Telecommunications – Receiver or analog modulated signal frequency converter – Noise or interference elimination
Reexamination Certificate
1998-06-22
2001-03-27
Eisenzopf, Reinhard (Department: 2682)
Telecommunications
Receiver or analog modulated signal frequency converter
Noise or interference elimination
C455S063300
Reexamination Certificate
active
06208849
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application entitled Receiver With Suppressed Intermodulation Distortion And Method For Operating The Same earlier filed in the Korean Industrial Property Office on Jun. 21, 1997, and there duly assigned Serial No. 97-26369 by that Office.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a receiver for a radio communication system, and in particular, to a receiver capable of suppressing intermodulation distortion signals and a method for operating the same.
2. Description of the Related Art
In a mobile communication terminal, an intermodulation distortion signal contained in a frequency band of a received RF (Radio Frequency) signal deteriorates a reception sensitivity. If the intermodulation distortion signal is greater in strength than the received RF signal, the receiver can barely detect the received signal, thus causing deterioration of the reception sensitivity. This intermodulation distortion problem is at issue in a radio communication terminal, especially, in an IS-95 dual mode (CDMA (Code Division Multiple Access) & AMPS (Advanced Mobile Phone Service)) cellular phone. For instance, in a mobile radio communication system such as a CDMA cellular system, undesired interferers (or interference signals) caused by the AMPS are intermodulated with each other, thereby generating a third order intermodulation distortion signal (i.e., the third harmonic intermodulation distortion signal). When the intermodulation distortion signal is considerably greater in strength than the CDMA signal, the reception sensitivity for the CDMA signal is lowered drastically. One process for improving the quality of a received signal in a radio receiver operating according the IS-95 standard is based on the combination of the received signal strength and signal-to-noise ratio, as contemplated by U.S Pat. No. 5,758,271 to Randall W. Rich et al. entitled Apparatus And Method for Optimizing The Quality Of A Received Signal In A Radio Receiver, incorporated herein by reference. U.S Pat. No. 5,697,081 to Robert L. Lyall, Jr. et al. entitled Intermodulation Distortion Reduction Circuit Utilizing Variable Attenuation contemplates a process wherein a variable attenuator, responsive to received signal strength in a receiver, provides variable attenuation to reduce intermodulation distortion according to an IS-98 standard. Reduction of intermodulation distortion is also contemplated by U.S. Pat. No. 5,564,094 to George C. Anderson et al. entitled Radio Receiver Providing Reduced Intermodulation Distortion; U.S. Pat. No. 5,001,776 to Edward T. Clark entitled Communication System With Adaptive Transceivers To Control Intermodulation Distortion; and U.S. Pat. No. 5,170,392 to Kenneth B. Riordan entitled Intermodulation Compensation In A Receiver.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a receiver for use in a radio communication system, capable of preventing deterioration of the reception sensitivity due to the intermodulation distortion signals, and a method for operating the same.
It is another object of the present invention to provide a receiver for use in a radio communication system, having a low noise amplifier and an IF amplifier, wherein operating voltages and currents of the low noise amplifier and the IF amplifier are increased subsequently to enhance the reception sensitivity when the reception sensitivity is lowered due to the intermodulation distortion signals, and a method for operating the same.
It is still another object of the present invention to provide a receiver for use in a radio communication system, having a low noise amplifier, an IF amplifier, and an attenuator disposed between the low noise amplifier and the IF amplifier, wherein operating voltages and currents of the low noise amplifier and the IF amplifier are increased subsequently to enhance the reception sensitivity and then the attenuator is driven, when the reception sensitivity is lowered due to the intermodulation distortion signals, and a method for operating the same.
To achieve the above objects, there is provided a receiver with suppressed intermodulation distortion for a radio communication terminal. The receiver includes a low noise amplifier for low-noise-amplifying a received signal, an operating power thereof being increased to reduce an intermodulation distortion signal in response to a first control signal; an RF bandpass filter for bandpass-filtering signals in a reception frequency band out of the signals output from the low noise amplifier; a mixer for mixing an output of the RF bandpass filter with a local oscillation signal to generate an IF signal by down-converting the output of the RF bandpass filter; an IF amplifier for amplifying the IF signal output from the mixer, an operating power there of being increased to reduce the intermodulation distortion signal in response to a second control signal; an IF bandpass filter for bandpass-filtering an IF signal out of the signals output from the IF amplifier; a demodulator and signal processor for demodulating and processing the IF signal output from the IF bandpass filter to generate an RSSI signal and a signal-to-noise ratio signal; and a controller having a reference RSSI signal and a reference signal-to-noise ratio signal stored therein, for comparing the RSSI signal and the signal-to-noise ratio signal with the reference RSSI signal and the reference signal-to-noise ratio signal to determine whether a reception sensitivity is poor, and activating the first and second control signals if the reception sensitivity is poor.
REFERENCES:
patent: 5001776 (1991-03-01), Clark
patent: 5170392 (1992-12-01), Riordan
patent: 5222255 (1993-06-01), Kuo et al.
patent: 5239683 (1993-08-01), Usui
patent: 5339454 (1994-08-01), Kuo et al.
patent: 5361395 (1994-11-01), Yamamoto
patent: 5564094 (1996-10-01), Anderson et al.
patent: 5697081 (1997-12-01), Lyall, Jr. et al.
patent: 5758271 (1998-05-01), Rich et al.
patent: 5862465 (1999-01-01), Ou
patent: 5873046 (1999-02-01), Bronner
patent: 5991612 (1999-11-01), Saito
patent: 6011980 (2000-01-01), Nagano et al.
patent: 6035008 (2000-03-01), Kim
patent: 6044253 (2000-03-01), Tsumura
patent: 6052566 (2000-04-01), Abramsky et al.
Cho Seong-Won
Kim Hong-Gyu
Kwon Sung-Taek
Park Jae-Sun
Bushnell , Esq. Robert E.
Eisenzopf Reinhard
Mehrpour N.
Samsung Electronics Co,. Ltd.
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