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Design >> Analog Design >> dead-zones in delta-sigma modulators (first order)
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Message started by tul84 on Sep 21^st, 2015, 7:02am

Title: dead-zones in delta-sigma modulators (first order)
Post by tul84 on Sep 21^st, 2015, 7:02am

Hi,

can somebody give an explanation on dead-zones in delta-sigma
modulators. Can this effect be seen in simulation?

Title: Re: dead-zones in delta-sigma modulators (first order)
Post by sheldon on Sep 23^rd, 2015, 9:23pm

There is a detailed discussion in "Understanding Delta-Sigma Data Converters" see Idle Tone Generation, page 42. The problem can
be seen in simulation.

Title: Re: dead-zones in delta-sigma modulators (first order)
Post by saqibshah on Oct 8^th, 2015, 5:53am

Dead zones are a result of finite opamp gain gain in Sigma Delta Modulators. The reason that dead zones occur is because the opamp is not able to completely transfer the charge from the sampling capacitor to the integrating capacitor.

The effect of dead zones actuially results in a certain "minimum" input being present at the Modulator before it can generate a LSB so as to say. Roughly, a gain of 1/LSB(in volts) is necessary to avoid the Dead zone effect.

The post about recommends reading through the Temes book, which is an excellent source for understanding dead zones.