A Low-Power Compact IEEE 802.15.6 Compatible Human Body Communication Transceiver With Digital Sigma–Delta IIR Mask Shaping

Abstract

Human body communication (HBC) will play an important role in wireless body area networks (WBANs) because of its low power and low hardware cost. However, the low-frequency band of HBC transmitting signal could potentially interfere with the vital signs such as electrocardiography (ECG) and electromyography (EMG), especially for the frequency below 2 MHz. In this paper, a new mask-shaping technique is proposed for the HBC transmitter to suppress the mask below 2 MHz, where a digital sigma-delta truncated infinite impulse response (SDTIIR) filter provides sufficient rejection with a digital-to-analog converter (DAC) of only 8 bits. To save the die area, a single-ended receiver is designed with dc-coupled blocks, whereas a digital calibration technique is employed to eliminate the static dc offset. The proposed techniques are implemented in the 65 nm CMOS process, demonstrating a sub-millimeter-sized IEEE 802.15.6 compatible HBC transceiver chip. Measurements show that the transmitter achieves a rejection of -86.5 dBr at 2 MHz with 3.52 mW power. Consuming 620 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</sub> W , the receiver achieves a sensitivity of -72 dBm at a chip rate of 5.25 Mc/s and a bit error rate (BER) less than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> .