发明授权
- 专利标题: Digital and analog phase detector for a frequency synthesizer
- 专利标题(中): 用于频率合成器的数字和模拟相位检测器
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申请号: US251570申请日: 1981-04-06
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公开(公告)号: US4490688A公开(公告)日: 1984-12-25
- 发明人: Jaime A. Borras , Jose I. Suarez , Alan M. Victor
- 申请人: Jaime A. Borras , Jose I. Suarez , Alan M. Victor
- 申请人地址: IL Schaumburg
- 专利权人: Motorola, Inc.
- 当前专利权人: Motorola, Inc.
- 当前专利权人地址: IL Schaumburg
- 主分类号: H03C3/09
- IPC分类号: H03C3/09 ; H03C3/22 ; H03D13/00 ; H03J5/02 ; H03K23/66 ; H03L7/08 ; H03L7/193 ; H03L7/199 ; H04B1/40 ; H03L7/12
摘要:
A sample and hold phase detector for a phase locked loop includes a digital detector for detecting the frequency and phase difference between the reference signal and the voltage controlled oscillator (VCO) signal. In a first mode of operation, the digital detector generates a first signal relating the difference in frequency and in a second mode of operation generates a second signal relating the difference in phase. A capacitor stores the first or second signal depending on the operational mode of the digital detector. The capacitor is selectively discharged in response to a discharge signal produced by the digital detector when either the VCO frequency is higher than the reference frequency or following each detection of a phase difference. A first amplifier is used to bypass a portion of the loop filter to effect rapid changes in VCO frequency in the first mode while a second amplifier couples the control voltage to the VCO via the loop filter to maintain proper VCO frequency in the second mode.
公开/授权文献
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