Phase control circuit suitable for use in a tint control stage of a

Abstract

A controllable phase shifting circuit suitable for providing tint control in a color television system comprises first and second differential amplifiers, each providing antiphase outputs and supplied respectively with first and second alternating color reference signals which are in a first predetermined (e.g., quadrature) phase relation. A third signal, which is a fractional part of one of the first two signals, is combined with the other of the first two signals at its respective amplifier input to produce a fourth signal with a phase different from that of the first, second or third signals. A third amplifier provides differential gain control inputs to the first and second amplifiers. A combining circuit sums relatively in-phase or antiphase output signal components from the first and second amplifiers to produce an output signal with a desired phase (e.g., flesh tone phase). The desired phase is controllable in accordance with the gain control input signals such as can be developed in response to an adjustable tint control potentiometer or similar device.