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reference buffer for SAR A/D ? (Read 3205 times)
Ajay
Junior Member
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Posts: 14
Asia
reference buffer for SAR A/D ?
Apr 30
th
, 2012, 12:55pm
I have a SAR A/D converter and I need to make a reference buffer for it. The buffer has a big capacitor of a few micro-Farad connected to it. This acts a voltage source for the capacitive DAC array. What type of an op-amp architecture do I use for the buffer ? A 2 stage miller compensated opamp may not be suitable since the compensation cap. will be in pico-farad only. Any ideas / suggestions will be appreciated. Thanks.
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carlgrace
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Berkeley, CA
Re: reference buffer for SAR A/D ?
Reply #1 -
May 11
th
, 2012, 1:25pm
Single-stage op amps get more stable as you increase the load capacitor. Since you have such a large cap, maybe you should look into a single-stage op amp buffer.
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pixel
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Re: reference buffer for SAR A/D ?
Reply #2 -
May 18
th
, 2012, 3:00am
In this case type of the output stage and buffer speed are specially important.
What is the resolution clock frequency and total DAC capacitance of your ADC?
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loose-electron
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San Diego California
Re: reference buffer for SAR A/D ?
Reply #3 -
May 24
th
, 2012, 1:30pm
you are driving a capacitive load.
OTA with a push pull output.
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Jerry Twomey
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