Electronic switch circuit

Abstract

Abstract PURPOSE:To make it possible to pick up an output current which is equal to the input current irrespective of the voltage level of input signal when input and output terminals are shorted, by setting the control electrode currents of 2 pieces of active elements connected between input and output terminals of the same value. CONSTITUTION:Each emitter of NPN transistor TRQ1 and PNP transistor TRQ2 is connected to input terminal 1 after they are commonly connected to each other, and each collector of the transistors is commonly connected to each other and then connected to output terminal 2. Bases of TRQ3 and Q4 are connected to control terminal 3'. Since characteristics of TRQ3 and Q4 are the same, and collector current I5 of TRQ4, current I6 flowing through diode D5 inserted between power source 5 and TRQ4, collector current I2 of TRQ3, and collector current I1' of TRQ5 become almost the same, the following equation is realized; I5=I6=I1'=I2'. By this, current I1' and I2' will not be changed in accordance with the voltage level of input signal, and then output current I4 which is equal to input current I3 can be picked up.

Inventors

• 👤 Tomoaki Uchida

Bibliographic Details