Texas Instruments Incorporated
Transceiver carrier frequency tuning

Abstract:

In described examples, a method of operating a transceiver with a transmitter and a receiver includes generating a frequency reference. In the transmitter: A phase locked loop (PLL) generates a first voltage controlled oscillator (VCO) control voltage responsive to the frequency reference. A VCO in the transmitter generates a transmitter VCO signal responsive to the first VCO control voltage, and the PLL is locked to the transmitter VCO signal. In the receiver: A signal is received. A receiver VCO generates a receiver VCO signal responsive to the first or a second VCO control voltage. The receiver VCO signal is multiplied by the received signal to generate an I component, and by the received signal phase shifted by 90.degree. to generate a Q component. The second VCO control signal is generated responsive to the I component and the Q component.