An Input Amplifier for Body-Channel Communication

Sammanfattning: Body-channel communication (BCC) is based on the principle of electrical field data transmission attributable to capacitive coupling through the human body. It is gaining importance now a day in the scenario of human centric communication because it truly offers a natural means of interaction with the human body. Traditionally, near field communication (NFC) considers as a magnetic field coupling based on radio frequency identification (RFID) technology. The RFID technology also limits the definition of NFC and thus reduces the scope of a wide range of applications. In recent years BCC, after its first origin in 1995, regain importance with its valuable application in biomedical systems. Primarily, KAIST and Philips research groups demonstrate BCC in the context of biomedical remote patient health monitoring system. BCC transceiver mainly consists of two parts: one is digital baseband and the other is an analog front end (AFE). In this thesis, an analog front end receiver has presented to support the overall BCC. The receiver (Rx) architecture consists of cascaded preamplifier and Schmitt trigger. When the signals are coming from the human body, they are attenuated around 60 dB and gives weak signals in the range of mV. A high gain preamplifier stage needs to amplify these weak signals and make them as strong signals. The preamplifier single stage needs to cascade for the gain requirement. The single stage preamplifier, which is designed with ST65 nm technology, has an open loop gain of 24.01 dB and close loop gain of 19.43 dB. A flipped voltage follower (FVF) topology is used for designing this preamplifier to support the low supply voltage of 1 V because the topology supports low voltage, low noise and also low power consumption. The input-referred noise is 8.69 nV/sqrt(Hz) and the SNR at the input are 73.26 dB. The Schmitt trigger (comparator with hysteresis) is a bistable positive feedback circuit. It builds around two stage OTA with lead frequency compensation. The DC gain for this OTA is 26.94 dB with 1 V supply voltage. The corner analyzes and eye diagram as a performance matrix for the overall receiver are also included in this thesis work.