What is the meaning of gain 7V/V in OPA 855

[joniengr]

Hi,

The gain of the Operational Amplifier in inverting configuration is Vout / Vin = - Rf / Ri.

Usually the voltage gain is represented in dB after taking Log. I am looking at the datasheet of OPA 855 which has gain 7 V/V. Does it mean that the gain of this Operational Amplifier is 7 ?

8 GHz gain-bandwidth means that this Operational Amplifier has unity gain up to 8 GHz, right ?

 

[barry]

1) You need to read ALL the words.
2) It says 7V/V STABLE. That means it’s not stable with lower gains.
2) GBW PRODUCT specifies the maximum allowable gain at a particular frequency (or maximum frequency for a particular gain]. It does not necessarily mean you can have a gain of 1 at 8GHz. See (2).

 

[FvM]

Reading the very first datasheet lines answers your question.

The special meaning of gain = 7 is minimal stable gain. OPA855 is a decompensated, not unity stable OP. Respectively unity gain of 8MHz isn't feasible. Many curves and waveforms are illustrating the parts behaviour.