| 摘要 |
A wideband impedance attenuator includes a phase-locked loop filter, a voltage-controlled oscillator connected to the phase-locked loop filter during transmit, and an impedance circuit connected to the phase-locked loop filter and the voltage controlled oscillator. The impedance circuit is a scaled version of the phase-locked loop filter. Moreover, the wideband impedance attenuator attenuates a Gaussian frequency shift key modulation signal by a factor of 1/(N+1) using the impedance circuit, which has an impedance of N*Z(s), and the phase-locked loop filter, which has an impedance of Z(s). An output frequency is generated using a voltage-controlled oscillator wherein the output frequency corresponds to the attenuated Gaussian frequency shift key modulation signal. In addition, a comparator compares a voltage of an output from the programmable gain amplifier with a voltage necessary to produce a predetermined frequency shift in a voltage-controlled oscillator to produce a gain signal. A gain controller, in response to the gain signal produced by the comparator, controls a gain of the programmable gain amplifier.
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