Gain control device for packet signal receiver
First Claim
1. A gain control device comprising:
- a variable gainamplifier for amplifying an input signal with a gain corresponding to a control voltage applied thereto;
a power detector for outputting an output voltage corresponding to an input power or an output power of said variable gain amplifier;
a control circuit for outputting the control voltage based on an output voltage of said power detector for controlling the output power of said variable gain amplifier with respect to a target value;
a packet detection circuit for detecting a packet signal by means of the output voltage from said power detector and outputting a packet detection signal;
a timing circuit for outputting a timing signal after an elapse of a predetermined time after a start of outputting the packet detection signal from said packet detection circuit;
a sample-hold circuit for sampling-and-holding the control voltage from said control circuit in response to the timing signal from said timing circuit; and
a switch circuit for providing the control voltage from said control circuit for said variable gain amplifier until the timing signal is output from said timing circuit, and providing the control voltage held by said sample-hold circuit for said variable gain amplifier in response to outputting of the timing signal.
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Accused Products
Abstract
In a gain control device for packet signal receiver, a variable gain amplifier amplifies an input signal with a gain corresponding to a control voltage applied thereto, and a power detector detects output power of the variable gain amplifier. A packet detection circuit detects a packet signal based on the detected output power. A control circuit outputs the control voltage variable with the detected output power, and the control voltage is provided for the amplifier. Thus high-speed gain control is performed immediately after the start of detection of the packet signal. When the elapsed time after the start of detection of the packet signal exceeds a predetermined time, a sample-hold circuit sample-and-holds the control voltage. This control voltage is provided for the amplifier up to the end of reception of the packet signal thereafter. Thus low-speed gain control is performed to provide stable power without distorting the signal wave.
20 Citations
5 Claims
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1. A gain control device comprising:
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a variable gain amplifier for amplifying an input signal with a gain corresponding to a control voltage applied thereto; a power detector for outputting an output voltage corresponding to an input power or an output power of said variable gain amplifier; a control circuit for outputting the control voltage based on an output voltage of said power detector for controlling the output power of said variable gain amplifier with respect to a target value; a packet detection circuit for detecting a packet signal by means of the output voltage from said power detector and outputting a packet detection signal; a timing circuit for outputting a timing signal after an elapse of a predetermined time after a start of outputting the packet detection signal from said packet detection circuit; a sample-hold circuit for sampling-and-holding the control voltage from said control circuit in response to the timing signal from said timing circuit; and a switch circuit for providing the control voltage from said control circuit for said variable gain amplifier until the timing signal is output from said timing circuit, and providing the control voltage held by said sample-hold circuit for said variable gain amplifier in response to outputting of the timing signal. - View Dependent Claims (2, 3)
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4. A gain control method for a receiver in a packet communication system in which each packet signal includes a preamble at a head and data subsequent to the preamble, the method comprising the steps of:
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amplifying a received packet signal with a gain; detecting an output power of the amplified signa; generating a control voltage variable with the detected output power; controlling the gain based on the control voltage so that the output power approaches a target value; detecting a start of the preamble of the packet signal by means of the detected output power; measuring an elapsed time after a detection of the start of the preamble of the packet signal; and
switching from high-speed gain control to low-speed gain control when the measured elapsed time exceeds a predetermined time. - View Dependent Claims (5)
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Specification