Telecommunications – Receiver or analog modulated signal frequency converter – Local control of receiver operation
Patent
1997-03-27
2000-02-15
Nguyen, Lee
Telecommunications
Receiver or analog modulated signal frequency converter
Local control of receiver operation
4552341, 4552451, 455550, 330149, 375345, H04B 106
Patent
active
060262850
ABSTRACT:
A variable attenuator circuit provides variable attenuation responsive to received signal strength in a receiver to reduce intermodulation (IM) distortion. In a dual-mode frequency modulation/code division multiple access (FM/CDMA) cellular telephone implementation, the variable attenuator circuit decreases IM distortion by variably attenuating received radio frequency (RF) signals before an initial RF amplification stage to reduce the level of undesirable frequency mixing products. The variable attenuator circuit is turned on (activated) and off (deactivated) at a single, relatively low, input power level. An attenuator enable signal is also supplied from a logic unit of the mobile station to enable operation of the variable attenuator circuit throughout operation in a digital mode. Thus, while enabled, as soon as the input signal power level rises above a defined activation threshold amount, the variable attenuator circuit is activated and begins attenuating the input signal responsive to input signal power levels based upon a received signal strength indication output from a separate automatic gain control circuit. After the attenuation begins gradually, thus avoiding excessive chattering without the need for hysteresis, the attenuation rises non-linearly and continuously to quickly mitigate IM distortion problems.
REFERENCES:
patent: 723075 (1991-06-01), Ishii
patent: 3624561 (1971-11-01), Tongue
patent: 4531234 (1985-07-01), Bell
patent: 4553105 (1985-11-01), Sasaki
patent: 5187809 (1993-02-01), Rich et al.
patent: 5369792 (1994-11-01), Matsumoto et al.
patent: 5438863 (1995-08-01), Durtler et al.
patent: 5465408 (1995-11-01), Sugayama et al.
patent: 5469115 (1995-11-01), Peterzell et al.
patent: 5530926 (1996-06-01), Rozanski
patent: 5697081 (1997-12-01), Lyall et al.
Bain Richard I.
Lyall, Jr. Robert L.
Nguyen Lee
Oki Telecom, Inc.
LandOfFree
Intermodulation distortion reduction circuit utilizing variable does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Intermodulation distortion reduction circuit utilizing variable , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Intermodulation distortion reduction circuit utilizing variable will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1913438