Telecommunications – Receiver or analog modulated signal frequency converter – Noise or interference elimination
Reexamination Certificate
2007-12-11
2007-12-11
Vuong, Quochien B. (Department: 2618)
Telecommunications
Receiver or analog modulated signal frequency converter
Noise or interference elimination
C455S339000, C333S167000, C327S557000
Reexamination Certificate
active
11488768
ABSTRACT:
A conventional receiver system has a filter circuit with unsatisfactory gain characteristics, and thus does not offer satisfactory reception performance. A receiver system of the invention has a filter circuit employing an equivalent inductor circuit including a capacitor, a gyrator composed of a plurality of operational transconductance amplifiers and having the capacitor as a load, and a resistor connected in series with the capacitor. A conventional receiver system has a band-pass filter circuit with a low third-order input intercept point, and thus does not offer satisfactory reception performance. The receiver system of the invention has, in the stage following a mixer, a band-pass filter circuit composed of a low-pass filter and a band-pass filter receiving the output signal of the low-pass filter, wherein the value obtained by dividing the higher cutoff frequency of the band-pass filter by the lower cutoff frequency thereof is smaller than 2, the center frequency of the band-pass filter is within a range of from about 1 to 3 MHz, and the cutoff frequency of the low-pass filter is higher than the center frequency of the band-pass filter.
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Ashida Hiroyuki
Shimada Yoshikazu
Morgan Lewis & Bockius
Rohm & Co., Ltd.
Vuong Quochien B.
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