In-phase/quadrature modulator has FIR filter in branch(es) before ADC with phase frequency characteristic to compensate disturbing frequency characteristic in sideband suppression

摘要

The device has separate in-phase and quadrature branches with modulator stages receiving in-phase and quadrature signals via ADCs and modulating them onto a high frequency carrier with carrier signals in quadrature to each other. A FIR filter is arranged in at least one branch before the ADC with phase frequency characteristic selected so that a disturbing frequency characteristic in the sideband suppression is compensated. The device has separate in-phase and quadrature branches (4,7) with modulator stages (1,2) receiving the in-phase and quadrature signals via analogue to digital converters (5,8) and modulating them onto a high frequency carrier with carrier signals in quadrature to each other. A digital finite impulse response or FIR filter (10) is arranged in at least one of the branches before the analogue to digital converter with phase frequency characteristic selected so that a disturbing frequency characteristic in the sideband suppression is compensated.