Abstract
In recent years, with the rapid development of medical technology, health care, this concept has been implemented by electronic technology to reach the targets such as small volume, portable, and long record data. Among these biomedical electronic systems, low voltage, low power consumption is one of very important design requirements. And analog-to-digital converter (ADC) plays a very important role in these systems. This thesis presents the design and implementation of a second order delta-sigma modulator, which is applied to biomedical signal acquisition devices that can handle most of the physiological signals. The entire circuit is implemented with TSMC 90nm MSG 1P9M process, by using input feed-forward architecture to reduce the integrator output swing and low quiescent current current-mirror operational transconductance amplifier (OTA) to reduce output current for system low power consumption. The 2nd order input feedforward delta-sigma modulator operating at 1V supply voltage, with 10KHz signal bandwidth, and oversampling ratio of 64, the designed modulator achieved signal to noise ratio (SNR) of 66.91 dB, signal to noise and distortion ratio (SNDR) of 64.87 dB, equivalent to the effective number of bits (ENoB) of 10.48 bits. The power consumption is 17.14 μW, the figure of merit (FoM) is 0.6 pJ/conv., and the entire chip area (including pad area) is 0.75 mm2. In addition, this thesis is also to explore some low voltage, low power consumption technologies, such as bootstrapped switch, switched-opamp technique, and opamp-shared technique, and discussing their design considerations to further improve the circuit performances in the future.