Image-reject receivers with image-selection functionality

Two image-reject receiver implementations based on the Hartley architecture are presented in this paper. The concept of image selection is introduced and various implementation methods are discussed. Both designed receiver circuits include a LNA, two mixers, a polyphase filter as a combiner, an IF amplifier and a frequency divider chain for LO generation. The first circuit implementation has a measured gain of 46 dB, an image-rejection-ratio >40 dB and a noise figure of 6 dB at the 700 MHz input frequency and 40-MHz IF frequency. Correspondingly, the second receiver has a 52-dB gain, an image-rejection-ratio >16 dB and a noise figure =6 dB. The circuits were fabricated in a 0.9-μm SiGe bipolar process