Gain Bandwidth at high frequency

[Amr Wael]

Hello,
I Have a simple question regarding the open loop gain of an opAmp. It has a voltage gain VS Frequency graph in which the gain is 6 dB only at frequency of 10 MHz. is this the open loop gain of the opAmp? does this mean it can't function in a closed loop configuration at this frequency due to the low open loop gain?
Here is the data sheet , the graph I am talking about is on page 6.

https://www.analog.com/media/en/technical-documentation/data-sheets/LT1007-LT1037.pdf

 

[stenzer]

Hi,

I assume you are referring to the LT1037 in the graph shown in the upper right of page 6. For me it looks like a gain of about 10 dB @ 10MHz. The closed loop gain is "bounded" by the gain bandwidth product (GWB = Bandwidth • Gain), stated on page 3. For a gain of ~13 dB (= 4.4668) @ 10 MHz the GWB would be 44.668 MHz, which corresponds to the minimum GWB. Note, the GWB is determined with the cutoff frequency.

BR

 

[danadakk]

Gain error would be high at 10 Mhz because the Aol(10Mhz) is so low.

**broken link removed**

**broken link removed**

https://www.ti.com/lit/an/slyt383/slyt383.pdf?ts=1617183307705&ref_url=https%253A%252F%252Fwww.google.com%252F

https://www.renesas.com/us/en/document/oth/r13an0001-closed-loop-gain-error?language=en

Regards, Dana.

 

[KlausST]

Hi,

The usual way is to first decide which gain, bandwidth one needs in a circuit. Then choose the Opamp.

Klaus

 

[danadakk]

From the Renesas Ap Note this is the most revealing I think, gain error vs frequency -

Regards, Dana.