Lockin amplifier, phase modulation signal filtering

I need to make an amplifier which could amplify very small signals (uV) embedded in noise. The frequency of the signal to be amplified is known. The problem is that the signal has too much noise around it. I was told that a lock-in amplifier or Phase sensitive detection (demodulation) can solve the problem but i don't know how to make it. Please help :-|

Hi,

I know nothing about Lock-In Amplifiers, so a quick search came up with plenty of information. The simplest description said: "Lock-in amplifiers are used to detect and measure very small AC signals" ...Looks like, after viewing a block diagram of the circuit: if you have plenty of experience with circuits/are an engineer, making one will be quite a straightforward task, otherwise, if you are like me, figuring out how to buy one ready-made, second-hand perhaps, would be the most sensible course of action concerning time and effort, unless the goal is educational and a personal challenge.

Having said that, looking at the price of manufactured ones... it certainly doesn't hurt as much to read a while and see how feasible putting one together yourself is.

What is a Lock-in Amplifier?

About Lock-In Amplifiers

Lock - in Amplifier and Applications

**broken link removed**

The above came from: lock-in amplifier search term in Google search engine, there are other interesting-looking documents there.

Hi,

First:
Filter away all unwanted frequencies.

Then: decide if you have a fixed and known phase angle between your reference signal and the input signal.
If yes, then you just need a controlled rectifier.
If no, then you need a complete lock in amplifier.

In another thread I posted and discussed a curcuit.

Klaus

What do you mean with "I need to make"?

You need it for laboratory purposes or a fully-integrated solution?

In any case, I would take a glance to this: https://sites.google.com/site/lockinamplifiers/

It is a good book which covers all the aspects of the operation of Lock-In Amplifiers.