IMPEDANCE CONVERTING CIRCUIT

摘要

PURPOSE:To attain fcree direct-couling with an amplifier stage and an electronic circuit realized in an IC by coupling an emitter follower circuit and a serial/ parallel feedback circuit to set freely the output impedance and increase the input impedance. CONSTITUTION:An output of a stage 10 consisting of a transistor (TR) Q1 and resistors R1-R4 and having an ordinary gain is fed to an input terminal 11 of an impedance converting circuit 9. The circuit 9 consists of an emitter follower level shift circuit and a serial/parallel feedback amplifier circuit and the output of the emitter follower level shift circuit is connected to the input of the serial parallel feedback circuit. Furthermore, the emitter follower level shift circuit is constituted by connecting a TRQ2, a level shift circuit 8 and resistors R5, R6 as shown in the figure and the serial parallel amplifier circuit is constituted by connecting a TRQ3 and resistors R7-R9 as shown in Fig.