Other Parts Discussed in Thread: THS4541
Hi Team,
My customer is looking for some guidelines for input driving circuit for ADS52J90 ADC. They are planning to use it in 8-channel mode. The ADC is driven by an amplifier and we understand following datasheet specs regarding common-mode and input swing. Input common-mode voltage range is between 0.7 to 0.9V with typical being 0.8V. The peak input swing is required to be limited between -0.3V of VSS and 0.3V of 1.8V supply, i.e. 2.1V in our case. We understand that the ADC linear input swing is 2Vpp with each differential input swinging between VCM-0.5 to VCM+0.5.
We found input driving circuits for ADC (shown below), one in the datasheet and another similar one in the EVM document. Please let us know the recommended input circuit. We plan to drive the ADC with THS4541 with 40% attenuation to limit the input voltage swing within the recommended operating conditions of the ADC. Could you also let us know the impedance seen looking into the ADC analog inputs in the 8-ch 200MSPS mode as that will have an impact on the choice of resistances for the attenuation? An example circuit of what there are conceiving is shown using 120Ω/200Ω (differential) resistance network for the voltage.
Circuit from Datasheet:
Planned input circuit (The ground between R17 and R18 will be changed to Vcm with a 1uF filtering cap to ground as shown above):
Thanks,
Mitchell
