Transistor-only low-voltage RF quadrature oscillator and frequency divider

An inductorless oscillator operating in the current domain for generating radio-frequency quadrature signals is presented. The quadrature phase and gain requirements can be achieved by cascading four low-voltage regulated cascode cells in a ring fashion. To demonstrate the proposed topology, a 0.9-V oscillator working from 0.44 GHz to 3.4 GHz and having a phase noise variation ranging between -92 dBc/Hz to -84.6 dBc/Hz at 3-MHz offset was simulated for a 0.18-μm standard digital CMOS technology. In addition to working as a quadrature oscillator, the proposed circuit can be utilized as a frequency divider without modifying the topology.