A TV-PLL-circuit for automatic tuner alignment

Modern highly integrated TV systems are MCU controlled (12C-bus) and replace mechanical adjustment by electronic alignment. The integrated circuit described has been developed for such a system. The IC contains all PLL functions that are required to control a TV local oscillator and also includes a D to A converter section that generates three further varicap voltages for optimum control of the tuner filters. The unique feature of the IC is that it generates the four varactor control voltages on chip in a range of up to 30 V and that it also contains the PLL functions that require high frequency operation (1.3 GHz).<>