Low voltage analog circuit design /
There is a strong demand for low power mixed signal
| Main Author: | |
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739669341&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | There is a strong demand for low power mixed signal applications, such as mobile communication and other portable systems. In these applications, the supply voltage is being scaled down to reduce the power consumption. As for the process, digital CMOS is always the preferred technology. Analog circuits must operate with the low supply voltage and should be realized in a digital process. This leads to significant performance degradation of the analog circuits. The objective of this research is to study the theory and design of low voltage op amps, which are the most important building blocks in analog systems. Two categories of low voltage op amp have been investigated. The first category operates with 3.OV power supply. The distinct features of this class of op amps are the input stages using N-P complementary pairs and the gain stages using the active gain enhancement. It was found from this research that the input stages using N-P pairs will suffer from severe CMRR degrada tion. A detail theoretical analysis has revealed the effect of mismatch and the circuit topology on the CMRR. The active gain enhancement technique is found to cause instability problems. Conditions for stabilizing these amplifiers have been proposed. A design procedure has also been provided. The second class of op amps operate with 1.5V power supply. This class of op amps must depend on multistage cascading for a high gain. Some special compensation techniques must be incorporated to ensure the stability- This research has resulted in a new amplifier topology with Nested Gm-Capacitor Compensation (NGCC), which proves to have several advantages over the conventional topologies. To realize the low voltage amplifiers based on NGCC, a number of basic building blocks have to be developed. A new low voltage current source has been developed to increase the input common-mode range and improve CMRR. It provides large output resistance but requires very small compliance voltage. As for the output stage, two new 1.5V class AB buffers have been proposed to achieve a rail-to-rail output swing and a good control over the quiescent current. Finally, the transistor implementation of NGCC amplifier has been provided and the circuits have been fabricated to test the performance. In summary, significant contributions have been made in the theory, design and implementation of low voltage operational amplifier to improve its performance. |
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| Item Description: | Vita. "Major Subject: Electrical Engineering". |
| Physical Description: | xiv, 119 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 111-114. |