A 2.4‐mW interference‐resilient receiver front end with series N‐path filter–based balun for body channel communication

Abstract

SummaryThis paper presents an interference‐resilient receiver front end for body channel communication, which uses the human body as the signal transmission medium in the band of 40 to 60 MHz. To tackle strong out‐of‐band interference resulting from the human body antenna effect, a series N‐path filter–based balun preceding a low‐noise amplifier is proposed to improve the frequency modulation radio interference suppression and realize single‐to‐differential transformation of input body channel communication signals. Besides, an enhanced harmonic rejection with combination of a series N‐path filter and a harmonic rejection passive mixer using 8‐phase 12.5% duty‐cycle clocks as local oscillator is presented. The transconductance amplifier sharing is used to reduce the power consumption of the mixer. Fabricated in a standard 0.18‐μm complementary metal‐oxide‐semiconductor process, the proposed receiver front end occupies an area of 780 × 660 μm2 including pads. Operating at 50 MHz, the front end consumes 1.35 mA from a 1.8‐V supply and achieves a maximum gain of 50.5 dB with a noise figure of 11.2 dB, 28.5 dB frequency modulation interference suppression at the second‐order harmonic rejection, and 53.9 dB at the third‐order harmonic rejection.