High-frequency MOS digital capacitor

A MOS digital capacitor capable of operation at VHF and UHF frequencies is described. This new device is made up of a parallel combination of MOS capacitors each of which can be individually switched between two distinct capacitance values; a maximum binary state being the high-frequency MOS inversion capacity and the minimum being that of a deep-depletion MOS device, Switching is accomplished by on chip MOSFET's. Isolation of the RF terminals is accomplished by the high intervening channel impedances of the switching MOS gates. The basic structure and the principles of operation will be discussed, and operational performance figures for RF tuning range, linearity, dynamic range, and figure of merit Q will be presented.