RU2458456C1 - Analog mixer of two signals - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: analog mixer of two signals comprises input transistors from the first to the fourth, a "voltage-current" converter, the first and second dipoles of collector load, the first and second output transistors, the first and second sources of reference current, the first and second feedback resistors.

EFFECT: provision of low values of a permanent component of output cophased voltage in an AM, its higher stability at temperature and other external impacts, and also technological errors to manufacture elements, higher coefficient of AM amplification for main harmonics of its output voltage.

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Description

The present invention relates to the field of radio engineering and communications and can be used in the structure of radio receivers of the high and microwave ranges.

In modern telecommunication systems, various modifications of the Gilbert cell [1-24] are used as analog mixers of two signals (AS) (the term “Gilbert cell” is widely used in microelectronics, see, for example, patent No. 7.054.609, and means “ multiplying ”architecture based on two differential stages with cross-connection of input transistor collectors).

To match the potentials of the outputs of the classical Gilbert AS with the subsequent functional unit in known communication devices, output emitter repeaters are used (patents US 7,403,758 fig.2, US 5.684.419 fig.3, etc.), which, however, introduce additional static errors of signal conversion.

The closest prototype of the claimed device is an analog mixer of two signals of figure 1, presented in the patent US 5.684.419 fig.3 (this architecture is also present in the patent US 7.403.758 fig.2 and others). It contains the first 1 and second 2 input transistors, the bases of which are connected to the first 3 input of the channel “X”, the third 4 and fourth 5 input transistors, the bases of which are connected to the second 6 input of the channel “X”, a voltage-current converter 7, having the first 8 and second 9 inputs of the channel “Y”, as well as the first 10 and second 11 current outputs, the first 10 current output of the voltage-current converter 7 being connected to the combined emitters of the first 1 and third 4 input transistors, and the second 11 current the output of the voltage-current Converter 7 is connected to connected emitters of the second 2 and fourth 5 input transistors, the first 12 collector load two-pole connected between the first 13 bus of the power supply and the combined collectors of the second 2 and third 4 input transistors connected to the base of the first 14 output transistor, the second 15 collector load two-pole connected between the first 13 bus power supply and the combined collectors of the first 1 and fourth 5 input transistors associated with the base of the second 16 output transistor, the first 17 reference current source, connected between the emitter of the first 14 output transistor connected to the first 18 output of the device and the second 19 power supply bus, the second 20 is a reference current source connected between the emitter of the second 16 output transistor connected to the second 21 output of the device and the second 19 power supply bus the emitter circuit of the voltage-current Converter 7, and the collectors of the first 14 and second 16 output transistors are connected to the first 13 bus power sources.

A significant drawback of the known mixer is that it has an unstable output common-mode voltage level (U _o.s. = (U _{o.s. 1} + U _o.s.2 ) / 2. Moreover, the numerical values of U _o.s.sub. significantly differ from zero and depend on from temperature and mode changes in the AC circuit (supply voltages, dispersion of the resistance of the load resistors, currents of the reference current sources, etc.) This does not allow the efficient use of the dynamic range of the AC, which takes on the greatest value at U _o.s. = 0.

The main objective of the invention is to ensure in the AC small values of the constant component of the output common-mode voltage U _o.c ≈ 0 and its high stability under temperature and other external influences, as well as technological errors in the manufacture of elements.

An additional task is to increase the gain (conversion factor of the input signals f _x , f _y ) AC for the main harmonics of its output voltage.

The tasks are solved by the fact that in an analog mixer of two signals containing the first 1 and second 2 input transistors, the bases of which are connected to the first 3 input of the channel “X”, the third 4 and fourth 5 input transistors, the bases of which are connected to the second 6 input of the channel “ X ", the voltage-current converter 7, having the first 8 and second 9 inputs of the channel" Y ", as well as the first 10 and second 11 current outputs, the first 10 current output of the voltage-to-current converter 7 connected to the combined emitters of the first 1 and third 4 input transistors, and the second 11 current output of the voltage-current converter 7 is connected to the combined emitters of the second 2 and fourth 5 input transistors, the first 12 two-terminal collector load connected between the first 13 bus of the power source and the combined collectors of the second 2 and third 4 input transistors associated with the base the first 14 output transistor, the second 15 two-pole collector load connected between the first 13 bus power supply and the combined collectors of the first 1 and fourth 5 input transistors connected and with the base of the second 16 output transistor, the first 17 is a reference current source connected between the emitter of the first 14 output transistor connected to the first 18 output of the device and the second 19 power supply bus, the second 20 is a reference current source connected between the emitter of the second 16 output transistor with a second 21 output of the device and a second 19 power supply bus connected to the emitter circuit of the voltage-current converter 7, and the collectors of the first 14 and second 16 output transistors are connected to the first 13 bus of the source power supply, new elements and communications are provided - the first 18 device output is connected to the first 3 input of the “X” channel through the first 22 feedback resistor, and the second 21 device output is connected to the first 3 input of the “X” channel through the second 23 feedback resistor.

The drawing of Fig. 1 shows a diagram of an AC prototype, in which the voltage-current converter 7 is shown as a functional unit implemented according to traditional schemes, for example, on the basis of a differential cascade with local negative feedback (Fig. 8).

In the drawing of figure 2 presents a diagram of the inventive speakers in accordance with the claims.

The drawing of figure 3 presents a diagram of an AC prototype in a Cadance environment on models of SiGe integrated transistors.

Figure 4 shows a diagram of the proposed mixer in a Cadence environment on SiGe integrated transistor models when the output currents of the converter 7 change by an amount of Ivar = 500 μA (channel control "Y": I4 = 2 mA + Ivar; I5 = 2 mA-Ivar )

The drawing of figure 5 shows the dependence of the output differential voltage of the mixer of figure 4 from the voltage on the channel "X" at different voltages (control currents I _var ) of the channel "Y".

The drawing of Fig.6 shows the dependence of the voltage gain module K _{y of the} compared mixers of Fig.3 and Fig.4 on the control current (I _var ) along the channel "Y".

The drawing of Fig.7 shows a graph of the error of the multiplication of two signals of the compared circuits of Fig.3 and Fig.4 in the mode of a controlled amplifier.

The drawing of Fig. 8 shows a diagram of an AC prototype with a real implementation of the voltage-current converter 7 based on additional differential stages on transistors Q43, Q42, Q44, Q45.

The drawing of Fig.9 shows a diagram of the inventive speakers with the same design of the Converter "voltage-current" 7, as in the circuit of Fig.8.

The drawing of Fig. 10 shows the dependence of the amplitude of the output harmonic f _x + f _y 250 MHz on the control voltage of the channel "Y" of the compared circuits of Fig. 8, Fig. 9 with f _x = 100 MHz, f _y = 150 MHz.

The inventive mixer of two signals of figure 2 contains the first 1 and second 2 input transistors, the bases of which are connected to the first 3 input of the channel "X", the third 4 and fourth 5 input transistors, the bases of which are connected to the second 6 input of the channel "X", the converter voltage-current "7, having the first 8 and second 9 inputs of the channel" Y ", as well as the first 10 and second 11 current outputs, and the first 10 current output of the voltage-current converter 7 is connected to the combined emitters of the first 1 and third 4 input transistors, and the second 11 current output of the converter I "voltage-current" 7 is connected to the combined emitters of the second 2 and fourth 5 input transistors, the first 12 two-pole collector load connected between the first 13 bus power supply and the combined collectors of the second 2 and third 4 input transistors connected to the base of the first 14 output transistor , the second 15 collector load two-pole connected between the first 13 bus of the power supply and the combined collectors of the first 1 and fourth 5 input transistors connected to the base of the second 16 output trans ora, the first 17 reference current source connected between the emitter of the first 14 output transistor connected to the first 18 output of the device and the second 19 bus of the power source, the second 20 reference current source connected between the emitter of the second 16 output transistor connected to the second 21 output of the device and the second 19 bus power source associated with the emitter circuit of the Converter "voltage-current" 7, and the collectors of the first 14 and second 16 output transistors are connected to the first 13 bus power sources. The first 18 device output is connected to the first 3 input of the “X” channel through the first 22 feedback resistor, and the second 21 device output is connected to the first 3 input of the “X” channel through the second 23 feedback resistor.

Consider the operation of the AS figure 2.

при идентичных транзисторах 1, 2, 4 и 5 за счет отрицательной обратной связи по синфазному сигналу через транзисторы 1, 2 и 16, 14 уровень статических напряжений на выходах АС 21 и 18 относительно общей шины также близок к нулю:In the static mode (when the input voltages of the channels “X” and “Y” are equal to zero, u _x = 0, u _y = 0,

with identical transistors 1, 2, 4 and 5 due to negative feedback on the common mode signal through transistors 1, 2 and 16, 14, the level of static voltages at the AC outputs 21 and 18 relative to the common bus is also close to zero:

where I ₂₂ , I ₂₃ - static currents in resistors 22 and 23;

I ₂₂ ≈I ₂₃ ≈I _b1 ≈ _b2 = 10 ÷ 20 μA (for typical integrated transistors and their static currents at a base current gain of β ₁ ≈β ₂ = 80 ÷ 100);

I ≈I _{b1 b2} - base currents of transistors 1 and 2.

If you choose R ₂₃ = R ₂₂ = 200 ÷ 500 Ohms, then from (1), (2) it follows that in the claimed AC U _{output with} ≈2 ÷ 5 mV. This allows you to directly connect the outputs 18 and 21 of the AS of figure 2 to the subsequent functional node of the communication device in which the speaker is used, and not to worry about matching their static modes.

It should also be noted that in the circuit of Fig. 2, the two-terminal load 12 and 15 can be made in the form of transistor current sources, which significantly increases the gain of the speaker, as well as its conversion factor of the amplitude u _x to the amplitude of the output harmonics with frequencies f _x + f _y , f _y -f _x . This mode is not possible in the AC prototype of figure 1, since the use of current sources as bipolar load 12 and 15 will lead to saturation (or cutoff) of the transistors 1-5 and, consequently, to the disruption of the device. In the inventive speaker with current sources as two-terminal 12, 15 provides an active mode of transistors 1 ÷ 5 negative feedback circuit.

Further, as transistors 16 and 14 in the circuit of FIG. 2, composite bipolar transistors or their field analogs can be used (to reduce the effect of low resistance R _n = 50 Ohm loads). This also will not affect the operation of the circuit of figure 2 due to the presence of negative feedback.

The proposed circuit has the basic properties of the classical Gilbert cell of Fig. 5, Fig. 6, Fig. 7, but is characterized by a close to zero level of output static voltages. At the same time, due to the use of 12 and 15 current sources as two-terminal devices, the limiting conversion coefficients of the AC circuit of Fig. 2 are increased (in comparison with the prototype) by more than an order of magnitude.

The sinusoidal voltages of the first mixed signal u _x (at the input 6 of the channel “X”) and the second mixed signal u _y (at the inputs of the channel “Y” 8, 9) are “multiplied” in the traditional way in the Gilbert cell 1. This is indicated by the drawings of FIG. 5 indicative of the "multiplying" properties of the claimed device.

The proposed technical solution has significant advantages in comparison with the classic Gilbert signal mixers, protected by more than 300 patents of the leading microelectronic companies in the world.

BIBLIOGRAPHIC LIST

1. Patent application US No. 2008/113644

2. Patent application US No. 2006/0232334, fig.1

3. US patent No. 4.965.528, fig.2

4. US patent No. 6.744.308

5. US patent No. 7.633.328

6. US patent No. 7.110.740

7. Patent application US No. 2009/0085663, fig.2

8. US patent No. 7.514.981, fig.1

9. Aut. St. USSR No. 642843

10. US patent No. 5.933.771, fig.2

11. US patent No. 6.016.079, fig.4

12. US patent No. 5.057.784

13. US patent No. 4.286.226

14. Patent application US No. 2008/0261552, fig. 1

15. US patent No. 6.373.345, fig.2

16. Patent application US No. 2010/0164595, fig.2

17. Patent application US No. 2010/0141325

18. US patent No. 4.344.188, fig. 1, fig. 3

19. Patent EP 1455441

20. US patent No. 7.812.775, fig.20, fig.16

21. Patent EP 2235559, fig. 3

22. US patent No. 7.676.212, fig.2

23. Patent application US No. 2008/0180156, fig. 1, fig. 5

24. US patent No. 5.825.231, fig.1

Claims (1)

An analog mixer of two signals containing the first (1) and second (2) input transistors, the bases of which are connected to the first (3) input of the channel “X”, the third (4) and fourth (5) input transistors, the bases of which are connected to the second ( 6) the input of channel "X", the voltage-current converter (7) having the first (8) and second (9) inputs of the channel "Y", as well as the first (10) and second (11) current outputs, the first (10) the current output of the voltage-current converter (7) is connected to the combined emitters of the first (1) and third (4) input transistors, and the second (11) current output the voltage-current converter (7) is connected to the combined emitters of the second (2) and fourth (5) input transistors, the first (12) collector bipolar connected between the first (13) power supply bus and the combined collectors of the second (2) and a third (4) input transistor connected to the base of the first (14) output transistor, a second (15) collector load two-pole connected between the first (13) power supply bus and the combined collectors of the first (1) and fourth (5) input transistor with base the second (16) output transistor, the first (17) reference current source connected between the emitter of the first (14) output transistor associated with the first (18) output of the device, and the second (19) power supply bus, the second (20) reference current source connected between the emitter of the second (16) output transistor associated with the second (21) output of the device and the second (19) power supply bus connected to the emitter circuit of the voltage-current converter (7), the collectors of the first (14) and second (16) output transistors connected to the first (13) bus power sources, characterized in that the first (18) output of the device is connected to the first (3) input of the channel “X” through the first (22) feedback resistor, and the second (21) output of the device is connected to the first (3) input of the channel “X” »Through the second (23) feedback resistor.

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