发明公开
EP0455038A2 Advance/retard control circuit with PDM accumulator and second order loopfilter
失效
与PDM存储和二阶环路滤波器馈送/减速控制装置。
- 专利标题: Advance/retard control circuit with PDM accumulator and second order loopfilter
- 专利标题(中): 与PDM存储和二阶环路滤波器馈送/减速控制装置。
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申请号: EP91106008.5申请日: 1991-04-16
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公开(公告)号: EP0455038A2公开(公告)日: 1991-11-06
- 发明人: Wong, Hee , Wilson, Howard , Guinea, Jesus
- 申请人: NATIONAL SEMICONDUCTOR CORPORATION
- 申请人地址: 2900 Semiconductor Drive P.O. Box 58090 Santa Clara California 95051-8090 US
- 专利权人: NATIONAL SEMICONDUCTOR CORPORATION
- 当前专利权人: NATIONAL SEMICONDUCTOR CORPORATION
- 当前专利权人地址: 2900 Semiconductor Drive P.O. Box 58090 Santa Clara California 95051-8090 US
- 代理机构: Sparing Röhl Henseler Patentanwälte
- 优先权: US518029 19900502
- 主分类号: H04L7/033
- IPC分类号: H04L7/033 ; H04L25/48
摘要:
A digital loop filter translates a multi-bit phase error input into a high resolution control signal utilizable as an advance-retard control for a multi-phase clock generator. The digital filter couples the multi-bit phase error input to the clock generator via a pulse density modulation (PDM) accumulator, providing multi-phase adjustment in a single sample clock cycle based on the overflow or underflow of the PDM accumulator. Variable PDM cycles are used to control loop filter bandwidth, permitting adjustable capture sequences. Thus, real proportional control of the multi-phase clock generator is limited only by the word size of the phase error input.
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