| 摘要 |
PURPOSE:To control an oscillation frequency in proportion to a control signal by forming a loop of a variable phase shifter, band-pass filter (BPF) and amplifier. CONSTITUTION:Output SA of amplifier 30 is inputted to variable phase shifter 40, whose output SC is inputted to BPF10, output SD of which is fed back to amplifier 30, obtaining a stable oscillator. Amplification characteristics of BPF are shown by curve La, and phase characteristics by curve LD. Then, it oscillates in frequency band W where gain G is >=1. Since output phase phiOUT to control current IY is shown by curve Lc, control signal Ix is applied to phase shifter 40 via linear corrector 50 to vary its oscillation frequency in proportion to the control signal. Thus, this can be used as a time axis correcting circuit for color signals used for VTR, etc. |
