LF356: lf356 gain problem

Part Number: LF356

Hi, i am using lf356m to design an amplifier, but i find that when the frequency is low, such as 10, 20 or 50Hz,the gain is much smaller than i hoped, the sch and gain response is like below, the x axial is frequency , the y axial is gain number. please  help to find out the response, thank you.i hope that the gain is same no matter the frequency low or high.

User,

Let's Start with the simple poles and zeros
Input zero is 1/(2pi*C4*R5) = 1.6 Hz, so it will be flat above 16 Hz
Gain pole is 1/(2pi*C1*R1) = 1.6 kHz, so it will be flat below 160Hz

Because both R5 and R3 tap the same 1/2 VCC supply then interaction across frequency will be complicated.
Notice that R3 < R2||R4 so the voltage divider resistors are a significant part of the inverting ground resistance.

Do you want the same gain for the DC component of your input signal? If not what is the desired low frequency cutoff?
What is the maximum input frequency? What is the maximum output amplitude (so I know how much slew rate is needed)

Hi Ronald,

Thanks a lot for your help, i have changed the circuit as below, and gain works good now,

I don't want to amplify the DC component of the input signal, i want the low frequency cutoff is 5Hz, the high frequency cutoff is 2000Hz,

what i need to do to realize the above two cutoff?

the maximu output amplitude is less 1V.

Thanks again.

Michael Ding.