Patent ID: 7424064

Claim:
A polar transmitter for transmitting radio frequency (RF) signals, said transmitter comprising: a carrier frequency generator comprising a generator input for receiving a signal indicative of a phase data part, wherein the radio frequency signals are based on a first digital baseband signal and a second digital baseband signal, the second baseband signal having a phase shift from the first baseband signal, and the radio frequency signals comprise a carrier frequency, and wherein the first baseband signal and the second baseband signal are converted into baseband signals in a polar form having an amplitude data part and the phase data part, the carrier frequency generator further comprising a generator output for providing the carrier frequency modulated by the phase data part; and a digital-to-RF conversion section for converting the carrier frequency modulated by the phase data part into phase-modulated signals so that the amplitude data part is caused to impose on the phase-modulated signals for providing the RF signals, the digital-to-RF conversion section comprising: a carrier input having two input ends to receive a carrier signal indicative of the carrier frequency modulated by the phase data part, a data input to receive a data signal indicative of the amplitude data part, the data signal having a plurality of data bits, and a conversion component adapted to convert the data signal for providing a differential output signal modulated by the carrier signal, the differential output signal indicative of the phase-modulated signals, formed with current loads and provided between two output ends, the conversion component comprising: a plurality of conversion units connected in parallel, each unit adapted to receive a voltage indicative of a data signal value indicative of the data bits, the voltage provided between two voltage input ends, each unit comprising: a first differential switch section having: two input current paths, each operatively connected to a different one of the output ends; and two differential switch pairs connected to the voltage input ends for conveying in the two input current paths differential currents indicative of the data signal value; a second differential switch section having two current paths, each operatively connected in series to a different one of the two differential switch pairs, the current paths operatively and separately connected to different ones of the carrier signal ends, for modulating the differential currents with the carrier signal; and a current source, operatively connected in series to the second differential switch section for controlling currents in the current paths.