Accurate Peak Detector

Hi Shimon,

Can you share with us some specifications such as:

• Bandwidth
• Supply voltage range
• minimum offset voltage
• Circuit design

Knowing these things will help us get a better starting point. 

Best Regards,

Robert Clifton 

Hi Robert,

The problem I'm trying to solve is almost identical to what is described here - https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/940064/how-to-improve-the-accuracy-of-peak-detector-as-high-as-posssible

I cannot use the solution as is since I have only one supply (3.3V, may change to 5V if absolutely necessary) and the entire solution must be under $1 in BOM. I'm sure those two limitations will yield poorer performance, but would like to know if there is a way to estimate how poor. And, hope to get a recommendation on a lower cost op amp that will best fit.

Assuming a circuit running on 3.3V supply, the pulses (input signal) voltage range is ~0.5V to 3V, the maximum pulses rate is ~2Mpulses/sec and minimum rise/fall time is ~200ns

Thanks,

Shimon 

Hi Robert,

Thanks. This very helpful. I'll use it as a starting point and optimize from there.

What is the purpose of the 50 Ohm resistors?

Thanks,

Shimon 

Hi Shimon,

I usually recommend having an external resistor between the output of one op amp and the non-inverting input of another to act like an external current limiter. 

In this schematic, I'm not entirely sure why the user originally put the 50ohm resistors in the schematic. Especially the one in the first stage feedback. 

I also did forget to put the 20ohm resistor that was in the original schematic. 

Best Regards,

Robert Clifton