JPH04343505A - Four quadrant multiplying circuit - Google Patents

Abstract

PURPOSE:To make it possible to drive this four quadrant multiplying circuit by a low constant voltage source by constituting transistors(TRs) of two vertical stacking stages. CONSTITUTION:A constant voltage is supplied from a constant voltage source to four differential amplifier pairs respectively formed by TRs 11, 12, TRs 13, 14, TRs 15, 16, and TRs 17, 18 and respectively grounded through resistors 25, 26 and a TR 38 and resistors 28, 29 and a TR 30. An input voltage Vin1 from input terminals 20, 21 is supplied to the bases of the TRs 11, 15 and TRs 12, 18 and an input voltage Vin2 from input terminals 22, 23 is supplied to the bases of the TRs 12, 13 and TRs 16, 17. Then an output from the 1st differential circuit and a reverse phase output from the 2nd differential circuit are added to output terminals S1, S2 through the collectors of the differential pairs and only a multiplied component Vo of voltages Vin1, Vin2 excluding the voltage components Vin1, Vin2 themselves is outputted. Consequently the four quadrant multiplier capable of operating even under the low voltage source <=2.4V by means of the TR constitution of two vertical stacking stages and having linearity and a dynamic range in a wide output range can be obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-phenomenon multiplication circuit that obtains a four-phenomenon multiplication output for two analog input signals in a modulation/demodulation circuit used in radio transmitting/receiving circuits and the like.

0002

2. Description of the Related Art FIG. 7 is a circuit diagram showing an example of the configuration of a conventional four-phenomenon multiplier circuit. In the figure, the bases of transistors 71 and 72 forming a differential amplifier circuit are connected to one input terminal 85 and 86. The collectors of the transistors 71 and 72 are connected to the cathodes of diodes 73 and 74, respectively, and the anodes of the diodes 73 and 74 are both connected to a constant voltage source 98 via a resistor 75. Also,
The emitters of transistors 71 and 72 are connected to the collectors of transistors 76 and 77, respectively, and via a resistor 78.

Transistors 81 and 82 and transistors 83 and 84 form a differential pair, with the bases of transistors 81 and 84 connected to the collector of transistor 71, and the bases of transistors 82 and 83 connected to the collector of transistor 72. Ru. Transistor 81, 8
The emitters of transistors 83 and 84 are connected to the collector of transistor 87, and the emitters of transistors 83 and 84 are connected to the collector of transistor 88. Transistor 87, 8
The emitters of transistors 8 and 8 are connected to the collectors of transistors 89 and 90, respectively, and are also connected via a resistor 91. Further, each base of the transistors 87 and 88 is
It is connected to the other input terminals 92 and 93. The collectors of transistors 81 and 83 and the collectors of transistors 82 and 84 are connected to output terminals 94 and 95, respectively, and to a constant voltage source 98 via resistors 96 and 97.

a transistor 102 whose collector and base are connected to a constant voltage source 98 via a resistor 101;
Transistors 76, 77, 89, and 90 whose bases are connected to the base of transistor 102, and transistor 7
Resistors 103, 104, 105, 106 connected between each emitter of 6, 77, 89, 90, 102 and ground
107 constitutes a constant current source using a current mirror circuit.

The diode differential circuit on the left shown here is
This circuit converts the input voltage Vx at input terminals 85 and 86, and generates an intermediate voltage V1 between diodes 93 and 94. At this time, the nonlinearity introduced into the input signal Vx when generating the intermediate voltage V1 from the input voltage Vx is caused by the differential pair (transistors 81, 82 and transistor 83).
, PP) shows the inverse characteristics of the nonlinearity associated with the base-emitter junction. Therefore, the output voltage Vo obtained at the output terminals 94 and 95 is proportional to the linear product of the input voltage Vx at the input terminals 85 and 86 and the input voltage Vy at the input terminals 92 and 93.

Resistors 78 and 9 serve as emitter negative feedback resistances.
1 converts input voltages Vx and Vy into differential currents Ix and Iy
When linearly converted into and each resistance value is Rx, Ry,
Ix = Vx /Rx... (1) I
y=Vy/Ry (2). Here, in order to make the voltage-current change at the input terminal more linear, each resistance value Rx, Ry is set as Rx >> Vt /I1 (3) where Vt is the thermal voltage of the transistor.
Ry >>Vt/I2... (4)
must be selected so as to satisfy the following conditions. Note that I1 and I2 are currents flowing through transistors 76 and 77 and transistors 89 and 90, respectively, which constitute constant current sources.

[0007] Therefore, the output voltage Vo is
The resistance value of 6,97 is set as RL, and the transistors 81 to 8
The current flowing in each collector of 4 is I6, I8, I7
, I5, then Vo = RL・((I6+I7)-(I5+I8))
... (5). Also, each branch current of the circuit is given by I6/(I2+Iy)=I5/(I2
-Iy)=(I1+Ix)/2・I1... (
6) and I8/(I2+Iy)=I7/(I2-Iy)=(
I1-Ix)/2・I1... (7) There is a relationship. Here, equations (6) and (7) are replaced by (5)
Substituting into the formula and eliminating I6 to I8, Vo =
2・RL・(Ix・Iy)/I1... (8) Furthermore, since Ix and Iy have a linear relationship with the input voltages Vx and Vy, Vo = K1・Vx・Vy
... It can be expressed as (9). In addition, K1=2・R
L/(I1・Rx・Ry).

[0008] Through such an operation, it is possible to obtain a multiplication output of four linear phenomena for two inputs.

[0009]

By the way, in such a conventional configuration, if each constant current source of the diode differential circuit on the left side and the Gilbert cell section on the right side is configured as a current mirror configuration using transistors and resistors, the entire multiplier circuit becomes The number of vertically stacked transistors is three. Therefore, in order to operate this four-phenomenon multiplier circuit correctly, the constant voltage source 9
It is necessary to make the voltage value of 8 greater than 2.4V.

That is, in the conventional configuration, under a low constant voltage source of 3 V or less, such as a multiplier circuit used in a modulation/demodulation circuit of a mobile radio transmitter/receiver, linearity over a wide input/output level range and wide dynamic range cannot be achieved. It was difficult to secure a microwave. Furthermore, under a constant voltage source of 2.4 V or less, a signal with an appropriate bias could not be input to the diode differential circuit, and the Gilbert cell section could not operate as a four-phenomenon multiplier circuit.

An object of the present invention is to provide a four-phenomenon multiplier circuit that can operate under a low constant voltage source of 2.4V or less.

0012

[Means for Solving the Problems] The invention according to claim 1 takes in one of a first differential input signal and a second differential input signal, and obtains a multiplication component of each differential input signal and each difference. a first differential amplifier circuit that outputs a dynamic input signal component; and a first differential amplifier circuit that takes in the other of the first differential input signal and the second differential input signal, and outputs the multiplication component and each difference of each differential input signal; A second differential amplifier circuit outputs a dynamic input signal component, and the opposite phase components of each output signal of the first differential amplifier circuit and the second differential amplifier circuit are added together, and each of the differential input signal components is It is characterized by outputting only the multiplication component of the signal.

[0013] The invention according to claim 2 is a diode differential circuit having a current source configuration, in which the first differential input signal and the second differential input signal input to the four-phenomenon multiplication circuit according to claim 1 are It is characterized by being supplied through.

[0014]

[Operation] According to the invention described in claim 1, in the first differential amplifier circuit and the second differential amplifier circuit, a multiplication component of two input signals and each input signal component are obtained. By configuring the circuit symmetrically and adding the antiphase components of each output signal at the output stage, each input signal component can be canceled and only the multiplied component can be output.

That is, by supplying two input signals at the same bias level and using a current source current source, the number of vertically stacked transistors can be reduced to two. According to the second aspect of the present invention, the diode differential circuit connected to the input stage also has a current source configuration, thereby making it possible to increase the number of vertically stacked transistors to two.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a circuit diagram showing an embodiment of the invention as set forth in claim 1. In the figure, transistors 11,
12, transistors 13, 14, transistors 15, 1
6. The transistors 17 and 18 form a differential pair, with the bases of the transistors 11 and 15 connected to the input terminal 20, the bases of the transistors 14 and 18 connected to the input terminal 21, and the bases of the transistors 12 and 13 connected to the input terminal 20. Each base is connected to input terminal 22, and each base of transistors 16 and 17 is connected to input terminal 23. transistor 1
The emitters of transistors 1 and 12 and the emitters of transistors 13 and 14 are connected via resistors 25 and 26, and the collector of transistor 27 is connected to the connection point of each resistor. The emitters of transistors 15 and 16 and the emitters of transistors 17 and 18 are connected via resistors 28 and 29, and the collector of transistor 30 is connected to the connection point of each resistor. The collectors of transistors 11 and 12 are connected to the collectors of transistors 17 and 18, and the collectors of transistors 13 and 14 are connected to the collectors of transistors 15 and 16. Output terminals 31 and 32 are connected to each connection point, and
A constant voltage source 35 is connected via resistors 33 and 34.

A transistor 37 whose collector and base are connected to a constant voltage source 35 via a resistor 36, transistors 27 and 30 whose bases are connected to the base of the transistor 37, and each of the transistors 27, 30, and 37. Resistors 38, 39, 4 connected between emitter and ground
0 constitutes a constant current source using a current source.

The analog multiplication operation of this embodiment will be explained below with reference to FIG. 2 showing the left half of the embodiment configuration of FIG. 1, and FIG. 3 showing its equivalent half circuit. In FIG. 3, Vin1 and Vin2 are the input voltages of the input terminals 20 and 21, respectively. RE is the resistance value of resistors 25 and 26,
RL is the resistance value of the resistors 33 and 34, and RS is the impedance of the constant current source. rπ is a resistance that satisfies rπ=dVBE/dIB, where VBE is the base-emitter voltage of the transistor and base current IB, and V1
and V2 is the voltage across rπ of each transistor. gm1 and gm2 are the transconductances of each transistor, I0 is the current flowing through the resistors 33 and 34, iX and iy are the currents flowing through each rπ, and V
o is the output voltage taken out to the output terminals 31 and 32.

[0019] Here, Vin1=V1+(iX+gm1・V1)・RE
...(10) V
in2 =V2+(iy+gm2・V2)・(RE+R
S) ...(11) V1 = iX
・rπ
...(12) V2
=iy・rπ
…(13)
Vo =-(gm1・V1+gm2・V2)・RL
...(14). Therefore, when V1 is rearranged using equations (10) and (12), V1 = Vin1 / (1 + (1/rπ + gm1)
RE ) ...(15) becomes (11)
When V2 is rearranged using formula and formula (13), V2 = Vin2 / (1 + (1/rπ + gm2)
(RE+RS))...(16). (1
4) Expressing the equation using the thermal voltage Vt of the transistor, Vo = -(I1・V1/Vt+I2・V2/Vt
)・RL=−(I0・V1/Vt+I2・
V2/Vt-gm2・V1・V2/Vt)・RL


...(17). Substituting equations (15) and (16) into equation (17) and sorting it out, Vo = -(I0/Vt)・Vin1/(1+(1
/rπ+gm1)RE) +(I2/V
t)・Vin2/(1+(1/rπ+gm2)(RE+
RS)) -(gm2/Vt)・Vin
1/(1+(1/rπ+gm1)RE)
・(Vin2/(1+(1/rπ+gm2)(R
E+RS)) ≒-(1+gm2/gm1)
RL・Vin1/RE-RL・Vin2/(RE+RS
) +RL・Vin1・Vin2/V
t・gm1・RE(RE+RS)…(18
). Therefore, Vo = -α・Vin1−β・Vin2+γ・Vi
n1·Vin2 (19). In addition, α=(1+gm2/gm1)RL/REβ=RL/(R
E+RS) γ=RL/Vt・gm1・RE(RE+RS). In this way, the output voltage Vo taken out to the output terminals 31 and 32 includes the multiplication component (γ・Vin) of the two input voltages.
1・Vin2), each input signal component (−α・Vi
n1, -β·Vin2).

In the circuit of FIG. 1, the resistor 25
, 26 and the pair of resistors 28, 29, the output is, for example, 2 of the circuit in FIG.
It can be thought of as a signal component obtained by adding the output when a positive signal is input to each input and the output when a negative signal is input at the output stage. That is, in equation (19), Vin
1 = Vc1, Vin2 = Vc2, and the output at that time is Vo1, then Vo1 = -α・Vc1−β・Vc2+γ・Vc1・
Vc2...(20). Also, in equation (19), Vin1 = -Vc1, Vi
If n2 = -Vc2 and the output at that time is Vo2, then Vo2 = α・Vc1+β・Vc2+γ・Vc1
・Vc2...(21).

At this time, Vo1 in equation (20) and (21
) Adding Vo2 of the formula, Vo1+Vo2=2γ・Vc1・Vc2
…(22
). As a result, the circuit output of FIG. The Vin1 and Vin2 components of the output voltage Vo are completely removed, and the input terminals 55, 56
Only the multiplication component of the input voltage Vin1 of the input terminals 62 and 63 and the input voltage Vin2 of the input terminals 62 and 63 can be obtained.

In such a configuration, even if the transistor constituting the constant current source is included, the number of vertically stacked transistors is two, making it possible to operate under a low voltage source. FIG. 4 is a circuit diagram showing another embodiment of the invention according to claim 1. The feature of this embodiment is that the resistors 25 and 26 and the resistors 28 and 2 in the configuration shown in FIG.
9 are replaced with resistors 41 and 42, respectively, and 2
current source current sources (transistors 27, 30,
The configuration is such that the resistors 38, 39) are replaced with four current source current sources (transistors 43-46, resistors 47-50). Note that the operation as a four-phenomenon multiplier circuit is the same as that described using FIGS. 1 to 3.

With this configuration, it is possible to reduce the voltage drop caused by the resistors 25, 26, 28, and 29. In other words, even lower voltage operation can be realized as a four-phenomenon multiplier circuit. FIG. 5 is a circuit diagram showing the configuration of an embodiment of the invention according to claim 2. The configuration of this example is two of the four-phenomenon multiplier circuit shown in FIG.
The device is characterized in that each of the two input sides is provided with a diode differential circuit whose input side is configured as a current source.

The configuration of the diode differential circuit (labeled a) on the input side of the input terminals 20 and 21 will be described below, but the configuration of the diode differential circuit (labeled b) on the input side of the input terminals 22 and 23 will be described below. The same is true. That is, the bases of the transistors 51a and 52a are connected to one input terminal 53a,
54a. The emitter of transistor 51a is connected to the collector and base of transistor 55a and the base of transistor 56a, and the emitter of transistor 52a is connected to the base of transistor 56a.
The emitter of is connected to the collector and base of transistor 57a and the base of transistor 58a. The emitters of the transistors 56a, 58a are connected via a resistor 59a, and the emitters of the transistors 55a, 56a, 5
The emitters of 7a, 58a are resistors 60a, 61a, 62
It is connected to ground via a and 63a. The collectors of the transistors 56a and 58a are each connected to a diode 64.
a, 65a, and is also connected to the input terminals 20, 21 of the four-phenomenon multiplier circuit. Collectors of transistors 51a and 52a and diode 64a,
The anode of 65a is connected to constant voltage source 35.

With such a configuration, the transistor 11
14 and the output stage of transistors 15 to 18, the output of the diode differential circuit having opposite characteristics is input to input terminals 20, 21 and 22, 23.
By incorporating the four-phenomenon multiplication circuit into the four-phenomenon multiplication circuit shown in FIG. Note that this diode differential circuit can also operate under a low voltage source of 2.4 V or less by using a current source configuration in which the number of vertically stacked transistors is two.

FIG. 6 is a circuit diagram showing another embodiment of the invention according to claim 2. The feature of this embodiment is that the configuration shown in FIG. 4 is used as the four-phenomenon multiplier circuit. That is, each pair of resistors 25, 26 and resistors 28, 29 in the configuration shown in FIG. ) with four current source current sources (transistors 43-46, resistors 47-50
). Note that the operation as a four-phenomenon multiplier circuit is the same as that described using FIGS. 1 to 3 and FIG. 5.

With this configuration, it is possible to reduce the voltage drop caused by the resistors 25, 26, 28, and 29. That is, even lower voltage operation can be realized as a four-phenomenon multiplier circuit including a diode differential circuit. Note that in the embodiments described above, an example was shown in which an NPN transistor was used as a bipolar transistor, but the present invention can be similarly implemented using a PNP transistor.

[0028]

[Effects of the Invention] As explained above, in the present invention, the number of vertically stacked transistors can be two.
Even a constant voltage source of 2.4 V or less can sufficiently perform the multiplication operation. Therefore, compared to the conventional four-phenomenon multiplication circuit, it is possible to achieve linearity over a wide input/output level range and a wide dynamic range.

Furthermore, when used as a mixer in a modulation/demodulation circuit for a mobile radio transmitter/receiver, low voltage operation is possible, so a great effect can be obtained in reducing power consumption.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the invention according to claim 1.

FIG. 2 is a circuit diagram showing the left half of the embodiment configuration of FIG. 1;

FIG. 3 shows an equivalent half-circuit of the circuit of FIG. 2;

FIG. 4 is a circuit diagram showing another embodiment of the invention according to claim 1;

FIG. 5 is a circuit diagram showing the configuration of an embodiment of the invention according to claim 2;

FIG. 6 is a circuit diagram showing a configuration of another embodiment of the invention according to claim 2.

FIG. 7 is a circuit diagram showing a configuration example of a conventional four-phenomenon multiplication circuit.

[Explanation of symbols]

11-18, 27, 30, 37 transistor 20-
22 Input terminals 25, 26, 28, 29, 33, 34, 36, 38-4
0 Resistors 31, 32 Output terminal 35 Constant voltage sources 41, 42, 47-50 Resistors 43-46 Transistors 51, 52, 55-58 Transistors 53, 54
Input terminals 59-63 Resistors 64, 65 Diodes 71-74, 76, 77, 81-84, 89, 90, 1
02 Transistor 73, 74 Diode 75, 78, 91, 96, 97, 101, 103-10
7 Resistor 85, 86, 92, 93 Input terminal

Claims (2)

[Claims] 1. A first differential amplifier that takes in one of a first differential input signal and a second differential input signal and outputs a multiplication component of each differential input signal and each differential input signal component. a circuit, and a second differential amplifier that takes in the other of the first differential input signal and the second differential input signal and outputs a multiplication component of each differential input signal and each differential input signal component. circuit and
Four-phenomenon multiplication characterized in that antiphase components of the output signals of the first differential amplifier circuit and the second differential amplifier circuit are added together, and only the multiplied components of the respective differential input signals are output. circuit. 2. Supplying the first differential input signal and the second differential input signal input to the four-phenomenon multiplication circuit according to claim 1 via a diode differential circuit having a current source configuration. Features 4-phenomenon multiplication circuit