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How to measure slew rate(SR) for fully differential OTA?

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gunpla

gunpla

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Dear All:

i would like to measure the slew rate(SR) and slew rate output(SRO)

for fully differential OTA.

i search the three method of measured evnironment

if these method mistake

can someone tell me measured scheme or upload the schematic?

thanks!


42_1172991136.jpg
 

I think the second method can be used but u have to add ur load capacitance at the output of the OTA
 

The third methode is wrong because of the input RC delay and integrative configuration.
The first and the second methode does not measure the real slew rate of the fully differential output, the slew rate will be different for inverting input (image 2) versus noninverting input configuration (image 1).
However any of the measuremet schemes 1 or 2 will gave you an approximative value of the slew rate. If you need a precise one, use a fully differential generator and measure the differential output value with a dual channel scope.
 

maybe these methods are all feasible, i don't know. hope intelligent answers
 

Using the first method and add the Rload & Cload.
Give it a VPLUS voltage (from 0~vdd).
And you will see the output will follow the input with a slop.
The 10% to 90% slop is you SR.[/img]
 

I'd go with the second, but make sure you very large resistors so that it doesn't affect the output current.

First is also fine, as seanyang described.
 

seanyang said:
Using the first method and add the Rload & Cload.

==> should both output ends add with Rload and Cload? I mean should the feedback node be loaded with R and C? This node is for feedback only!
Click to expand...
 

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