| 摘要 |
PURPOSE:To form a variable impedance across both ends of a resistance region stably in response to a control input by providing Tr group of reverse conductive type to the variable impedance elements of transistor Tr group of parallel connection and operating the impedance element by utilizing the Tr group. CONSTITUTION:P-N-P type TRQP1-QPn, QP1'-QPn' of parallel connection operating as a variable impedance element are formed of P type diffused layer 4, a P type layer 5 and an N type layer 6. Correspondingly, reverse conductive type N-P-N type TrQN1-QNn, QN1'-QNn' having an N type layer 6 of collector, a P type diffused layer 7 of base and an N type layer 7 of emitter are formed. The ON operations of the P-N-P type Tr group is controlled by utilizing the Tr group, and the impedance between the contact units 1-3 is set variably in response to the control input. In this manner, stable impedance variation can be performed. |
