Conversion circuit for converting complex analog signal into digital representation

Abstract

A conversion circuit () for converting a complex analog input signal having an in-phase, I, component and a quadrature-phase, Q, component resulting from frequency down conversion of a radio-frequency, RF, signal (X) to a frequency band covering 0 Hz into a digital representation is disclosed. It comprises a channel-selection filter unit () arranged to filter the complex analog input signal, thereby generating a channel-filtered I and Q components, and one or more processing units (-). Each processing unit comprises four mixers (-) for generating a first and a second frequency-translated I component and a first and a second channel-filtered Q component based on two LO signals with equal LO frequency and a 90° mutual phase shift. Furthermore, each processing unit comprises a combiner unit () for generating a first, a second, a third, and a fourth combined signal proportional to sums and differences between said frequency translated I and Q components. The first and the fourth combined signals form a first complex signal, and the second and the third combined signals form a second complex signal. Each processing unit further comprises four ADCs (--) for providing digital representations of the first complex signal and the second complex signal for forming said digital representation of the analog complex input signal. A related radio receiver circuit and a related electronic apparatus are also disclosed.