JPS5918519Y2 - absolute value circuit - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an absolute value circuit that obtains the absolute value of the difference between two signals.

Conventionally, in this type of circuit, as shown in FIG. 1, input signals e1 . A subtraction circuit 3 takes a difference between e2 and a rectifying amplifier 4, which outputs a positive signal regardless of whether the output of the subtraction circuit 3 is positive or negative, and input signals e1. Output the absolute value of e2 -el-e2- to terminal 5
I was trying to get more.

However, in such a circuit, in addition to the subtraction circuit,
A rectifying amplifier with good performance is always required, and creating this rectifying amplifier requires a large number of parts, which inevitably results in a complicated and expensive circuit, and it is difficult to obtain an absolute value signal with high precision. It was.

The purpose of this idea was made in view of the above points.
To provide an absolute value circuit capable of obtaining the absolute value of the difference between two human input signals with high precision using an extremely simple circuit configuration in which an idealized diode circuit, a switch means, and a subtraction circuit are combined.

This invention will be explained below with reference to the drawings.

FIG. 2 is a connection diagram showing an embodiment of this invention.

In the figure, 1 and 2 are input signals e1. e2 are supplied to the respective operational amplifiers OP1. OP
2 non-inverting input terminal.

And each operational amplifier OP1. The output terminal of OP2 is connected to the diode D1. D2 is connected to the anode side of each diode D1. The cathode side of D2 is connected to an operational amplifier OP1. Negative feedback is applied by connecting it to the inverting input terminal of OP2, forming a so-called idealized diode circuit.

Furthermore, each diode D1. The cathode sides of D2 are commonly connected to the first common line 11, and one end thereof is grounded via a resistor R.

Also, the second common line 12 and each operational amplifier OP1°O1
Between the input terminals 1.2 of 2, switch means FET1.2 consisting of an MO3 field effect transistor or the like is connected. FET2 is connected to each operational amplifier OP1. The output terminal of OP2 is connected to each FET1. Each operational amplifier OP1. The output signal of OP2 causes FET1. FET2 is adapted to be driven.

The common lines 1□ and 1□ are respectively connected to the positive and negative input terminals of the subtraction circuit 3, and the output of the subtraction circuit 3 is taken out from the output terminal 5.

Next, the operation of the absolute value circuit of this invention constructed in this way will be explained.

(1) When el<e2 In this case, the diode D2 is turned on via the operational amplifier OP2, and this on-voltage e2 is applied to the first signal line 11.
can be taken out.

This voltage e2 reverse biases the diode D1 to cut it off and is applied to the inverting input terminal of the operational amplifier OP1.

Here, since el<e2, the output of the operational amplifier OP1 is large at negative potential, and this negative potential is applied to the gate of FET1, which turns on FET1, that is, the human input signal e1 passes through FET1 to the second common line. 1
It can be taken out in 2.

At this time, since the voltage applied to both input terminals of the operational amplifier 022 is in the identification state e2, its output becomes zero, and the FET2 is turned off.

In this way, the larger input signal e2 is taken out to the first common line 11, and the smaller input signal e1 is taken out to the second common line 12.

Both signals e2. Since e1 is added to the positive and negative input terminals of the subtraction circuit 3, the result of subtraction is e2−el
is output and can be taken out from the output terminal 5.

(2) Case where el>e2 In this case, in exactly the same way as described above, the diode D1 is turned on, the larger input signal e1 is taken out to the first common line 11, and the larger input signal e1 is output to the second common line 1□. can extract the smaller input signal e2.

Both signals e1. Since e2 is added to the positive and negative input terminals of the subtraction circuit 3, the result of subtraction is el-e2
is output and can be taken out from the output terminal 5.

In other words, considering cases (1) and (2) together,
If the input is e1 < e2, the output is e2-e1 human power is el
> e2, the output is el-e2, that is, the output signal is the input signal e1. Absolute value of difference in e2 - el - e2
- corresponds to -.

In another embodiment of this invention, the direction of the diode is reversed and the first common line 11 is biased through a resistor, so that the first common line receives the smaller input signal, the first common line. Since the larger input signal can be extracted from the two common lines 12, if the signals on these common lines 11 and 12 are subtracted by a subtraction circuit, an absolute value signal can be obtained in the same way.

Note that by reversing the input polarity of the subtraction circuit, a negative absolute value signal can always be obtained.

Further, by providing an output terminal on both common lines, it is possible to extract not only the absolute value signal but also the maximum value signal and the minimum value signal.

As detailed above, this invention consists of two idealized diode circuits and a maximum
This is an absolute value circuit that obtains the absolute value signal of the difference between two human input signals by subtracting the minimum signal.

Therefore, since the number of parts is extremely small, it is inexpensive and reliability is improved, and since there are few error factors, it is possible to obtain an absolute value signal with high precision.

In addition, since the maximum value signal and minimum value signal can be taken out at any time as needed, it is possible to obtain three types of signals, the absolute value, maximum value, and minimum value, with the -circuit, which is very convenient. be.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram showing a conventional example of an absolute value circuit, and FIG. 2 is a connection diagram showing an embodiment of this invention.

Claims (1)

[Claims for Utility Model Registration] 1. An operational amplifier to which an input signal is supplied to its input terminal, two idealized diode circuits in which a diode is connected to the output terminal of this operational amplifier to provide negative feedback, and each A first common line that commonly connects the output sides of the idealized diode circuits, and a second common line that connects the input terminals of each idealized diode circuit in common.
a switch means provided in each idealized diode circuit connected between the first common line and driven on when each diode is cut off by the output of each operational amplifier; providing the larger output signal to the positive input terminal; providing the smaller output signal of the second common line to the positive input terminal; and providing the smaller output signal of the second common line to the negative input terminal. and a subtraction circuit for subtracting both signals. 2. The absolute value circuit according to claim 1, wherein the absolute value circuit is configured to take out the maximum value signal from the first common line and take out the minimum value signal from the second common line.