RU2411639C1 - Complementary differential amplifier - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: complementary differential amplifier comprises the first (1) and second (2) input transistors (T), collectors of which are connected to collector of the first (3) auxiliary T, the first (4) and second (5) output T, bases of which are combined and connected to collector of the second (6) auxiliary T and the first (7) current-stabilising dipole (CD), emitter of the first T (1) is connected to emitter of the first T (4), emitter of the second T (2) is connected to emitter of the second T (5), current mirror (8), input of which is connected to collector of the first T (4), and output is connected to collector of the second T (5) and is connected to base of the third T (9), emitter of which is connected to the second CD (10) and is connected to output of device, besides, bases of the first T (3) and second T (6) are connected to each other. Circuit includes additional T (11), base of which is connected to collector of the first T (3), emitter is connected to bases of the first T (3) and second T (6), and collector is connected to input of current mirror (8).

EFFECT: reduced absolute value of U_cm and its temperature drift.

3 cl, 7 dwg

Description

The invention relates to the field of radio engineering and communication and can be used as a device for amplifying analog signals with a wide dynamic range in the structure of analog microcircuits for various functional purposes (for example, precision operational amplifiers (op amps)).

There are several basic differential cascade (DK) architectures. One of them (Fig. 1), which relates to classical architecture, was first used in the operational amplifier µA741.

There are known schemes of differential amplifiers (ДУ) on n-p-n and p-n-p transistors with the so-called "architecture of the input stage of the operational amplifier µA741" [1-7]. Over 50 patents have been issued for their modifications for leading microelectronic companies in the world. Differential amplifiers of this class, along with a typical parallel-balanced cascade, have become the main amplifying element of many analog interfaces. The present invention relates to this subclass of devices.

The closest in essence to the claimed technical solution is the classic scheme of remote control of figure 1, presented in the patent of Motorola USA No. 4.030.044, which is also present in a large number of other patents, for example [1-7].

A significant drawback of the known DE of FIG. 1 is that it has an increased value of the systematic component of the zero bias voltage (U _cm ), which depends on the properties of its architecture.

The main objective of the invention is to reduce the absolute value of U _cm and its temperature drift.

This object is achieved in that in the differential amplifier of figure 1, containing the first 1 and second 2 input transistors, the collectors of which are connected to the collector of the first 3 auxiliary transistors, the first 4 and second 5 output transistors, the bases of which are combined and connected to the collector of the second 6 auxiliary the transistor and the first 7 current-stabilizing bipolar, the emitter of the first 1 input transistor is connected to the emitter of the first 4 output transistor, the emitter of the second 2 input transistor is connected to the emitter the second 5 output transistor, a current mirror 8, the input of which is connected to the collector of the first 4 output transistor, and the output is connected to the collector of the second 5 output transistor and connected to the base of the third 9 auxiliary transistor, the emitter of which is connected to the second 10 current-stabilizing two-terminal device and connected to the output of the device moreover, the bases of the first 3 and second 6 auxiliary transistors are connected to each other, new elements and connections are provided - an additional transistor 11 is introduced into the circuit, the base of which is connected to the collector of the first 3 auxiliary transistors, the emitter is connected to the bases of the first 3 and second 6 auxiliary transistors, and the collector is connected to the input of the current mirror 8.

The amplifier circuit of the prototype is presented in figure 1. Figure 2 shows the inventive device in accordance with claim 1 of the claims.

Figure 3 presents the scheme of remote control corresponding to claim 1, claim 2 and claim 3 of the claims.

Figures 4 and 5 show the schemes of a differential amplifier - a prototype (Fig. 4) and the claimed remote control (Fig. 5) in a computer simulation environment PSpice on models of integrated transistors of FSUE NPP Pulsar. For a more efficient comparison of the known and the claimed devices, current mirrors in their collector circuits are made in the same way. In this case, it can be shown that the properties of the circuit of FIG. 4 in terms of U _cm are the same as those of FIG. 1.

In Fig.6 shows a diagram of the inventive device corresponding to claim 1, claim 2 and claim 3 of the claims, coinciding with figure 3.

Figure 7 shows the temperature dependence of the zero bias voltage of the circuits of figure 4, figure 5.

The differential amplifier of figure 2 contains the first 1 and second 2 input transistors, the collectors of which are connected to the collector of the first 3 auxiliary transistors, the first 4 and second 5 output transistors, the bases of which are combined and connected to the collector of the second 6 auxiliary transistor and the first 7 current-stabilizing two-terminal, emitter the first 1 input transistor is connected to the emitter of the first 4 output transistor, the emitter of the second 2 input transistor is connected to the emitter of the second 5 output transistor, current mirror Lo 8, the input of which is connected to the collector of the first 4 output transistor, and the output is connected to the collector of the second 5 output transistor and connected to the base of the third 9 auxiliary transistor, the emitter of which is connected to the second 10 current-stabilizing two-terminal device and connected to the output of the device, the bases of the first 3 and second 6 auxiliary transistors are connected to each other. An additional transistor 11 is introduced into the circuit, the base of which is connected to the collector of the first 3 auxiliary transistors, the emitter is connected to the bases of the first 3 and second 6 auxiliary transistors, and the collector is connected to the input of the current mirror 8.

In Fig.3 in accordance with claim 2 of the claims, a thermoradiation compensation transistor 14 is introduced into the circuit.

In Fig. 3, in accordance with claim 3, an auxiliary transistor 15 is introduced into the circuit, the emitter of which is connected to the emitter of the additional transistor 11, the base is connected to the base of the additional transistor 11, and the collector is connected to the bus of the power source 16.

Consider the factors that determine the systematic component of the bias voltage of zero U _cm in the circuit of figure 2, i.e. depending on the circuitry of the remote control.

If the currents of the two-terminal circuits 7 and 10 are equal to 2I ₀ , then the collector currents (I _k.i ) and base (I _b.i ) of the transistors of the circuit:

where I _b.i = I _e.i / β _i is the base current npn (I _b.p ) or pnp (I _b.n ) of the transistors of the circuit at their emitter current I _e.i = I ₀ ;

β _i is the current gain of the base of transistors.

Input I input ₈ and output I output ₈ currents of the current mirror 8

where K _i = 1 - modulus of the current transfer coefficient of the current mirror 12.

As a result, the current difference in node “A” when it is short-circuited to an equipotential common bus

where I _b . ₉ = 2I _{b. n} - base current pn-p of the transistor 9.

Substituting (1) ÷ (7) in (8), we find that the difference current determining U _cm ДУ is equal to zero: I _p = 0.

As a result, this reduces U _cm , since the differential current I _p in the node “A” creates U _cm , which depends on the steepness S of the conversion of the input differential voltage u _{in the} remote control into the output current of the node “A”:

where r _e1 = r _e2 = r _e4 = r _e5 are the resistance of the emitter junctions of transistors 1, 2, 4, 5.

Therefore, for the circuit of FIG. 2, the systematic component U _cm is close to zero:

where φ _Т = 26 mV is the temperature potential.

The introduction of a thermoradiation compensation transistor 14 (Fig. 3) improves the temperature stability of U _cm at t> 80 °.

The introduction of the transistor 15 allows you to provide the compensation effect U _cm when the emitter currents of the transistor 9, less than 2I ₀ .

In the remote control prototype I _p ≠ 0, therefore, the systematic component of U _{cm is} obtained three orders of magnitude more (U _cm = 2.0 mV) than in the claimed circuit (U _cm = -1 μV).

Computer simulation of the circuits of Figs. 4, 5, 6 confirms (Fig. 7) these theoretical conclusions.

Thus, the claimed device has significant advantages in comparison with the prototype in terms of the value of the static error of amplification of DC signals.

Bibliographic list

1. The patent of Germany №2.930.041.

2. RF patent No. 2019019.

3. RF patent No. 1107281.

4. A. St. USSR No. 375754.

5. US patent No. 4.030.044.

6. US patent No. 4.074.205.

7. US patent No. 4.286.227.

Claims (3)

1. A complementary differential amplifier containing the first (1) and second (2) input transistors, the collectors of which are connected to the collector of the first (3) auxiliary transistor, the first (4) and second (5) output transistors, the bases of which are combined and connected to the collector the second (6) auxiliary transistor and the first (7) current-stabilizing two-terminal device, the emitter of the first (1) input transistor is connected to the emitter of the first (4) output transistor, the emitter of the second (2) input transistor is connected to the emitter of the second (5) output o transistor, a current mirror (8), the input of which is connected to the collector of the first (4) output transistor, and the output is connected to the collector of the second (5) output transistor and connected to the base of the third (9) auxiliary transistor, the emitter of which is connected to the second (10) ) to a current-stabilizing two-terminal device and connected to the output of the device, the bases of the first (3) and second (6) auxiliary transistors connected to each other, characterized in that an additional transistor (11) is introduced into the circuit, the base of which is connected to the collector of the first (3) auxiliary mogatelnogo transistor, whose emitter is connected with the bases of the first (3) and second (6) auxiliary transistor and whose collector is connected to the input of the current mirror (8). 2. The device according to claim 1, characterized in that a thermo-radiation compensation transistor is introduced into the circuit (14). 3. The device according to claim 1, characterized in that the auxiliary transistor (15) is introduced into the circuit, the emitter of which is connected to the emitter of the additional transistor (11), the base is connected to the base of the additional transistor (11), and the collector is connected to the bus of the power source ( 16).

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