Telecommunications – Receiver or analog modulated signal frequency converter – Local control of receiver operation
Reexamination Certificate
1998-12-29
2001-11-27
Bost, Dwayne (Department: 2681)
Telecommunications
Receiver or analog modulated signal frequency converter
Local control of receiver operation
C455S232100, C455S234200, C455S247100, C455S246100, C455S250100, C375S345000
Reexamination Certificate
active
06324387
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to radio communication, and more particularly, to power control in a receiver having a low noise amplifier (LNA) with an adjustable gain which is controlled by a closed loop automatic gain control (AGC).
2. Discussion of the Prior Art
Several different modulation schemes are used for wireless mobile phones. One modulation method is the code division multiple access (CDMA) scheme where signals are broadband and occupy several channels. This is in contrast to the frequency division multiple access (FDMA) scheme where signals are narrowband and occupy one channel at a time. For optimal performance in wireless phones using CDMA, the power level of transmitted signals within the channels must be carefully controlled.
In a CDMA network, an induced interference, e.g. from other competing networks such as from the Advanced Mobile Phone Service (AMPS), has been recognized to have an adverse effect on the voice quality. Theoretically this interference can be minimized by allocating to each operator a dedicated spectrum. However, a mobile station (MS) experiences the competitor induced interference when the MS comes within a close vicinity of the competitor base station. This degrades performance and even causes a drop call where a call is lost.
Although, the competitor's interference resides on different spectrum, the nonlinearity in the receiver's components, e.g. the low noise amplifier (LNA), causes intermodulation, referred to as MIM, which is a source of co-channel and adjacent channel interference. The major source of MIM is the LNA. The present invention is related to a technique which minimize co-channel interference and hence increases the performance of the receiver.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a controlled receive device and control method which eliminates the problems of conventional receive devices.
Another object of the present invention is to provide a controlled receive device and method having minimal performance degradation.
A further object of the present invention is to provide a controlled receive device and method which minimizes out of band interferences and increase the performance of a receiver.
A still further object of the present invention is to provide a controlled receive device and method which dynamically adjust the gain of a low noise amplifier (LNA) to an optimal value by discrete gain-steps.
The present invention accomplishes the above and other objects by providing a controlled receive device having an amplifier circuit, which receives an input signal, and a control circuit which receives the input signal and outputs a controlled signal to a receiver. The receiver outputs an output signal. A controller varies the gain of the amplifier circuit in response to levels of the controlled signal and the output signal.
The control circuit outputs a controlled indicator signal indicative of a level of the controlled signal and the receiver outputs an output indicator signal indicative of the output signal level. The controlled indicator signal and the output indicator signal are compared, e.g., using comparators, to respective reference or threshold levels for producing control signals used by the controller for varying the amplifier gain.
Illustratively, the controller decreases the amplifier gain when the output signal is less than an output threshold level and the controlled signal is greater than a controlled threshold level. Further, the controller increases the amplifier gain when the output signal is less than the output threshold level and the controlled signal is less than the indicator threshold level. Further, the controller keeps the amplifier gain unchanged when the output signal is greater than the output threshold level.
In another embodiment, a control method is disclosed which includes the steps of:
increasing a gain of an amplifier circuit which receives an input signal when a controlled signal from a control circuit connected to the amplifier circuit is less than a controlled threshold level and an output signal of a receiver connected to the control circuit is less than an output threshold level; and
decreasing the gain when the controlled signal is greater than the controlled threshold level and the output signal is less than the output threshold level.
A further steps includes maintaining the gain unchanged when the output signal is greater than the output threshold level.
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Kamgar Farbod
Motamed Mariam
Rouphael Antoine J.
Bost Dwayne
Halajian Dicran
Philips Electronics N.A. Corp.
West Lewis G.
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