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Hi all,
PSOC 5 has an IDAC with 8MSPS. In my application, I required sinewave up 160kHz. Can I pass the output of IDAC to an trans-impedance amplifier so that I get sinewave in voltage format?
Thanks
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PSoC 5LP
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I do not see any reason why you may not do that.
Btw: There is a WaveDAC component availlable that uses the IDAC. Have a look at the Datasheet www.cypress.com/. Will simplify some things.
Bob
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Some considerations -
1) TIA may have be offset to handle fact it is inverting. Or change
polarity of IDAC.
2) TIA conversion R tolerance is 60%, you will have to factor that in
to determining amplitude range you will get.
3) You need to calc slew rate needed for 160 Khz and pk-pk range
you want. The basic PSOC OpAmp (used in TIA) ranges from .9 to
3 V/uS. www.radio-electronics.com/info/circuits/opamp_basics/operational-amplifier-slew-rate.php
4) You have to manage compliance range of IDAC in your calculations.
5) Consider terminating IDAC with a low R like a K or so, then buffering
that pin with an OpAmp.
6) At 160 Khz, N samples/period, your table lookup loop has to run at
N x 160 Khz, just a consideration.
Regards, Dana.
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Hi Thanks all for your swift response.
Appreciated
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If you want a 1V sine pk-pk at 160 Khz, 32 samples, you will see you can't
do it with WaveDAC8 because of settling time of VDAC. In fact you either have
to drop Fsamp by ~ 5 or the # samples by ~ 5, translate lots of distortion. And you are
right up against the slew rate of the OpAmp in WaveDAC8. In fact if you terminate
the IDAC externally with a low Z R (to get fast setltling time) you still have to go thru
OpAmp to buffer, or live with terminating R as your output Z for the sine gen.
Do the calculations.
Regards, Dana.
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Hi Dana,
Many thanks to your reply.
Do you think the following will work.
Instead of using the internal components of PSOC 5 to buffer, can I used external components, including resistor and high speed trans-impedance amplifier to perform the current to voltage conversion?
Thanks.