A fully integrated five-gyrator filter at video frequencies

An experimental single-chip silicon integrated-circuit filter is described for use in color television receivers. It comprises five gyrator resonators operating in the range 4-6 MHz. This chip provides all the selectivity required to separate the sound, luminance, and chrominance components from the composite video signal, and is tuned by a single bias potential applied to the p-n junction capacitors on the chip. The chip replaces an equivalent LC filter of about 20 discrete components (coils, capacitors, and resistors) which are bulky, are relatively expensive, and suffer from the need for individual screening and alignment. The theory of gyrators related to providing fully integrated selectivity at high frequency is outlined. Performance boundaries in terms of Q-factor, frequency setting accuracy, noise, distortion, and temperature are considered. Design aspects are discussed, first for a gyrator and then for the complete experimental filter chip.