Projeto de um receptor BFSK integrado para HBC baseado na técnica injection locking

Abstract

Telecommunication technologies have advanced to the point of enabling networks specialized in data transmission in close proximity to the body. This method of communication, known as Body Area Network (BAN), is evolving rapidly, demanding greater portability and longer battery life. This, in turn, drives the need for reduced power consumption. For this reason, solutions have been studied over the last three decades to improve energy efficiency in signal transmission. Among these technologies, the Human Body Communication (HBC) technique stands out in recent academic research. HBC is a wireless communication method for body networks that offers advantages in terms of consumption, security, and interference compared to other radiation-based methods. This advantage comes from using the human body as a signal transfer channel. In this paper, we describe the design and post-layout simulations of a receiver for HBC with capacitive coupling, developed in 180 nm CMOS technology, capable of demodulating BFSK signals. We employ an architecture that performs frequency-phase conversion, exploiting the phenomenon of injection locking. The designed receiver incorporates an input amplifier to raise the received signal to the levels required for injection locking in a Voltage Controlled Oscillator (VCO). With injection locking, a phase difference will be present between the VCO signal and the injected signal. This phase difference is identified by a phase detector, which determines whether the VCO signal is delayed or advanced. After filtering and comparing the output signals of the phase detector, BFSK signal demodulation is obtained. Post-layout simulations of the circuit demonstrate the receiver's ability to operate in the range between 40 and 60 MHz, with data rates of up to 5 Mbps, power consumption between 0.74 mW and 1.58 mW, and communication efficiency between 148 pJ/bit and 316 pJ/bit, with power supply of 1.5 V and 1.8 V, respectively. The study conducted in this work enhances the knowledge of receiver design for HBC by demonstrating a pathway for improving energy consumption in wireless signal communication, enabling its use in BANs in medical, security, or entertainment applications.