SU1406767A1 - Analog gate - Google Patents

Description

(21) 4155131 / 2A-2I

(22) 03.12.86

(46) 06.30.88. Bü 24

(72) A.S. Korabelnik, N.O. Korabelnik and V; V.Halturin

(53) 621.382 (088.8)

(56) U.S. Patent 3,509,374, Cl. 307-239, 01.05.67.

USSR Author's Certificate No. 586566, cl. And 03 K 17/60, 06.06.75.

(54) ANALOG KEY

(57) The invention can be used for switching high-voltage

dual analog signals in communication systems. The purpose of the invention is to expand the range of switched signals. The analog switch contains MOS transistors (t) 1 and 2, diode 6 and resistors 8 and 9. Introduction of MDP-T 3, zener diodes 4 and 5, and diode 7 provides control of the key T using the switching signal itself, using a low-voltage control signal, necessary only for unlocking SCHSCH-T 3, included in the scheme with a common source. 1 il.

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The invention relates to a pulsed technique and can be used for switching high-voltage bi-polar analog signals in communication systems, monitoring and measurement.

The aim of the invention is to expand the range of switched signals by introducing into the bipolar analog key two Zener diodes, a diode and an additional MIS transistor, thereby allowing the key transistors to be controlled by the switching signal itself using the low-voltage control signal required for unlocking the additional signal MOSFET connected according to the common source circuit.

The drawing is a schematic diagram of an analog key,

The device contains the first 1, second 2 and third 3 MDI transistors, two Zener diodes A and 5, two diodes 6 and 7 and two resistors 8 and 9, Input buses 10 and 11 of the device are connected to the cathodes of diodes 6 and 7, respectively, and anodes of zener diodes A and 5, the sources and substrates of MOS transistors 1 and 2, the drain of the first 1 and second 2 MOS transistors are connected respectively to the output buses 12 and 13, the cathodes of the Zener diodes 4 and 5 are connected to the gates of the first and second MOS transistors and with the first pins of resistors 8 and 9, the second pins of which are combined and connected cheny to the drain of the third MISFET 3, the source and the substrate on which edin us and connected to the anodes of diodes 5 and 7 and to the first control terminal 14 and whose gate is connected to the second control terminal 15.

The analog key works as follows.

A two-pole signal is applied to the output buses 10 and 11. For example, bus 10 has a positive switching voltage pole. At the same time, the first Zener diode 4 is open in the forward direction, and the first MIS-transistor of 1 n-type is open across the substrate, since its p - –P junction substrate – drain is shifted in the forward direction. If the potentials of the first 14 and second 15 control terminals are the same, then the third MOS transistor 3 is closed. At the same time, the positive potential from the first input PX1-1Y 10 is supplied for

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the thief of the second MOS transistor 2 and opens it. The control voltage of the gate - the source of this transistor is equal to the switched voltage. But it cannot exceed the breakdown voltage of the zener diode 5. This mode corresponds to the open state of the analog switch when the switching voltage from the input buses 10 and 11 is transmitted to the output buses I2 and 13 and in the load

In the closed state of the key, it is sufficient to apply a positive voltage to the second control terminal 15 with respect to the first control terminal 14, above the threshold voltage of the MOS transistor. The third MOS transistor 3 opens and shunts the second diode 7 and the second Zener diode in series due to the fact that the second diode 7 is open in the forward direction. As a result, the gate voltage - the source of the second MOS transistor 2 is small and not enough to unlock this transistor. The second MOS transistor 2 open prevents the switching signal from passing through the input buses 10 and 11 to the output buses 12 and 13 and into the load. The analog key is closed,

As MDP transistors, it is advisable to use DMDP transistors having a higher permissible operating voltage.

The use of the proposed analog switch allows the use of a low voltage control signal for switching high voltage analog signals by limiting their level only by the breakdown voltage of the zener diodes and the operating voltages of the used MOS transistors,

The proposed analog key is advisable to use in automatic telephone dialing telephone devices with power from the central PBX battery,

Claims (1)

Invention Formula An analog switch containing the first and second MOS transistors, a diode and two resistors that are connected in series, the sources of the MOS transistors connected to the corresponding) and input buses, and the drains from the output buses 1 and 2, characterized in that expanding the range of switching voltages, a third MOSFET, a second diode and two Zener diodes are inserted into the analog switch, the anodes of the Zener diodes are connected to the sources of the first and second MOSFET cooTBeTcfBeHHo, and the cathodes are connected to the same MIS transistors with free pins of resistors, JQ combined. the common point of which is connected to the drain of the third MOS transistor, the source of which is connected to the anodes of the diodes and the first control terminal, and the gate to the second control terminal, the cathodes of the diodes are connected to the corresponding input buses, and the source and substrate of each MIS transistor