Design of wideband mixer and VGA for Software Defined Radio in RFID application

This paper presents Software Defined Radio (SDR) in RFID sensing applications focusing on wideband mixer and VGA design. The wideband receiver can support UHF, UWB band for commonly used long-range RFID standards ranging from 400MHz to 6GHz. The wideband mixer is of folded topology with switching biased technique, achieving a maximum 11.5dB conversion gain with only an 8dB DSB noise figure and 16dB flicker noise at 10kHz. The VGA utilizes a four-stage modified Cherry-Hopper amplifier, along with DC-offset cancelling and common-mode feedback. A maximum gain of 67dB can be achieved with more than 600MHz of bandwidth. The design is implemented in a 65nm CMOS process. The total power consumption of the mixer and the VGA is 7mW by simulation. The die area of these two blocks is 0.045mm².