Can someone point me to information on this?
The PGA on the ADuCM360 is only capable of handling signals of <=100Hz.
This PGA is not suitable for measuring your 488Hz signal
We have no explicit value for this, but this is not related to the problem you asked about in the other thread.
Remember the ADC-Modulator is sampling single bits at a speed of 125ksps.
The PGA, Buffer, etc. are all designed to support this.
The settling you may experience and differences in settling time are pure digital filter effects influenced by ADCxFLT bits.
OK, thanks. That makes sense for normal sampling. But remember that I am trying to do synchronous detection of an LED signal pulsed at 488Hz. I usually want the amplifier to have bandwidth at least 10X higher than the signal frequency so that the square waveform is preserved. So at the highest PGA gain of 128, that would mean the PGA gain*bandwidth needs to be ~488Hz*10*128 = 620Khz. I am wondering if the PGA has this gain*bandwidth - my tests seem to indicate that it does not.
This was only for future reference; I don't need a high PGA gain for what I'm doing now. But if it is possible to get a number for the PGA gain*bandwidth it would be useful to know it.
I will ask our internal test engineers if we have specific data for this available, but expect it is not that high as 620kHz - but wait till I come back with an answer.
Thanks. Only <= 100 Hz even at low gain? It seems to work OK with PGA gain=2.
For a gain of 1 (by-passing the PGA) there is no limitation other than the sampling speed - so if you need gain, it is recommended you use internally gain of 1 and an external gain-stage which provides the required amplifying.
It may work also with the internal PGA, but not guaranteed,
Hi, we are using the eval board for the aducm360/361 and a simple test (signal generator -> adc in -> dac out -> oszilloscope, based on the adcmeter.c sample code) with gain 1,4,8,16,32 did not show a 100Hz bandwidth limit as mentioned in this thread. Are we just lucky? Any idea why this limit not mentioned in the datasheet/reference?
Thanks for your help
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