This paper presents an even harmonic mixer using self-biased anti-parallel diode pair (APDP). A proposed self-biased APDP is composed of a pair of diodes and self-bias series resistors. At high LO injection level, rectified current is generated by the diodes and reverse voltage is applied to the diodes by the self-bias resistor. Therefore, rapid degradation of conversion loss at high LO input level can be avoided. The effect of self-bias resistor is explained by using simplified behavior model and harmonic balance method, and is evaluated by the measurements of an L-band even harmonic type direct conversion mixer.

This paper presents an even harmonic quadrature mixer (EH-QMIX) with a simple filter configuration and an integrated LTCC module including LNAs, band rejection filters (BRFs), and the proposed EH-QMIX for W-CDMA direct conversion receiver (DCR). Since the DCR has no spurious responses, a BRF instead of a high-Q band pass filter can be applicable for eliminating undesired signals and it can be built in the LTCC substrates easily. As LO frequency is half of RF frequency in the EH-QMIX, diplexer can be composed of simple filters and it can be also integrated in the substrates. As a result, the whole RF circuits of the EH-DCR using a proposed EH-QMIX are integrated in the LTCC module and miniaturization of the receiver is achieved. Moreover, in order to suppress the degradation of the amplitude and the phase imbalances in the quadrature mixer caused by interferences of signals, RF characteristics of the circuits in the mixer such as reflection coefficients, isolations are discussed. A developed LTCC module shows good performances for W-CDMA direct conversion receiver.