QUALCOMM Incorporated
System and method for maintaining local oscillator (LO) phase continuity

Abstract:

A local oscillator (LO) circuit includes a voltage controlled oscillator (VCO) configured to receive an output of a phase locked loop (PLL) circuit, the VCO coupled to a clock gating circuit configured to generate a VCO output signal (vco_g), a local oscillator (LO) divider configured to receive the VCO output signal (vco_g) and a local oscillator (LO) preset signal, the LO preset signal configured to set the LO divider to a predetermined initial phase, a programmable divider configured to receive a divider signal and the VCO output signal (vco_g) and generate a local oscillator (LO) phase detection trigger signal, Fv, a toggling accumulator coupled to an output of the programmable divider, the toggling accumulator configured to receive the divider signal and the LO phase detection trigger signal, Fv, and generate a counter signal, and a decision logic configured to receive a sample enable signal and the counter signal and adjust the programmable divider based on the sample enable signal and the counter signal.