Texas Instruments Incorporated
Carrier frequency recovery in a receiver

Abstract:

In described examples, a method of operating a transmitter includes generating a frequency reference signal having a reference frequency and outputting the frequency reference to a phase locked loop (PLL) that includes a voltage controlled oscillator (VCO). The VCO output is locked to the frequency reference signal to form a carrier signal. The transmitter receives an I input signal, a Q input signal, and a direct current (DC) leaky carrier signal. Either the I input signal or the Q input signal is added to the leaky carrier signal. The carrier signal is modulated with the resulting two signals using an I-Q mixer to generate a modulated signal that includes an unmodulated carrier signal component. The modulated signal is then transmitted.