drawing of figure 1 shows a diagram of the remote control prototype.

The drawing of figure 2 shows a diagram of the inventive device in accordance with the claims.

The drawing of figure 3 shows a diagram of the inventive remote control with the architecture of figure 3, in which additional buffer amplifiers 19 and 20 are made in the particular case based on a transistor 21 and a two-terminal 22, as well as a transistor 23 and a two-terminal 24.

In the drawing of Fig. 4, a diagram of the claimed remote control of Fig. 3 is shown in a Cadance computer simulation environment on SiGe models of integrated transistors, and in the drawing of Fig. 5 is a dependence of its voltage gain on frequency.

The drawing of Fig.6 shows the dependence of the output voltages for the paraphase and differential outputs of the remote control of Fig.4 from the input sinusoidal voltage with an amplitude u _in = 1 mV. The graphs of Fig.6 show that the claimed remote control has two out-of-phase output voltages and a zero level of output common-mode static voltage.

The drawing of Fig.7 shows a diagram of the inclusion of the proposed remote control in the structure of the driver of the differential communication line.

The drawing of Fig. 8 shows a specific driver diagram of Fig. 7 based on the remote control of Fig. 4 in a Cadence environment on models of integrated SiGe transistors, and Fig. 9 shows the frequency dependence of its differential gain.

The differential operational amplifier with a paraphase output of Fig. 2 contains an input differential stage 1 with a first 2 and a second 3 current outputs and a low-impedance output 4 of the common emitter circuit connected to the bus of the first 5 power supply through the first 6 current-stabilizing two-terminal device, the first 7 current mirror, the input of which connected to the first 2 current output of the input differential stage 1, and the output is connected to the first 8 auxiliary output of the device and through the first 9 current-stabilizing bipolar load connected to the bus the first 5 power supply, the second 10 current mirror, the input of which is connected to the second 3 current output of the input differential stage 1, and the output is connected to the second 11 auxiliary output of the device and through the second 12 current-stabilizing two-terminal load connected to the bus of the first 5 power supply, and the bus of the second 13 of the power source is connected to the common emitter outputs of the first 7 and second 10 current mirrors. An additional transistor (14) is introduced into the circuit, the emitter of which is connected to the low-impedance output (4) of the common emitter circuit of the input differential stage (1), and the collector is connected to the bus of the second (13) power source, and the first (8) auxiliary output of the device is connected to the base of the auxiliary transistor (14) through the first (19) additional buffer amplifier and the first (15) feedback resistor connected in series, and the second (11) auxiliary output of the device is connected to the base of the additional transistor (14) through the series connected to the second (20) an additional buffer amplifier and a second (16) feedback resistor.

The drawing of figure 3 shows a diagram of the inventive remote control with the architecture of figure 2, in which additional buffer amplifiers 19 and 20 are made in the particular case based on a transistor 21 and a two-terminal 22, as well as a transistor 23 and a two-terminal 24.

As the first 6 current-stabilizing bipolar, the authors recommend using classical sources of reference current on transistors or relatively high-resistance resistors.

The first 9 and second 12 current-stabilizing bipolar loads are implemented as reference current sources on transistors.

Current mirrors 7 and 10 are performed according to classical schemes.

Consider the operation of the remote control of figure 2.

The static current mode of the transistors 14, 17 and 18 of the proposed remote control is set by bipolar 6, 9 and 12. Moreover, the collector and emitter currents of the transistors 17, 18 and 14 are determined by the formulas:

where I ₀ is the set value of the static current, for example 1 mA.

The static voltage U * ₈ at the output of Output. * 1 and U * ₁₁ at the Output. * 2 of the remote control at a zero input signal (u _in = 0) can be found from the equation:

where U _eb . ₁₇ = U _eb . ₁₈ = U _{eb. 14} - voltage "emitter-base" of the input transistors 17 and 18 and the additional transistor 14 at the emitter current I _ei = I ₀ ;

I _b - the current component of the base of the transistor 14 in the feedback resistor 15 (16).

Thus, firstly, with low-impedance loads R _n connected to the outputs O * * .1 and O * * 2 (R _n = 1 ÷ 4 Ohms), and typical values of the base current of the transistor 14, as well as with R ₁₅ = R ₁₆ = 50 ÷ 100 Ohm the common mode output voltage of the remote control of FIG. 2 is practically zero in a wide range of temperature and radiation effects, as well as changes in supply voltages.

Secondly, the considered remote control provides the maximum possible (with low-impedance loads R _n = 1 ÷ 4 Ohms connected to the outputs O * * .1 and O * * .2) out-of-phase voltages at the outputs close to the corresponding supply voltages E ₁₃ and E ₅ . In this case, the numerical values of R _n in the claimed scheme have a rather weak effect on the zero level of the output common mode signal of the remote control. This effect in the remote control prototype is not implemented.

With a common-mode voltage variation at the inputs Vx.1 and Bx.2, the common-mode voltages at the outputs Output * .1 and Output. * 2 also change. However, the emitter (collector) current of the transistor 14 remains constant:

Therefore, the attenuation coefficient of the input common-mode voltage in the claimed remote control is quite high, since the current mode of the transistors 17 and 18 does not change.

независимо от статических параметров этих дополнительных буферных усилителей 19 и 20 и сопротивлений низкоомной нагрузки. В схеме фиг.2 в низкоомной нагрузке R_н, включенной между выходами Вых.*1 и Вых.*2, могут быть получены значительно большие мощности, которые определяются свойствами дополнительных буферных усилителей 19 и 20. Кроме этого, в архитектуре рис.2 максимальные амплитуды выходных напряжений положительной

отрицательной

полярностей близки к сумме напряжений первого 5 (Е₅) и второго 13 (Е₁₃) источников питания

, что является одной из ее замечательных особенностей.Thus, the presence of additional buffer amplifiers 19 and 20 significantly reduces the requirements for the resistance values of the feedback resistors 15 and 16, which makes it possible to obtain zero levels of static voltages at the outputs. * 1 and Output. * 2

regardless of the static parameters of these additional buffer amplifiers 19 and 20 and low impedance load resistances. In the circuit of Fig. 2, at a low-impedance load R _n connected between the outputs O *. 1 and O. * 2, significantly higher powers can be obtained, which are determined by the properties of additional buffer amplifiers 19 and 20. In addition, in the architecture of Fig. 2, the maximum the amplitude of the output voltage is positive

negative

polarities are close to the sum of the voltages of the first 5 (E ₅ ) and second 13 (E ₁₃ ) power sources

That is one of its wonderful features.

Thus, the proposed remote control has significant advantages in comparison with the prototype.

Information sources:

1. US Patent Application No. 2005/0218983

2. US Patent Application No. 2006/0139098

3. US Patent Application No. 2006/0006910 fig. one

4. US Patent No. 6,657.465

5. US Patent No. 6,831,513 fig. four

6. US Patent No. 6,844.781

7. US Patent Application No. 2008/0032656 fig.6

8. US Patent No. 6,657.465

9. US Patent No. 6,538.513

10. US patent application No. 2003/0132803 fig.4

11. US Patent No. 6,882,185 fig. four

Claims (1)

A differential operational amplifier with a paraphase output, comprising an input differential stage (1) with the first (2) and second (3) current outputs and a low-impedance output (4) of the common emitter circuit connected to the bus of the first (5) power source through the first (6) current-stabilizing two-terminal device, the first (7) current mirror, the input of which is connected to the first (2) current output of the input differential stage (1), and the output is connected to the first (8) auxiliary output of the device and through the first (9) current-stabilizing two-terminal load connection connected to the bus of the first (5) power source, the second (10) current mirror, the input of which is connected to the second (3) current output of the input differential stage (1), and the output is connected to the second (11) auxiliary output of the device and through the second (12) ) a current-stabilizing bipolar load is connected to the bus of the first (5) power source, and the bus of the second (13) power source is connected to the common emitter outputs of the first (7) and second (10) current mirrors, characterized in that an additional transistor (14 ), the emitter of which is connected to low-resistance output (4) of the common emitter circuit of the input differential stage (1), and the collector is connected to the bus of the second (13) power source, and the first (8) auxiliary output of the device is connected to the base of the additional transistor (14) through the first (19) connected in series additional buffer amplifier and the first (15) feedback resistor, and the second (11) auxiliary output of the device is connected to the base of the additional transistor (14) through the second buffer amplifier (20) and the second (16) feedback hist.

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