Other Parts Discussed in Thread: OPA2188
Hello,
Our customer want to see OPA2188's closed-loop gain and frequency graph . Really, it was not found in the datasheet.
Could you provide this graph ?
And, with my understanding, closed loop gain and phase performance are shown in few products, almost all OPAmp datasheet show only open-loop gain and frequency performance.
Is it difficult to measure closed-loop performance ?
Thanks and best regards,
Hiroshi Sato
Hiroshi,
Only open-loop gain (AOL) is shown in the product data sheets (PDS) because closed-loop gain is a function of the customer specific circuit configuration. However, closed-loop may be easily seen by looking at the graph of open-loop gain and extrapolating the closed-loop gain into the point of intersection with AOL - see simulation plots below. Thus, for example for closed-loop gain of 10 (20dB) the -3dB bandwidth is 200kHz while for a closed-loop gain of 1000 (60dB) the -3dB bandwidth is 2kHz, etc. Take a look at the -3dB frequency point to determine the phase margin for your specific closed-loop gain and capacitive load conditions - see attached schematic for your own simulations: closed-loop gain=Vout/Vin while AOL=Vout/Vos.
