| Lower supply voltage and higher integration are used in the very large integrated (VLSI) circuit design to reduce the power dissipation and to improve the system portability. Given current trends, technology development will eventually make it possible for a complex system to be integrated onto a single chip. Such a system will usually contain a powerful core for data processing and some peripheral circuits for the interface between the system and the outside world. The entire system will be powered by a single battery. This system-on-a-chip approach is very attractive for higher system portability, lower power and lower fabrication cost. There have been some major challenges associated with such an approach. One of them is the design of the analog periphery circuits which usually determines the overall performance of the system. The current mode circuit, in which the signal is represented by current instead of voltage, offers a solution to the problem. In a current mode circuit, signal dynamic range can be maintained while reducing the supply voltage and power. Furthermore, it is fully digital CMOS compatible since no resistors and capacitors are required in the design.;In this dissertation, CMOS analog circuits including a current division D/A converter, a current mode A/D converter, signal conditioner/preamplifier, and radio frequency (RF) transmitter are presented. Their low voltage/power operation capabilities are investigated. Circuit analysis, simulation verification, implementation, fabrication, circuit testing results and further recommendations are presented. In addition, a single chip bio-data acquisition system consisting of signal conditioning, A/D conversion, and frequency shift keyed (FSK) RF transmission circuits was developed. |
