CMOS microwave multiphase voltage controlled oscillator

Abstract

A microwave differential amplifier comprises a first and a second matched NMOS device, each connected with the source to a common bias node, the gate to an input port for receiving a differential input signal and with the drains to an output port for providing a differential output signal. The Miller capacitors of each device provide the necessary feedback between the input and output ports for shifting the phase of the differential output signal with respect to the phase of the differential input signal with 45.degree. at a predetermined frequency. The operating point of the NMOS devices is maintained in the linear region of the respective transfer characteristic, using matched loads and a corresponding bias current. The loads may be resistors, in which case AGC is used for maintaining a constant bias current, or active loads. A VCO built with four such differential amplifiers in a gyrator configuration oscillates at the predetermined frequency and has eight output signals. The VCO may be used in circuits providing multiphase data regeneration where the number of data transitions exceeds the number of clock transitions in a given time period.

Dependencies are inferred from the claim text.