| 摘要 |
A multi-band transceiver for receiving and transmitting signals within selected GSM frequency bands. Transmission and reception occurs simultaneously and within the same time slot of a TDMA frame. The transceiver includes a first local oscillator LO1 that selectively oscillates within a bandwidth corresponding to the selected GSM band and outputs a signal having a frequency fLO1. A second local oscillator LO2 selectively oscillates at a frequency corresponding to the selected GSM band and outputs a signal having a frequency fLO2. A receiver receives a signal having a frequency fRx and mixes the signals from the first and second local oscillators to generate a demodulating signal having a frequency fRx, wherein fRx=fLO1±fLO2. A transmitter having a loop architecture includes a VCO that generates a signal having a transmit frequency fTx equal to fRx minus a comparison frequency fCF, and a mixer that mixes the signal from the first local oscillator with the transmit signal to generate an IF signal having a frequency fIF=fLO2±fCF. A quadrature mixer that modulates the IF signal with baseband "I" and "Q" signals, and a phase detector that compares the phases of the IF signal and the signal from the second local oscillator and outputs a control voltage to the VCO.
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