Transmitter device with quasi-constant lo leakage, for wireless communication equipment with a direct conversion architecture

Abstract

A transmitter device for wireless communication equipment, comprises at least one path (P) comprising i) a low-pass filter (LPF, LPF−) for filtering differential signals and applying a chosen first attenuation to each of them to decrease their amplitudes, ii) a differential transconductor (TC, TC−) arranged for applying a chosen second attenuation to each differential signal coming from the low-pass filter (LPF, LPF−) to decrease its continuous component, and iii) a mixer (M) for mixing separately the differential signals delivered by the transconductor with local oscillator carriers at a chosen radio frequency to deliver output RF signals to be transmitted. The transconductor (TC, TC−) comprises two original cells (OC) for defining two original signals from the differential signals having the first attenuation, and N first and N second signal copy cells (CC-CC) each arranged for generating a copy of one of the original signals. The number of signal copy cells used defines the second attenuation and the first and second attenuations to be applied are chosen so that the value (defined by the offset between the continuous component of the differential signals delivered by the transconductor divided by the amplitude of one of these signals) stays below a chosen maximum value over the whole gain range of the path.