Vector FM modulator

摘要

A cellular-telephone transmitter (10) employs a vector modulator (14). An integrating circuit (52) generates the integral of the message signal and applies it to circuitry (54, 56) for generating in-phase and quadrature modulation signals representing the cosine and sine, respectively, of the integrating-circuit output. The vector modulator (14) produces the desired FM signal by adding together quadrature and in-phase versions of a carrier in proportion to the values that the quadrature and in-phase modulating signals represent.