LMH6629: LMH6629

It appears you are treating the first stage as a transimpedance stage - you will need to take the source capacitance and compensate for stability there with a capacitor across the feedback R. For noise reduction you should place a cap across the resistor on the V+ input. A simplified transimpedance design flow appears at the end of this article, 

https://www.planetanalog.com/author.asp?section_id=3404&doc_id=565056&

From there, you need to treat each stage as a voltage amplifier, not current - you have no Rg resistor so you are running the 2nd 2 stages at infinite gain, they will be locked at the rail with no signal path available. 

Hi Ravikumar,

there are several mistakes in your schematic. I guess you haven't worked with OPAmp so far?

Can you explain what your circuit is intended to do? What exactly is your input signal? Where does it come from?

Kai

Dear Sir,

Thanks for the reply.
I have placed a capacitor of 1pF in parallel with the feedback resistor, in each stage. Sorry, I forgot to mention in the above schematic.

Dear Sir,

Thanks for the reply.
I am trying to make a low noise current amplifier, my current signal comes from a near filed tip.
I have measured the current signal it has an amplitude of around 0.1nA - 1nA using Keithley source meter.
I have detected the signal using SR570 (@ gain 1E9) and Lock-In Amplifier (@ frequency 9.57kHz).
So I want to design an amplifier with does the job of SR570.

Well Ravi, this is a long ways from working, but starting on the first stage, that is transimpedance, the design flow is described in this presentation. On the V+ side, add some noise filtering caps on that 20kohm to ground. 

0131.Transimpedance design flow using high speed op amps.pptx

I placed capacitor in parallel with resistor on non-inverting pin but the circuit started giving sine wave output for all standard signal input.

Hello Ravi,

I think as mentioned previously need to work with one stage at a time. For your very first stage, follow the slides michael has given you. Can you provide me a schematic of the circuit you have so far. It seems the image you provided above is missing components you have added or originally had.

You can use this cookbook to design each stage of your circuit. The first stage is a transimpedance amplifier circuit. The second and third stages are voltage amplifiers. You can look at the inverting amplifier circuit in the cookbook on how to design those.
www.ti.com/.../slyy137a.pdf

Thanks!
-Karan

Dear Sir,

Thanks for reply.

The below attached is the circuit, please have a look.

Hi Ravikumar,

your circuit is incomplete. Resistors are missing:

Kai

Thanks sir for rectify me.

I'll make the changes accordingly.

Anything else, you would like to suggest/highlight in circuit?

Ravi

e2e.ti.com/.../2978851

Kai