Circuit techniques to improve the linearity of an up-conversion double balanced mixer with an active balun using InGaP/GaAs HBT technology

This paper describes two circuit techniques to improve the linearity of an up-conversion double balanced mixer (DBM). These techniques are optimized for dual-band operation in PCS and IMT-2000 applications. Also, the integrated active balun is used at the RF port to produce a single-ended RF output signal. To improve the linearity of the mixer, the emitter degeneration resistors and the current injection resistors are used. The DBM with both resistors shows an improved IIP3 from -7.0 dBm to 6.5 dBm and P_1dB increases from -15 dBm to -4 dBm. Furthermore, a DBM which uses only the emitter degeneration resistor has been fabricated using an InGaP/GaAs HBT process.