Digital amplitude modulation

摘要

A transmitter using quadrature modulation includes a rectangular to polar converter for converting data symbols into a polar form, where each polar symbol has a magnitude signal and an angle signal. Digital phase modulation circuitry includes an all digital PLL circuit for generating a phase modulated RF carrier signal responsive to the angle signal frequency control word (FCW) and a carrier frequency FCW. A digitally controlled amplifier for amplifying the phase modulated signal is controlled by a digital amplitude control circuitry for controlling the gain of the digitally controlled amplifier responsive to the magnitude signal.

主权项

1. A circuit for amplitude modulation of a signal, comprising:
circuitry for providing a digital amplitude modulation signal having a integer set of bits and a fractional set of bits, wherein the fractional portion operates at a substantially higher rate than the integer portion; a digital amplifier, coupled to receive a retimed clock signal from an input clock, comprising a plurality of switching elements for setting the output amplitude, where the switching elements are driven by respective bits of the digital amplitude modulation signal.