I want to built a lock-in amplifier with a LO frequency below 5kHz. I am little confused about the choice between AD630 and ADA2200. The performance is the main concern in my application (not the power consumption nor the price). How can I choose the best part: what are the main specifications to look at? And what would be better as a preamplifier: a low noise transimpedance amplifier (such as AD8067, ...) or an input amplifier (such as ADA8429, ...)?
Thank you very much for your answer.
Thanks for the email. The AD630 performs as a synchronous detector and was designed as a LF averaging detector. When I see the term LO I associate it with a PLL. The AD630 isn't a PLL, if that is what you need. The original targeted application was to extract very-low amplitude directional information from LVDTs and performs very well at that. However there is no phase detector or I and Q detection and so does not emulate a true PLL.
I'm not an expert on the ADA2200, and I know of no comparison studies between the 2 parts. Contact Brian Harrington
for further info on ADA2200.
There is a third option that may provide the best performance. That is the LTC6943. If you look on page 10, there is a schematic for a lock-in amplifier. This circuit may perform the other 2. It is hard to say. One key metric of performance for a lock-in amplifier is the integrated noise over its output bandwidth. But there are other metrics. They need to be considered in the context of the application.