Patent ID: 7206557
Filing Date: 2007-04-17
Classification: H04B

Abstract:
1. A direct conversion transmitter comprising: an in-phase local oscillator and a quadrature local oscillator to generate local oscillator signals, the in-phase local oscillator and a quadrature local oscillator electrically coupled to an in-phase mixer and a quadrature mixer; an in-phase modulating signal and a quadrature modulating signal electrically coupled to an in-phase summer and a quadrature summer, the in-phase modulating signal and quadrature modulating signal utilized to modulate the local oscillator signals; the in-phase mixer and a quadrature mixer for mixing the modulating signals with the local oscillator signals to generate a modulated in-phase signal and a modulated quadrature signal at the local oscillator frequency; a radio frequency (RF) combiner electrically coupled to the output of the in-phase mixer and the quadrature mixer, the RF combiner to combine the modulated in-phase signal and the modulated quadrature signal to generate a carrier suppressed modulated signal; a leakage detector electrically coupled to the output of the RF combiner, downstream of the RF combiner, the leakage detector measuring the magnitude of carrier signal in the carrier suppressed modulated signal during transmission; a correction algorithm processor electrically coupled to the leakage detector, the correction algorithm processor running a correction algorithm to calculate values utilized to generate an in-phase digital correction signal and a quadrature digital correction signal; an in-phase digital to analog converter (DAC) and a quadrature DAC electrically coupled to the in-phase and quadrature outputs of the correction algorithm processor, the in-phase DAC and the quadrature DAC controlled by the correction algorithm processor, the in-phase digital to analog converter (DAC) and quadrature DAC generating an in-phase corrective signal and a quadrature corrective signal; the in-phase summer and quadrature summer electrically coupled to the in-phase mixer and a quadrature mixer, the in-phase summer and quadrature summer for adding the in-phase corrective signal and the quadrature corrective signal to the in-phase modulating signal and the quadrature modulating signal, respectively, before the signals are mixed; and an antenna to transmit the carrier suppressed modulated signal, wherein the in-phase correction signal and the quadrature correction signal are electrical currents, and wherein the magnitude of the carrier signal is measured at least once per data frame, and the in-phase correction signal and quadrature correction signal are calculated once per data frame.