Filter automatic equalization circuit and standard electric current generation circuit

摘要

PURPOSE: To realize an automatic filter adjustment circuit in which a filter to be adjusted is adjusted with high accuracy and to realize the reference current generating circuit in which number of both IC terminals and elements is reduced, a current proportional to the absolute dispersion is generated and realizing the circuit with high accuracy. ;CONSTITUTION: A f_sc trap requiring accuracy of f₀ in an active filter with a video signal processing IC or the like built in is formed by a so-called (1-BPF) circuit comprising a BPF 61, an arithmetic operation circuit 62 subtracting a signal v_in passing through the BPF 61 from an input signal v_in and combining the BPF 61 with the arithmetic operation circuit 62. Moreover, a reference filter 2a for a f₀ automatic adjustment circuit is made of the same BPF. Thus, almost completely stabilized f_sc trap for various dispersion factors for the f₀ is realized.;COPYRIGHT: (C)1994,JPO&Japio