PAPER SESSION 6: SIGNAL PROCESSING
Suppression of Continuous-Time and Discrete-
Time Errors in Switch-Mode Control Loops
Risbo(1), Mikkel C. W. H°yerby(2)
(1) Texas Instruments Denmark, Lyngby, Denmark.
(2) Motorola Denmark, Denmark.
This paper presents a theoretical and experimental
study of the ability of common class-D switch-mode
control loops to suppress various errors signals. Such
errors are categorized as either of conventional continuous-
time (CT) nature, e.g., hum and thermal noise, or
as discrete-time (DT) nature being impulses at the
pulse edges, e.g., distortion due to power stage deadtime
or timing jitter. It is shown both theoretically and
experimentally that DT error suppression can be dramatically
worse than for CT errors depending on the
carrier generation/modulation mechanism used. The
theoretical modeling is based on a previously presented
discrete-time small signal model. An experimental
measurement setup is presented along with measurement
data compared to the theoretical model.