A Single-ECL/12L-Chip PLL IC for Frequency Synthesized TV Tuning System

A microcomputer-controlled PLL bipolar IC including prescalers,has been developed. The ECL circuit contains a wideband band buffer amplifier and a high speed (1.2 GHz) prescaler. The I2L circuit contains all the PLL logic functions. A novel digitally-controlled frequency offset circuit using a 3 modulo prescaler and a rate multiplier, was designed in order to detune the local oscillator frequency from the center in the ±2MHz (±1 MHz) range with 31.25KHz(15.625KHz) steps. It makes this IC applicable to any nation's TV channel frequency. A new IC technology realizes both a high fT (4GHz) linear transistor and a high speed I2L gate (tpd=7n sec for a single collector) on the same chip.