What is the MAX41400 input impedance for differential and common? I don't believe it's listed but its a very important parameter for my uses
MAX41400
Recommended for New Designs
The MAX41400 is a low-power, high-precision instrumentation amplifier with programmable gain through input pins.
Available in a space-saving, 9-bump wafer...
Datasheet
MAX41400 on Analog.com
AD8237
Recommended for New Designs
The AD8237 is a micropower, zero drift, rail-to-rail input and output instrumentation amplifier. The relative match of two resistors sets any gain from...
Datasheet
AD8237 on Analog.com
AD8235
Production
The AD8235 is the smallest and lowest power instrumentation
amplifier in the industry. It is available in a 1.5 mm × 2.2 mm
wafer level chip scale package...
Datasheet
AD8235 on Analog.com
What is the MAX41400 input impedance for differential and common? I don't believe it's listed but its a very important parameter for my uses
GLADION - Moved from Amplifiers to Instrumentation Amplifiers. Post date updated from Wednesday, March 27, 2024 8:44 PM UTC to Monday, April 1, 2024 1:10 AM UTC to reflect the move.
Hi Mgibson9
Thank you for reaching out and sharing your inquiries with the team.
Regarding the CM and Differential Input impedance of MAX41400, no data is available on the datasheet EC spec table.
Though navigating with the TPC plots, we can use useful information on page 9 (toc05) to estimate the input impedance. https://www.analog.com/media/en/technical-documentation/data-sheets/MAX41400.pdf
I can’t find any similar related plots for IB vs Differential -Voltage; we can look further, and my colleague will get back to you.
Utilizing the VDD = 3.6V information, as the graph has a linear portion.
We can use two points from the linear part of the graph: Point 1 and Point 2.
The ratio of Zcm = Delta VCM / Delta IBias:
Computing for Zcm = (2-1) / (-40pA + 225pA) = 5.4054Gohms
I hope this initial data will help you.
Regards,
Thanks a lot Arsol! This may be sufficient actually. Also i used for differential Z this equation: Zdiff = (input offset voltage / input bias current) * max gain
Zdiff = (1uV / 10pA) * 200 V/V = 20MOhm. This actually seems to work for other amplifiers like AD8237 and the AD8235, where each of these metrics are available to confirm.
This may be a 'janky' method, but yours is sound haha.
Thanks!
Matt
Hi Mgibson9
Thank you for confirming that our recommendation meets your requirements.
We will close this thread if you have no other inquiries. If you have a new inquiry regarding the same topic, you can submit a related question.
Regards,