A CMOS VCXO for FM Stereo Decoders

The design and implementation of a CMOS voltage-controlled crystal oscillator is described. A novel circuit technique is presented for the tuning of crystal oscillation frequencies. Apart from the novel feature of the tuning circuit, the resonator is grounded in the oscillator, so that only one pin is required for the resonator. This can be very important for certain applications where the total package pin count must be minimized. The prototype of the VCXO has been fabricated in a 4-jim standard CMOS process. Experimental results will be presented.