| 摘要 |
PURPOSE: A baseband automatic gain control apparatus is provided to detect a strength of a receive signal without using a ROM table by using a multiplier to detect power of receive signal. CONSTITUTION: A voltage control amplifier(VCA) amplifies a receive signal(RxIF) according to a magnitude of an applied control voltage. A demodulator(1) outputs an in-phase(I) and a quadrature phase(Q) through different paths according to an output of the voltage control amplifier. Amplification parts(AMP1,AMP2) amplify the in-phase(I) and the quadrature phase(Q) of the demodulator(1), and low pass filters(LPF1,LPF2) filter outputs of the amplification parts(AMP1,AMP2). Analog to digital converters(ADC1,ADC2) convert outputs of the low pass filters into digital signals. A multiplexor(MUX) selectively outputs output signals of the analog to digital converters. A baseband power detecting part(2) receives output signals of the analog to digital converters to detect a strength of the receive signal. A digital to analog converter(DAC1) converts an output signal of the digital to analog converter into an analog signal. An integrator(3) integrates an output signal of the digital to analog converter according to a predetermined function and applies an integration value as the control voltage of the voltage control amplifier.
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