JPS5720046A - Testing circuit of receiver - Google Patents

Abstract

PURPOSE:To decrease the man-hours of testing and to shorten a test time by excluding errors due to difference of the integrated circuit of a receiver to be tested by comparing the phase of an input signal to the receiver to be tested with that of the signal of a local oscillator and by varying the resonance frequency of the tuning circuit of the loca oscillator on the basis of the result of the comparison. CONSTITUTION:The output of a resting high-frequency signal generator 1 is supplied to an integrated circuit 2 for a radio receiver and then inputted to th reference input terminal of a phase comparator 13 via a frequency divider 12. To a terminal where the turning circuit of the local oscillator 8 of the circuit 2 is connected, a tuning circuit 16 including a variable inductance circuit is connected. Further, the controlled-signal input terminal of the comparator 13 is connected to the terminal 4 via a frequency divider 14. Then, the comparator 13 compares the output phase of the generator 1 with the oscillation signal phase of the oscillator 8 to control the variable inductance circuit of the tuning circuit 16 via an LPF15, and consequently varies the resonance frequency of the oscillator 8 to exclude errors due to difference of the integrated circuit 2.