Switched-current analog-to-digital conversion techniques

Modern day communication and instrumentation systems make greater use of digital technology that is integrated onto VLSI systems. Such technology entails the need for analog-to-digital (A/D) and digital-to-analog (D/A) converters in order to interface with the outside world. Speed, area, power consumption, and resolution are some of the important issues in the design of the data converters so that they can be more efficiently integrated into systems.;In mixed mode design (analog/digital), it is desired to have analog sub-systems that are small in area and fully compatible with present digital VLSI technology. In analog circuit design, the voltage mode methodologies have traditionally been used for signal processing. In voltage mode designs, the switched-capacitor (SC) technique has been extensively used. However, SC circuits require high quality analog components and good matching characteristics. Standard digital VLSI technology may not achieve these requirements for the SC circuits resulting in reduced performance. An alternative way for implementing analog signal processing circuits is to use current mode techniques where current rather than voltage is used to transmit information. The switched current (SI) technique offers full compatibility with digital VLSI processes, potential simplicity of circuit implementation, and low power consumption. Current mode analog design overcomes some of the problems associated with voltage mode design while attempting to use digital VLSI technology to implement the analog circuits.;This research focuses on A/D conversion techniques for improving the performance of the converter using SI approaches which are compatible with the present VLSI technology. Different structures of A/D converters have been developed to enhance the A/D performance. One of the structures is a non-restoring cyclic conversion technique which requires three steps for one bit conversion. This conversion technique demonstrates a resolution of 13 bits. Two types of second-order SI sigma-delta converter are proposed to improve the performance of the converters. Both of the second-order modulators demonstrate about 85dB dynamic range at audio range speed. One of the second-order modulators has been designed, simulated, and fabricated using MOSIS 2-...