Invention Grant
US08442466B2 FM transmitter with a delta-sigma modulator and a phase-locked loop 有权
FM发射机,带有Δ-Σ调制器和锁相环

FM transmitter with a delta-sigma modulator and a phase-locked loop
Abstract:
A frequency modulation (FM) transmitter implemented with a delta-sigma modulator and a phase-locked loop (PLL) is described. The delta-sigma modulator receives a modulating signal (e.g., an FM stereo multiplex (MPX) signal) and provides a modulator output signal. The PLL performs frequency modulation based on the modulator output signal and provides an FM signal. The FM transmitter may further include a gain/phase compensation unit and a scaling unit. The compensation unit may compensate the modulating signal for the closed-loop response of the PLL. The scaling unit may scale the amplitude of the modulating signal based on a gain to obtain a target frequency deviation for the FM signal. The PLL may operate in a transmit mode or a receive mode, may perform frequency modulation in the transmit mode, and may provide a local oscillator (LO) signal at a fixed frequency in the receive mode.
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