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ADS8665: ADS8665

Part Number: ADS8665
Other Parts Discussed in Thread: ADS8661, ADS8556, ADS8557, ADS8558, ADS8568, ADS8548, ADS8528, THS4561, OPA192

Hi 2 all! Maybe my question is fool byt i need answer. I looking for ADC for sampling 50kHz bipolar signal. My choise is ADS8661 with 1Msps but... after PGA it has 15 kHz LPF. I am Sorry but why?

Best regards Andrii, sorry for my English)

  • Hi Andrii,

    The LPF that follows the PGA is helpful in filtering out noise from the front-end circuit especially 1Mohm input resistance, this structure allows the ADC to maintain a good performance. Since your input signal frequency is high (50kHz), there are two solutions which can be used:

    1. If you need multi-channel inputs:  High voltage ADC without LPF is a good option,for example: ADS8528(12-bit/8-ch),ADS8548(14-bit/8-ch) and ADS8568(16-bit/8-ch), or ADS8558(12-bit/6-ch),ADS8557(14-bit/6-ch) and ADS8556/8555(16-bit/6-ch). They can accept high voltage direct bipolar signal up to +/-12V.

    2. Attenuator amplifier+low voltage ADC solution: below is a good reference design to show an example:  OPA192+THS4561/4551+ADS89xx/ADS91xx ADCs