AUTO-TRACK FINDING DETECTING CIRCUIT FOR 8MM VIDEO TAPE RECORDER

摘要

PURPOSE:To constitute all circuits in an integrated circuit and eliminate a need of resonance frequency adjustment by providing a band-pass filter consisting of a switched capacitor filter to which the output of an analog multiplier is connected. CONSTITUTION:The output of an analog multiplier B1 is connected to inputs of two band-pass filters F1 and F2 consisting of switched capacitor filters SCFs. An 8mm VTR video signal and a reference frequency are applied to two input terminals I1 and I2 of the analog multiplier B1, and detection outputs are obtained from output terminals O1 and O2 of two band-pass filters. Since band- pass filters of an ATF (auto-track finding) detecting circuit of the 8mm VTR consist of SCF circuits, coils for band-pass filters which hinder all circuits from being constituted into an integrated circuit are excluded and are substituted with differential amplifiers, capacitors, switches, or the like which can be mounted on the integrated circuit. If the constituting method is adopted where circuits are formed on the same integrated circuit at a time, a high precision is secured, and as the result, adjustment of the resonance frequency is unnecessary.