FREQUENCY AMPLICATION CIRCUIT

摘要

The circuit generates a clock signal to create a blue screen, and includes two serially connected frequency doublers. Each doubler includes a phase inverter (30) for inputting and phase inverting a colour subcarrier signal, and a 90 degree phase shift circuit (40) for inputting the colour subcarrier signal and performing 90 degree phase shifting. A multiplying circuit (50) outputs a doubled signal as a result of an exclusive-OR multiplication of the output of the phase inverter by the output of the 90 degree phase shifting circuit. The multiplying circuit is an analog multiplier.