发明名称 |
Low noise reference oscillator with fast start-up |
摘要 |
A frequency source having a fast start-up time and low noise in steady state is presented. The frequency source includes an oscillator and a hybrid automatic gain control (AGC) loop that switches between an analog AGC loop at oscillator start up and a digital AGC loop at steady state operation. The analog AGC loop includes a peak detector connected to the oscillator and an error integrator integrating the difference between the peak detector output and a reference voltage. The digital AGC loop includes a comparator comparing the peak detector output and high/low reference voltages, an oscillator counter providing a timer signal, a digital-to-analog converter (DAC) supplied with a digital word, and a low pass filter between the DAC and the oscillator. The timer signal causes a multiplexer to select either the analog AGC loop or the digital AGC loop.
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申请公布号 |
US7332979(B2) |
申请公布日期 |
2008.02.19 |
申请号 |
US20050261978 |
申请日期 |
2005.10.28 |
申请人 |
FREESCALE SEMICONDUCTOR, INC. |
发明人 |
CONNELL LAWRENCE E.;MCCARTHY DANIEL P.;BUSHMAN MICHAEL L. |
分类号 |
H03B5/36 |
主分类号 |
H03B5/36 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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