OPA2365-Q1: Recommended feedback resistance

Would need the desired gain , loading and whether inverting or non-inverting. Intended schematic would help

Hi Michael,

The desired gain is around 2. Input is a sinusoid of 1.076 Vpk and output desired is 2.052 Vpk. Can we use the feedback resistor in the 1kohm range for OPA2365 or higher than 10kohm is recommended?

Thank you in advance.

Non-inverting or inverting, what supplies and max frequency 

How are you going to center up the output swing and/or stay out of clipping. 

Please find the circuit configuration. Vin is a sinusoidal differential input of +/-1.076V, 2kHz. A level shift of 2.5V is added to match the ADC range. 5V supply voltage is given to the OpAmp. According to the transfer function, the ratio of R3707 to R3704 is around 2. What is the recommended range for R3707 feedback resistance.

Thank you.

Your file or picture did not come through, you need to insert those using the paperclip symbol at the top ribbon, 

Please find the circuit below and the specifications as mentioned earlier. Can you please let me know the range of feedback resistor value, as it isn't mentioned in the datasheet.

Thank you in advance.

This zero crossover device (which you do not need in your app) has a fairly high input capacitance. It would be better to use 1kohm feedback (500ohm input) resistor to keep the effect of the feedback pole out of the LG phase margin. 

Hi Rupali,

what exactly (in terms of R, L, C) is connected to the output of your differential amplifier? And what exactly is driving the inputs?

Kai

Hi Michael,

Why do you say we don't need this OpAmp in our application?

Hi Kai,

The output of the amplifier is going to the ADC after a RC filter of 1k, 4.7nF. The input is the output of another Isolated Amplifier, that amplifies a sinusoidal voltage signal.

Rupali

Hi Rupali,

I ask myself why you want to take such a fast OPAMP, if you have a charge kick back filter (1k / 4n7) with a corner frequency of

1Hz / 2 / pi / 1k / 4n7 = 34kHz

at its output. In this case a somewhat slower OPAmp would suffice.

Another issue is the input impedance of this circuit. This mainly depends on the isolation amplifier and how much current it can drive. What isolation amplifier are you using?

Kai

Hi Kai,

We will look into the requirement for high-speed OpAmp. And we are using AMC1301 isolation amplifier at the input side.

Rupali

Thanks Kai.