RU2394364C1 - Two-channel controlled alternating current amplifier - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: two-channel controlled alternating current amplifier (dwg.4) includes source of input (1) and control (2) signals, first (3) and second (4) control transistors (T), first (5) and second (6) output T the bases of which are combined; collector of T (5) is connected to first (7) load circuit and to output (8) of the first amplification channel; collector of T (6) is connected to second (9) load circuit and to output (10) of the second amplification channel; emitter of T (5) is connected to first (11) current-stabilising bipole (CB); emitter of T (6) is connected to second (12) CB. Source of input signal (1) is connected to combined bases of T (5) and T (6); control signal source (2) is connected between bases of T (3) and T (4); emitters of T (3) and T (4) are connected to emitter of T (5) and to emitter of T (6) respectively through first (13) and second (14) separating capacitors (C); at that, emitters of T (3) and T (4) are connected to the appropriate outputs (15) and (16) of additional circuit (17) of static mode T (3) and T (4).

EFFECT: maintaining the constant product of transfer factors via both amplification channels.

2 cl, 8 dwg

Description

The invention relates to the field of radio engineering and communication and can be used as an alternating current amplifier, the voltage transfer coefficients of which (K _y1 , K _y2 ) depend on the level of the control signal (U _y ). Such devices are used in the structure of analog microcircuits for various functional purposes, automatic gain control systems, analog signal multipliers, active filters, etc.

In electronic equipment, two-channel controlled amplifiers (ДУУ) with one input and two outputs are used, with respect to which the transmission coefficients for voltage (К _у1 , К _у2 ) change out of phase - if К _у1 increases in proportion to U _у (Out.1) and inversely to ( Out.2) the control signal U _y . For example, for electronic control of the frequency of the quasi-resonance ω _{p of} active RC filters, it is necessary to have controlled amplifiers with the widest possible range of variation of the ratios K _у1 / К _у2 [1,2], because ratio K _y1 / K _y2 , which determines the possible range of frequency adjustment of the electoral system

,

,

where ω ₀ is the tuning frequency of the RC filter at K _y1 = K _y2 .

For most applications, it is also necessary to have K _y1 K _y2 ≈const [1], which ensures constant filter attenuation over the entire frequency tuning range.

The proposed device can be used to solve problems of this class, as well as in other cases requiring antiphase control of the amplification factors K _u1 and K _y2 .

In electronic equipment, DUUs based on Gilbert cells are widely used [3-15]. The closest in technical essence to the claimed device includes a controlled AC amplifier described in US patent No. 4.331.929. It contains (Fig. 1) a source of input 1 and control 2 signals, the first 3 and second 4 control transistors, the first 5 and second 6 output transistors, the bases of which are combined, the collector of the first 5 output transistor is connected to the first 7 load circuit and the output 8 of the first amplification channel, the collector of the second 6 output transistor is connected to the second 9 load circuit and the output 10 of the second amplification channel, the emitter of the first 5 output transistor is connected to the first 11 current-stabilizing two-terminal, the emitter of the second 6 output transistor is connected to the second 12 current-stabilizing bipolar.

и

изменяются синфазно.A significant drawback of the known two-channel controlled amplifier (DUU) is that the law of change of the transfer coefficient K _у1 from the input u _x to the output of the first 8 gain channel coincides with the law of the change of the transfer coefficient K _у2 from the input u _x to the output 10 of the second amplification channel, t .e.

and

change in phase.

The main objective of the invention is to create conditions under which the transmission coefficient from the input u _x to the output 8 K _{y1 of the} first amplification channel increases proportionally to the control signal U _y , and the transmission coefficient from the input u _x to the output 10 K _{y2 of the} second amplification channel decreases proportionally to the signal control u _y In this case, K _{y1 y2} · K ≈const.

This goal is achieved in that in a controlled AC amplifier (Fig. 1), containing a source of input 1 and control 2 signals, the first 3 and second 4 control transistors, the first 5 and second 6 output transistors, the bases of which are combined, the collector of the first 5 output the transistor is connected to the first 7 load circuit and the output 8 of the first amplification channel, the collector of the second 6 output transistor is connected to the second 9 load circuit and the output 10 of the second amplification channel, the emitter of the first 5 output transistor is connected to the first 11 tocosts by using an alternating two-terminal, the emitter of the second 6 output transistor is connected to the second 12 current-stabilizing two-terminal, new elements and connections are provided - the input signal source 1 is connected to the combined bases of the first 5 and second 6 output transistors, the control signal source 2 is connected between the bases of the first 3 and second 4 control transistors, the emitter of the first 3 control transistors is connected to the emitter of the first 5 output transistor through the first 13 isolation capacitor, the emitter of the second 4 control trans the source is connected to the emitter of the second 6 output transistor through the second 14 isolation capacitor, and the emitters of the first 3 and second 4 control transistors are connected to the corresponding first 15 and second 16 outputs of the additional circuit 17 for establishing the static mode of the first 3 and second 4 control transistors.

Figure 1 shows the circuit of a notch filter based on a TT bridge, in which a two-channel controlled AC amplifier is used to tune the quasi-resonance frequency, in which the transmission coefficient K _y1 changes in direct proportion to the control signal, and K _y2 is out of phase with K _y2 .

Figure 2 shows the dependence of the amplitude-frequency characteristics of the filter of figure 1 at different ratios K _y1 / K _y2 .

Figure 3 shows a diagram of a two-channel controlled amplifier (DUU) - prototype.

Figure 4 shows a diagram of the claimed DUU in accordance with claim 1 and claim 2 of the claims.

The scheme of figure 5 corresponds to the scheme of figure 4. However, here, to explain the work, the directions of constant and variable currents are shown.

In Fig.6 shows a diagram of the remote control of Fig.4 in the computer simulation environment PSpice on the models of integrated transistors FSUE NPP Pulsar. The results of its modeling are shown in Fig.7 - Fig.8:

- the dependence of the gain K _y on the frequency at different control voltages U _y (Fig.7);

- the dependence of the gain on the voltage K _y from the control voltage U _y in the range of medium frequencies (Fig. 8).

The two-channel controlled AC amplifier of figure 2 contains a source of input 1 and control 2 signals, the first 3 and second 4 control transistors, the first 5 and second 6 output transistors, the bases of which are combined, the collector of the first 5 output transistor is connected to the first 7 load circuit and the output 8 of the first amplification channel, the collector of the second 6 output transistor is connected to the second 9 load circuit and the output 10 of the second amplification channel, the emitter of the first 5 output transistor is connected to the first 11 current-stabilizing two-terminal, 6 Mitter second output transistor 12 is connected to a second two-pole tokostabiliziruyuschim. The input signal source 1 is connected to the combined bases of the first 5 and second 6 output transistors, the control signal source 2 is connected between the bases of the first 3 and second 4 control transistors, the emitter of the first 3 control transistor is connected to the emitter of the first 5 output transistor through the first 13 isolation capacitor, emitter the second 4 control transistor is connected to the emitter of the second 6 output transistor through the second 14 isolation capacitor, and the emitters of the first 3 and second 4 control transistors They are connected with the corresponding first 15 and second 16 outputs of the additional circuit 17 for establishing the static mode of the first 3 and second 4 control transistors.

In the circuit of Fig. 4, in accordance with claim 2, the circuit for establishing a static mode 17 contains an auxiliary resistor 18 connected between its first 15 and second 16 outputs, as well as the first 19 and second 20 additional current-stabilizing two-pole connected to its corresponding first 15 and second 16 exits.

Consider the operation of the circuit of Fig.5.

At zero control voltage U _y = 0, the current through the resistor 18 (I _y ) is equal to zero. Therefore, the emitter currents and, therefore, the differential resistance of the emitter transitions of transistors 3 and 4 (r _E3 , r _E4 ) are determined by the relations:

where φ _t = 26 mV is the temperature potential.

Therefore, in the medium frequency range for the control unit of FIG. 3, the voltage gains of the first and second channels are the same

where R _n.8 , R _n.10 - equivalent load resistance in the circuit of outputs 8 and 10.

If the control voltage U _y increases, then a current appears in the resistor 18

where R ₁₈ is the resistance of the resistor 18.

Therefore, the total current of the emitter of transistor 4 decreases, and the emitter of transistor 3 increases:

Therefore, taking into account (3) and (4) when R ₁₈ >> r _e the transmission coefficients of the channels will be determined by the formulas

or

остается постоянным:Thus, in the inventive two-channel VU with U _y > 0, the transmission coefficient of the first channel increases, and the second decreases in proportion to U _y . Moreover, the product K _y1 · K _y2 for

remains constant:

These theoretical conclusions are confirmed by the results of computer simulation (Fig.7, Fig.8).

Thus, the proposed device has a significant advantage compared with the prototype and can be used in analog devices requiring antiphase control of the transmission coefficients of the gain channels.

Information sources

1. Tytar, A.D. Active RC filter with indirect tuning based on two-link low-pass filters and high-pass filters [Text] / DD Tytar, AI Kalyakin // Electoral systems with feedback: inter-university thematic scientific collection. - Issue 1. - Taganrog, 1973. - S.100-104.

2. Prokopenko NN Controlled amplifiers for filters with indirect frequency tuning [Text] / N.N. Prokopenko // Electoral systems with feedback: inter-university thematic scientific collection. - Issue 1. - Taganrog, 1973. - S.119-122.

3. US Patent Application No. 2007/0090876.

4. US Patent Application No. 2006/0232334.

5. US patent No. 4.227.256.

6. US patent No. 6.958.653.

7. US patent No. 6.480.066.

8. US Patent No. 4,331.929.

9. US patent application No. 2004/0251955.

10. US patent application No. 2005/0052239.

11. US patent No. 6.958.653 fig.3.

12. US patent No. 6.956.435.

13. EP patent No. 1,369.992.

14. US patent application No. 2005/0099232.

15. US patent No. 7.091.786 fig. 1.

Claims (2)

1. Two-channel controlled AC amplifier containing a source of input (1) and control (2) signals, the first (3) and second (4) control transistors, the first (5) and second (6) output transistors, the bases of which are combined, the collector the first (5) output transistor is connected to the first (7) load circuit and the output (8) of the first amplification channel, the collector of the second (6) output transistor is connected to the second (9) load circuit and the output (10) of the second amplification channel, emitter of the first ( 5) the output transistor is connected to the first (11) current stabilizing engine by a pole, the emitter of the second (6) output transistor is connected to the second (12) current-stabilizing two-terminal device, characterized in that the input signal source (1) is connected to the combined bases of the first (5) and second (6) output transistors, the control signal source (2) is connected between the bases of the first (3) and second (4) control transistors, the emitter of the first (3) control transistor is connected to the emitter of the first (5) output transistor through the first (13) isolation capacitor, the emitter of the second (4) control transistor is connected to em the second (6) output transistor through the second (14) isolation capacitor, and the emitters of the first (3) and second (4) control transistors are connected to the corresponding first (15) and second (16) outputs of the additional circuit (17) for establishing the static mode of the first (3) and second (4) control transistors. 2. The device according to claim 1, characterized in that the static mode establishment circuit (17) contains an auxiliary resistor (18) connected between its first (15) and second (16) outputs, as well as the first (19) and second (20) ) additional current-stabilizing two-terminal connected with its corresponding first (15) and second (16) outputs.

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