Oscillator circuit with signal buffering and start

专利名称：Oscillator circuit with signal buffering and

start-up circuitry

发明人：Tom C. Truong申请号：US09832686申请日：20010410公开号：US06445258B1公开日：20020903

专利附图：

摘要：A crystal oscillator circuit includes a crystal driven by a variable current sourcehaving a transconductance device with transconductance dependent on current, and aCMOS buffer circuit for receiving a sinusoidal signal from the crystal and providing a

square wave output signal. The buffer circuit includes first and second bi-level bufferscapacitively coupled to receive sinusoidal signals and operating in a push-pull mode forproviding square wave output signals from each of said first and second buffers, and athird buffer driven by output signals from the first and second buffers, whereby dutycycle of the first and second buffers is controlled by bias voltages applied to CMOStransistors in the buffers. The circuit further includes a bias current circuit which providesthrough the variable current source a bias current, I-bias, which is set to provide anoptimum transconductance for oscillation start-up and a reduced regulated bias currentonce oscillation voltage increases, thereby preventing runaway oscillations.

申请人：ZEEVO, INC.

代理机构：Townsend and Townsend and Crew LLP

代理人：Henry K. Woodward

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