JPS5817209Y2 - signal selection circuit - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a signal selection circuit that extracts the maximum value or minimum value of several input signals □.

Conventionally, a maximum value selection circuit and a minimum value selection circuit made of diodes or the like have been used as signal selection circuits to select the maximum value or minimum value from among several input signals.

That is, in FIG. 1A, there are several input signals ei1. e
Diodes D1, . . ., D1 are connected to i2...ein'.
A maximum value selection circuit is shown in which □...Din is connected, each output is received by a common line 1, and one end thereof is biased with ground or a negative potential -■ through a resistor R.

In other words, when a certain input signal is at its maximum value, only the diode at that point is turned on, producing the output signal e.

This on-voltage reverse biases and cuts off the diodes to which other input signals are connected.

In addition, input signals e 11 , e12 . . . are input to the opening of FIG.
...Diode D20 to ein. D2□・・・・・・
A minimum selection circuit is shown with D2o connected in the opposite direction, receiving each output on a common line l, and biased through a resistor R with a positive potential ■.

In this case, only the diode to which the minimum input signal is connected is turned on and an output signal can be taken out, and the other diodes are cut off.

Note that all diodes may be replaced with idealized diodes consisting of an operational amplifier and a diode.

Conventional maximum value selection circuits and minimum value selection circuits operate separately, as shown in Figure 3.2. This had the disadvantage of increasing costs; and if only one of the maximum value selector or minimum value selector was prepared, the operation of the other became necessary. In this case, the circuit had to be changed, which was very inconvenient.

゛ □: What purpose of the invention? (:Ma, It was made in view of the above points, and it is possible to obtain both the maximum value and the minimum value with an extremely simple circuit consisting of an idealized diode circuit and a switch means. An object of the present invention is to provide a signal selection circuit that enables the following.

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 terminals to which input signals elte2 are supplied, respectively, and 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.

Further, the cathodes of the diodes D1 and D2 are commonly connected to a first common line 1111C, and one end thereof is grounded via a resistor R.

Also, the second common line 12 and each operational amplifier OF1°O1
Switching means FET1°FET2 consisting of an MO8 field effect transistor or the like is connected between the input terminals 1 and 2 of each operational amplifier OP1°O12, and the output terminal of each operational amplifier OP1°O12 is connected to each FET1. Each operational amplifier op, connected to and added to the gate of FET2.

FET1. FET2 is adapted to be driven.

Each common line 11, 12 is connected to, for example, a switching contact S1. Each common line 1 connected to S2
Signals 1 and 12 are optionally common contact S.

The signal is amplified and reduced by an amplifier A, and taken out from an output terminal 3.

Next, the operation will be explained assuming e, < 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 10.
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 e 1 < e 2, the output of operational amplifier OP1 is a dog at a negative potential, and this negative potential is F
is applied to the gate of ET1, so that FET1 is turned on, which means that the input signal e1 can be tapped through the FET to the second common line 12.

At this time, since the voltages applied to both input terminals of the operational amplifier 012 are at the same potential e2, the output thereof becomes zero, and the FET2 is turned off.

Similarly, in the case of e 1 > e 2, the larger signal e1 is connected to the first signal line 11, and the smaller signal e2
can be taken out to the second signal line 12.

The maximum value signal and minimum value signal extracted in this way can be transferred to the contact S by switching the changeover switch SW.
1. Common contact S via S2.

A more necessary signal can be taken out, amplified by an amplifier A, and taken out from an output terminal 3.

Note that there is no particular need to provide the changeover switch SW1 amplifier A, and two terminals may be provided to take out the maximum value signal and the minimum value signal.

Furthermore, as another embodiment of this invention, if the direction of the diode is reversed and the first common line 11 is biased with a positive potential through a resistor, the first common line 11
The minimum value can be taken out from , and the maximum value can be taken out from the second common line 12 .

As explained in detail above, this invention is a maximum value/minimum value signal selection circuit that includes an idealized diode circuit consisting of an operational amplifier and a diode, and two switch means driven by the output of this operational amplifier. be.

Therefore, we took the trouble to create two maximum value selection circuits and two maximum value selection circuits.
Even without preparing a circuit, both the maximum value and minimum value signals can be obtained by simply preparing one simple circuit such as adding a switch means such as an FET.

Furthermore, since an idealized diode circuit is used, the operation is extremely reliable, and various application examples are possible.

Such a signal selection circuit is useful when you want to select and extract either the maximum value or the minimum value of temperature signals at two points in a greenhouse, etc., or when you want to select and extract the humidity signal and temperature signal at two points in the air conditioning control of a room. It can be used in cases where the minimum signal or maximum signal is always selected and used to drive and control one operating end.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram showing one embodiment of a conventional signal selection circuit, and FIG. 2 is a connection diagram showing one embodiment of this invention. 1.2...Input terminal, 3...Output terminal, OPl. O12...Operation amplifier, Dl, D2...
・Diode, FET1. FET2... Switch means, 11, 12... Common line.

Claims (1)

[Scope of utility model registration request] An operational amplifier to which an input signal is supplied to the input terminal, and a diode connected to the output terminal of this operational amplifier to provide negative feedback, are two sets of idealized diode circuits, and the output side of each idealized diode circuit is common. The first common line is connected between the input terminals of each idealized diode circuit and the second common line. 1. A signal selection circuit comprising a switch means provided for each idealization diode circuit that can be turned on, and extracting the maximum value or minimum value of an input signal from each of the common lines.