Design of Low-Power Direct-Conversion RF Front-End With a Double Balanced Current-Driven Subharmonic Mixer in 0.13 $\mu {\rm m}$ CMOS

A 402-MHz fully differential RF front-end was designed and implemented using 0.13 μm CMOS process. This design was targeted for low-power and low-cost direct conversion applications such as short-range radio in biomedical devices. This RF front-end consists of a differential CG-CS LNA with a positiveor negative-feedback technique and a frequency doubler subharmonic quadrature passive mixer. The subharmonic conversion passive mixer driven by current input signals (from a transconductor) and loaded with low impedance is implemented to minimize the LO self-mixing dc-offset and introduces a high linearity. The front-end was implemented on a 0.13 μm CMOS process and occupies 380μm × 330 μm active chip area, which is approximately 50% of that of the conventional front-end. The RF front-end achieves 31 dB conversion gain, 13.6 dB noise figure (NF) and an in-band IIP3 of 3 dBm. The design consumes 2.25 mA from a 1.2 V power supply.