Patent ID: 7010280

Claim:
A linear RF transmitter for the transmission of non-constant envelope modulated signals comprising: baseband processing means arranged to resolve an input signal into a phase component, and to further resolve the phase component into In-phase (I) and quadrature (Q) components; conversion means arranged to generate analogue representations of the signal components; phase modulation means arranged to receive the analogue representations of the In-phase and quadrature components and to upconvert and phase modulate the I and Q components into an RF signal, further comprising a first oscillator arranged to produce an intermediate frequency signal; a first IQ modulator means to phase modulate the intermediate frequency signal with the I and Q signal components; a second oscillator arranged to produce a reference frequency signal; and a phase lock loop to upconvert the modulated intermediate frequency signal to the radio frequency; said phase modulation means further comprising binary modulator means arranged to receive the phase modulated RF signal and to be controlled by the baseband processing means to remove any 180 degree phase shifts introduced by the phase modulated RF signal; the upconverted intermediate frequency signal is output as the phase modulated RF signal at a frequency the sum of the intermediate frequency and the reference frequency; output power amplifier means arranged to receive the phase modulated RF signal and amplify the signal for transmission; direct amplitude modulation means arranged to receive an amplitude component of the input signal and to control the output power amplifier means in accordance with the amplitude component whereby to amplitude modulate the RF signal; and synchronising means arranged to monitor the RF signal and control the conversion means in response to the RF signal, wherein the baseband processing means are further arranged to resolve the amplitude component from the input signal, and the conversion means are further arranged to generate an analogue representation of the amplitude component and feed the analogue representation to the direct amplitude modulating means.