JPS5922597Y2 - multiplication circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a four-quadrant multiplication circuit in a communication device.

Conventionally, this type of circuit (balanced modulator, for example) had a problem with linearity because the nonlinear portion of the diode was also within the usable range, and had the disadvantage that when one input was close to θ, waveform distortion became large.

The purpose of the present invention is to provide a multiplication circuit with a simple circuit configuration and excellent linearity.

A detailed explanation will be given below according to the drawings.

FIG. 1 is a block diagram of the present invention.

In the figure, 1 and 2 are human signal terminals, 3 is an in-phase branch circuit (or anti-phase branch circuit), 4 and 4' are current-controlled linear variable resistance elements, 5 is a differential amplifier circuit, and 6 is an anti-phase synthesis circuit ( or an in-phase synthesis circuit), and 7 is an output signal terminal.

Now, if a signal of 2E1 is inputted to the input terminal 1, the outputs of the branch circuits 3 will each become E1 (in the case of in-phase branching), and these will pass through the variable resistance elements 4 and 4'.

The variable resistance elements 4 and 4' are elements whose resistance values change linearly depending on the flowing current. This current is controlled by the differential amplifier 5, and when the input terminal 2 is 0, the two current values of the differential amplifier 5 are They are adjusted so that they are equal (the current value at this time is assumed to be 1).

Here, when the signal E2 is applied to the input terminal 2, the two currents of the differential amplifier 5 become unbalanced.
An increase or decrease of (0<k<1) occurs.

As a result, the resistance value of the variable resistance element 4 increases or decreases proportionally, and the output of the branch circuit 3 changes to (1+
k) E, and (1-k)E, (where 1
; constant of proportionality).

When these two are synthesized in reverse phase, Kl (1+k) E1+ (-Kl (1-k)
E, )-2K.

kEl...(1).

Here, since -2E2 (where 2: proportionality constant) is rewritten, formula (1) becomes 2 to 1, 2E1E2 = KE1E
2 (K=2 to 1 to 2), and the block diagram in Figure 1 is as follows.
It becomes a four-quadrant multiplication circuit for input signals E1 and E2.

Note that even if the input side is branched in anti-phase and the output side is combined in-phase, the same result will be obtained.

Figure 2 shows an embodiment of the present invention, showing the IF signal (70MH) at terminal 1.
z) and the baseband control signal at terminal 2.

This will be explained below. The emitter of transistor 30.31 is connected to negative voltage terminal 38 via variable resistor 32 and common constant current source 37 (consisting of transistor 33, resistor 34.35 and Zener diode 36).

The collector of transistor 30 is connected to the positive power supply terminal via choke 17, PIN diode 13.14, transformer 10.40, and chokes 15 and 16.

On the other hand, the collector of the transistor 31 is connected to the choke 18, P
It is connected to the positive power supply terminal 23 via an IN diode 11.12, a transformer 10.40, and a choke 15.16 to form a four-quadrant multiplication circuit.

19 to 21 are capacitors.

Now, when the input terminal 2 is 0 (ground), the base of the transistor 30 is also O, so the currents flowing to the collectors of the transistors 30 and 31 are equal.

At this time, the resistance values of the PIN diodes 11 to 14 are all equal, so the two signal levels of the input signal 1 to the transformer 40 are equal.

Since the transformer 40 is a reverse phase hybrid transformer, if the input signal levels are equal, the output will be 0 and one input will be 0.
It exhibits a multiplication characteristic in which the output becomes 0 when .

Next, when a signal is applied to the input terminal 2, the collector currents of the transistors 30 and 31 increase or decrease in proportion to the signal level, and as a result, the resistance values of the PIN diodes 11 to 14 also increase or decrease in proportion.

As a result, as explained with reference to FIG. 1, the output is proportional to the signal level of the input terminal 2, and exhibits a multiplication characteristic.

On the other hand, if the signal level of the input terminal 2 is constant, the resistance value of the PIN diode is constant and the output signal level is proportional to the signal level of the input terminal 1, so that it exhibits a multiplication characteristic for the input terminal 1 as well.

Therefore, the circuit of FIG. 2 becomes a four-quadrant multiplication circuit.

As explained above, since the current can be constantly passed through the current controlled variable resistance element and used at an operating point with good linearity, it has excellent linearity, and the circuit configuration is simple, so this automatic equalization transformer uses a large number of this circuit. It has the advantage of being applicable to parsal filters, etc.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention, and FIG. 2 is a specific example of a circuit diagram of the present invention. In the figure, 1, 2... input terminal, 3... in-phase branch circuit (or anti-phase branch circuit), 4... current control linear resistance element, 5... differential amplifier circuit, 6... Negative phase synthesis circuit (or in-phase synthesis circuit), 7...output terminal, 10.40
...Hybrid transformer, 11-14...PIN
Diode, 15, 16° 17, 18...Choke,
17-22... Capacitor, 30.31°33...
Transistor, 32... Variable resistor, 34.35...
・Resistor, 36... Zener diode, 37...
Constant current source, 23... positive power supply terminal, 38... negative power supply terminal.

Claims (1)

[Scope of utility model registration request] a multiplication circuit that multiplies a first signal and a second signal to generate a third signal; means for generating a current corresponding to the level of the second signal; current control linear variable resistance means □ for controlling the fourth and fifth signals with the current to generate sixth and seventh signals; and means for combining the sixth and seventh signals in opposite phase or in phase to generate the third signal.