A Process and Temperature Compensated Two-Stage Ring Oscillator

February 20, 2009
2:00pm-3:00pm
Interschool Lab, Room 750 CEPSR
Hosted by: Prof. Yannis Tsividis
Speaker: Kumar Lakshmikumar, Conexant Systems, Inc

Abstract

Local positive feedback in a delay element enables a ring oscillator with only two stages to oscillate and produce quadrature clocks. Routh-Hurwitz’s criterion is applied to prove that such a structure can oscillate. An internally generated power supply from a constant-gm bias keeps the free running frequency to within ± 5% from -40 to 125˚C over process variations. The 1.25GHz oscillator in 0.13μm CMOS draws 3.4mA and has a phase noise of -88dBc/Hz at 1MHz offset.

Local positive feedback in a delay element enables a ring oscillator with only two stages to oscillate and produce quadrature clocks. Routh-Hurwitz’s criterion is applied to prove that such a structure can oscillate. An internally generated power supply from a constant-gm bias keeps the free running frequency to within ± 5% from -40 to 125˚C over process variations. The 1.25GHz oscillator in 0.13μm CMOS draws 3.4mA and has a phase noise of -88dBc/Hz at 1MHz offset.


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