DocumentCode :
2303792
Title :
Design considerations for current domain regenerative comparators
Author :
Bracey, M. ; Redman-White, W.
Author_Institution :
Southampton Univ., UK
fYear :
1994
fDate :
6-8 Jul 1994
Firstpage :
65
Lastpage :
70
Abstract :
In voltage domain applications, regenerative comparators are a common choice where high speed operation is required. Their basic structure is simple, consisting of pairs of cross coupled devices in a positive feedback or regenerative configuration. However, such structures are notoriously sensitive to offsets and hence when precise operation is required they usually form the second (or later) stage in a multi-stage comparator. The first stage, normally a differential amplifier, ensures that a large difference signal drives the regenerative stage thus giving reliable operation. In high speed sampled current domain applications, a high gain pre-amplification stage is unlikely to be appropriate, resulting in increased accuracy demands on the current driven regenerative latch. In this paper we study the performance of the regenerative comparator under current excitation. The perfectly balanced case is first considered and the performance parameters, which dictate response time for a specified differential input signal magnitude, are identified. The analysis is then repeated for the general asymmetric case and it is shown that both static and dynamic errors further limit the maximum resolution. The analytical equations derived are confirmed with SPICE simulations. Finally, a system application is presented, a sigma-delta modulator for direct digitisation of photodiode currents
Keywords :
SPICE; comparators (circuits); preamplifiers; quantisation (signal); signal processing equipment; CMOS; SPICE simulation; analytical equations; asymmetric case; current domain regenerative comparators; differential amplifier; digitisation; dynamic errors; photodiode currents; preamplification; sigma-delta modulator; static errors;
fLanguage :
English
Publisher :
iet
Conference_Titel :
Advanced A-D and D-A Conversion Techniques and their Applications, 1994. Second International Conference on
Conference_Location :
Cambridge
Print_ISBN :
0-85296-617-2
Type :
conf
DOI :
10.1049/cp:19940545
Filename :
346583
Link To Document :
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