Bandpass Delta-Sigma Converters in IF Receivers

Performing the analog to digital conversion of the IF signal in a heterodyne receiver has many advantages. These advantages which include removal of DC offset and flicker noise as well as eliminating the gain mismatch in the I and Q signal paths are presented.By minimizing the quantization noise at an intermediate frequency, bandpass Delta-Sigma converters offer the most efficient method of analog-to-digital conversion of the IF signal. Moreover, due to their high resolution and linearity, bandpass Delta-Sigma converters allow a lower gain in the RF section. An IF sampling receiver architecture utilizing a sixth-order bandpass Delta-Sigma converter is presented and the circuit implementation of the receiver is discussed.