发明名称 |
Phase-shifting multiplication type FM signal demodulation circuit |
摘要 |
A phase-shifting multiplication type FM demodulation circuits comprises a gate circuit including a first and a second switching circuit adapted to be switched for an FM intermediate frequency signal, a resonance circuit and a phase-shifting element. The FM intermediate frequency signal is phase-shifted for about pi /2 (or 90 DEG ) and the phase-shifted signal (frequency) is fed to the second switching circuit of the gate circuit after the phase-conversion of the phase-shifted FM signal by means of a phase-shifter device. The demodulation circuit further includes a bias resistor for the second switching circuit which resistor serves also as a resonance resistor of the resonance circuit, a substraction circuit for detecting output signal from the gate circuit, an output resistor for determining magnitude of the output signal from the subtraction circuit, and a lowpass filter for eliminating higher harmonics from the output signal appearing across the output resistor thereby producing a demodulated output.
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申请公布号 |
US4122394(A) |
申请公布日期 |
1978.10.24 |
申请号 |
US19770759444 |
申请日期 |
1977.01.14 |
申请人 |
HITACHI, LTD. |
发明人 |
FUKUSHIMA, ISAO;ISO, YOSHIMI;AKITAKE, ISAO |
分类号 |
H03D3/18;(IPC1-7):H04B1/16 |
主分类号 |
H03D3/18 |
代理机构 |
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主权项 |
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地址 |
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