Integrated circuit tuner for HF superheterodyne receiver - derives sampling signal for phase=locked=loop from common VHF-UHF amplifier output connection within IC

摘要

The IC tuner converts HF signals, from VHF or UHF band, to IF signals. A phase-locked loop sampling signal is taken from the output of a VHF amplifier (7) or UHF amplifier (11) instead of directly from a resonant circuit, and is amplified (20) before being applied to a PLL circuit (18) via a balanced-to-unbalanced convertor (22). This arrangement eliminates the VHF PLL amplifier conventionally used between the VHF resonant circuit (16) and the PLL circuit, and safeguards stability of the resonance. USE/ADVANTAGE - In VHF or UHF band, PLL amplifier can be eliminated from peripheral circuits without detriment to oscillation stability.