JPS6020641A - Signal compression circuit device - Google Patents

Abstract

PURPOSE:To attain the temperature compensation of a diode by providing a voltage dividing type compressiong circuit comprising a resistor and a series circuit consisting of diodes of anti-parallel connection and a resistor to a signal compression circuit to make the input sensitivity curve variable easily. CONSTITUTION:When a sinusoidal wave Vi is inputted to a terminal A, a non-inverting input Vs of an amplifier 7 becomes Vs=kT/q.ln(ID/Is)+R4ID, where ID is a diode current and Is is a reverse current of diode. The 1st term of equation expressing Vs is dominant when ID(Vi) is small and the 2nd term is dominant when the ID(Vi) is large. The sensitivity curve of the compressing circuit changing from this logarithmic compression into linear range is changed by changing the value of resistors 1, 4. Further, the current is increased by DELTAID when the forward voltage of the diode is decreased because of temperature change, the Vs is about to increase by DELTAIDR4 by changing the resistor R4, resulting in that the circuit acts like compensating the change in the Vs due to temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a signal compressor for amplifying a voltage divided by a first resistor and a diode inserted in series with a second resistor inserted in series with the input part. This invention relates to a circuit device.

Conventional configurations and their problems In recent years, the development of semiconductor integrated circuits has been remarkable.
Although operational amplifiers and the like have become much cheaper than before, they are still more expensive components than resistors, diodes, etc.

Figure 1 shows a conventional signal compression circuit, 21 is a resistor, 22
is an amplifier with an inverting and non-inverting input, 23.24 is a diode for compressing the signal, 25 is a resistor for passing the diode current, 26 is a second stage input resistor, and 27 is an inverting and non-inverting input. In the amplifier, 28 is a resistor that determines the gain. Note that A is an input terminal and B is an output terminal.

Now, when a signal is applied to A, the signal current flows through the amplifier 22.
Since the input impedance of is high and the inverting input terminal is virtual ground, everything flows through the diode 23 (or 24) and flows into the output of the amplifier via the resistor, but here the inverting input terminal is virtual ground and oV. Therefore, the voltage at the connection point between the diode and the resistor 25 is the forward voltage VD of the diode, and is compressed logarithmically with respect to the input voltage. The signal at the connection point is transferred to the second stage inverting amplifier 27.
and output to output terminal B.

Therefore, this conventional circuit requires a large number of amplifiers, and furthermore, there are problems in that it is not easy to detect the temperature of the diode.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems, and aims to provide a signal compression circuit device that can easily correct characteristic changes due to temperature changes, and can also easily and inexpensively vary the input sensitivity curve. .

Structure of the Invention The present invention uses one end of a first resistor as an input, connects the cathode of the first diode, the anode of the second diode, and the positive phase input side of the amplifier to the other end of the resistor. and the cathode of the 26th diode are connected, and a second resistor is connected in series to allow temperature compensation and input sensitivity curve correction, the other terminal of said second resistor being connected to the circuit ground. A third . The compression circuit device is configured such that feedback is applied by a fourth resistor, and the output of the amplifier is used as the circuit output, and 22 diodes connected in parallel with the first resistor in both directions are connected in series, and By inserting the second resistor in series, temperature compensation can be easily performed without using an amplifier, and desired compression characteristics can be easily obtained.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention 2 will be described below with reference to FIG.

A is an input terminal, and B is an output terminal. A resistor 1 is connected between the input terminal A and the positive phase input side of the amplifier 7, and a parallel circuit of diodes 2 and 3 are connected in antiparallel to each other between the connection point between the resistor 1 and the positive phase input side of the amplifier 7 and the ground. A series circuit of resistor 4 is connected, and the inverting input side of amplifier 7 is grounded via resistor 5, and resistor 6 is connected between the output side and inverting input side of amplifier 7, and the output side is connected to output terminal B. It is connected.

With the above configuration, let the resistance values of resistor 1 and resistor 4 be R1 and R4, respectively8, and if a sine wave is applied to the intervention force, then the voltage value at a certain point in the sine wave is V. Then, the following voltage vs is applied to the positive phase input of the amplifier 7.

■8-kT/q111n (y/s) + R4ID Here, k is the current flowing through the diode, k is Boltzmann's constant, T is the absolute temperature, q is the amount of electron charge, and s is the reverse current of the diode. It is.

The first term of the voltage 8 becomes dominant when is small, that is, when vo is a small signal, and the second term becomes dominant when ID is large, that is, when vo is a small signal,
becomes dominant when is large, and as ■1 changes, ■ changes from logarithmic compression to a linear range. If the output of the circuit is vo, then R5 is the resistance value of the resistor 5, and R6 is the resistance value of the resistor 6. Therefore, the sensitivity curve of this compression circuit can be easily changed by changing the resistance values of resistor 1 and resistor 4. The curve is shown in FIG. Furthermore, although there is a temperature term due to T in the logarithmic term, it is easy to compensate for temperature changes by inserting the resistor 4 in series.

If the current decreases by ■D-dVD, then d is lower than the diode current.
(■, -vD)/(R1+R2)+/jvD/(R1+
R4) = I p + Δ, and when the forward voltage of the diode decreases due to temperature change, the current increases by Δ, and due to resistor 4 ■s becomes d
It tries to increase by R4, and as a result, due to temperature ■8
It works to compensate for changes in

A second embodiment is shown in FIG. 1 to 7 have the same configuration as the first embodiment, and the output of amplifier 7 is connected to transistor 8.
The output is outputted from the emitter of the aforementioned transistor 8, negative feedback is applied to the amplifier 7 via the resistors 5 and 6, and the output detected by the transistor 8 is smoothed by the capacitor 9 and then transferred to the resistor. 10,15...
...The voltages divided by no are compared with the reference voltage 11 and the comparator 12, 16°..., and the light emitting diode 1
4.18. The display circuit is constructed by lighting up the resistors 10, 15, .・・・
...If n has already been determined, such as in an IC, by placing the compression circuit of the present invention in front as shown in FIG. 4, it becomes possible to change the comparative voltage curve extremely easily, Accordingly, temperature compensation of the diode 2.3 can be easily performed.

Effects of the Invention The present invention can easily vary the input sensitivity curve by providing a voltage-dividing compression circuit consisting of diodes connected in parallel with each other in both directions in series with a resistor, and a resistor further connected in series. Moreover, the effect that the temperature compensation of the diode can be realized extremely easily can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional example, FIG. 2 is a circuit diagram showing an embodiment of the present invention, FIG. 3 is a diagram showing an input sensitivity curve, and FIG.
The figure is a circuit diagram showing a second embodiment. 1.5, 6.8... Resistance, 3, 4...
Diode, 7...Amplifier, A...Input terminal, B...Output terminal・Name of agent: Patent attorney Toshio Nakao and 1 other person No.1
Figure 4 Figure 2 Figure 3

Claims (1)

[Claims] One end of a first resistor is connected to the input terminal, the cathode of the first diode, the anode of the second diode, and the positive phase input side of the amplifier are connected to the other end of the first resistor, and the first diode and a cathode of a second diode are connected to one end of a second resistor, the other end of the second resistor is connected to ground, and one end of a third resistor and a fourth resistor are connected to the inverting input side of the amplifier. A signal compression circuit device, characterized in that one end of the third resistor is connected to the ground, the other end of the third resistor is connected to ground, and the other end of the fourth resistor is connected to the output side of an amplifier.