Anybody have any idea how accurate a sigma-delta A/D you can build using the 
comparator in the PIC?

Bob Ammerman
RAm Systems

----- Original Message ----- 
From: "Harold Hallikainen" <harold@hallikainen.com>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Sunday, May 15, 2005 3:36 PM
Subject: Re: [EE] Comments on circuit


> Seems complicated to me! I'd be concerned about the stability of the
> differential amplifier (if you're trying to build the diff amp yourself),
> stability of the PWM output, ripple of the PWM output, etc. IF the
> transducer indeed has the resolution and accuracy you're seeking, it seems
> a simpler approach is to use an external A/D that has more resolution. I
> did a precision thermometer using a Data Acquisition System chip from
> Maxim. It, as I recall, has a 16 bit delta sigma A/D, a 10 bit D/A, and a
> real time clock. Simple to interface to the PIC with SPI.
>
> Harold
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