Development and Verification of Low Power Analog Front End CMOS Circuits for Biomedical Applications

Abstract

The portable, wearable and implantable biomedical devices are small in size and newlinemostly battery operated or self-powered. The weight and size of such systems are newlinedependent on the battery. Lower the power consumed by the circuits, smaller will be newlinethe battery size and more energy efficient. The energy efficiency of the system newlinedepends on task performed, technology used to implement, architecture or topology newlinebeing used, speed or the bandwidth of the task, precision requirement of the task. In newlinethe design of energy efficient systems, low power Analog Front End (AFE) circuits newlinecan significantly contribute for the reduction of overall power consumption of the newlinesystem. The task of signal acquisition and preprocessing is done by the AFE of the newlinesystem. The sensors and electrodes interface the physiological system to the newlinebiomedical device and pick up the signals. These signals are given to the AFE circuits newlinefor analog preprocessing. The AFE need to remain on all the time to process the newlinebioelectric signals continuously sensed by the sensors and electrodes. Therefore, they newlineconsume a major portion of the overall power budget of the system. newlineThe analog preprocessing includes removal of noise, amplification and filtering of the newlinesignal captured by the sensors and electrodes. An AFE for biomedical signal newlineprocessing, consists of a low-noise pre-amplifier (LNA), a filter, a variable gain newlineamplifier. The low noise amplifiers (LNA) of AFE are designed with high CMRR, newlinegood range of ac voltage gain, maximum output swing, low input offset voltage and newlinehigh input impedance. The range of frequency of biomedical signals vary from few newlineHz to kHz. Depending on the type of the biomedical signals and their sensing newlinemechanisms, active filters with very low cut-off frequencies ranging from DC to less newlinethan 2 kHz are required. In this thesis, CMOS operational transconductances and newlinemultifunction analog filters are designed using low voltage and low frequency newlinetechniques. The scope of this thesis is to design, verify and study the performance newlineparameters to suit