Novel sub-harmonically pumped mixers incorporating dual-band quarter-wave and in-line stub

Sub-harmonically pumped (SHP) mixers with very low conversion loss are developed. These mixers entail the use of novel dual-band quarter-wave stubs and in-line stub simultaneously providing return paths for the IF, LO and RF frequencies and terminating unwanted frequency mixing products. These stubs are realized in the form of compact microstrip resonant cells with spiral patterns. The measured 4.1 dB conversion loss at 11.8 GHz RF signal of our new 2/sup nd/ SHP mixer outperforms typical designs of 8-10 dB. The 8/sup th/ SHP mixer designed at 44 GHz RF signal achieves a simulated minimum conversion loss of 9.5 dB. These novel designs provide viable solutions to low-cost high-performance wireless communications subsystems.