发明授权
- 专利标题: Frequency calibration standard using a wide band phase modulator
- 专利标题(中): 使用宽带相位调制器的频率校准标准
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申请号: US424454申请日: 1989-10-20
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公开(公告)号: US5101506A公开(公告)日: 1992-03-31
- 发明人: Fred L. Walls
- 申请人: Fred L. Walls
- 申请人地址: DC Washington
- 专利权人: United States of America, As Represented By The Secretary Of Commerce
- 当前专利权人: United States of America, As Represented By The Secretary Of Commerce
- 当前专利权人地址: DC Washington
- 主分类号: G01R29/26
- IPC分类号: G01R29/26 ; H03C3/40
摘要:
A phase modulator for use in a two-oscillator phase noise measurement sys is placed in the line from either the reference oscillator or the device under test. The phase modulator couples a small portion of the input signal to an amplitude modulator and phase shifter to shift the small signal by exactly 90 degrees. The small signal portion is then coupled back into the input signal such that small variations in the coupled signal result in phase modulation and not amplitude modulation which would undermine the calibration of the instrument. The phase modulator described can also be used with known devices of many types to correct the added phase noise of components, e.g., power amplifiers. The phase modulator, when used with a given fixed or variable frequency source, also forms a frequency calibration standard in a single portable instrument.