Demodulators – Frequency modulation demodulator – Having specific distortion – noise or other interference...
Reexamination Certificate
2005-12-20
2005-12-20
Mis, David (Department: 2817)
Demodulators
Frequency modulation demodulator
Having specific distortion, noise or other interference...
C329S300000, C329S319000, C375S322000, C455S205000, C455S268000, C455S334000, C455S339000, C455S340000, C455S341000
Reexamination Certificate
active
06977545
ABSTRACT:
An FM signal receiver for use in receiving a burst signals as in a Bluetooth system includes a BPF and a frequency-demodulation circuit, each having, for example, a phase shifter, which is constructed from similar or related circuitry so as to enable adjustment of the frequency characteristics of the BPF and frequency-demodulation circuit through an identical control signal. A short-circuit switch is disposed linking the input and output terminals of an amplifier. A control circuit opens the switch in a receiving operation and closes the switch in an adjusting operation. Thus, adjustment is carried out without using the amplifier. Therefore, an amplifier offset does not affect the frequency-to-voltage conversion by the frequency-demodulation circuit in the adjusting of the frequency-demodulation circuit and similar adjusting of the BPF. Thus, the BPF is prevented from being incorrectly adjusted due to the offset. The BPF characteristics are suitably adjusted.
REFERENCES:
patent: 6188275 (2001-02-01), Mattisson et al.
patent: 6850113 (2005-02-01), Amano
patent: 2002/0135418 (2002-09-01), Amano
patent: 7-115328 (1995-05-01), None
Amano Shinji
Kishino Yusuke
Birch & Stewart Kolasch & Birch, LLP
Mis David
Sharp Kabushiki Kaisha
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