Frequency Response of Generalized Sampled-data Hold
Functions
Julio H. Braslavsky, Rick H. Middleton and Jim S.
Freudenberg
Abstract
Alternatives to the traditional Zero Order Hold known as
Generalized Sampled-data Hold Functions have been proposed by
several authors. More recently, it has been noticed that these new
holds incur intersample behavior penalties in many cases. In
studying such behavior, one of the issues of relevance is the
``frequency response'' of the hold. For example, it is known that
``non-minimum phase'' zeros of the hold impose design tradeoffs in
the continuous-time response to disturbances of the sampled-data
system. In this paper, we go deeper into the analysis of the
frequency response of this devices, and provide some preliminary
results on zero location and integral constraints satisfied by the
hold. One of the key results of this paper is to show a number of
circumstances in which non-minimum phase hold responses may occur.
We also show that asymmetric holds have zero locations off the
jw-axis, and therefore, tend to have poor frequency responses,
which will deteriorate sensitivity and robustness properties of the
sampled-data system.
Keywords: Sampled data systems, Digital-analog
conversion, Frequency response, Generalized sampled-data hold
functions.
21 pages
34 references
82 Kb
