Suggestion for Amplifier for Sound Level Meter

Hi Shai,
This is a difficult question to answer without more information about the customer's system. What is a typical signal level at the input? What is the intended output - driving an ADC, or just an analog output? What is the intended frequency range? Does this system need to have a logarithmic response in the analog domain, or will that be handled by a DSP?

Hi Shai,

as Alexander already mentioned, this is a very complex issue. You need an amplifier for a condenser microphone? You need one or more weighting filter? You need a peak rectifier and a quasi-peak rectifier with well defined time constants?

Do you have any schematic?

Kai

Hello team,

Sorry for the slow response, I was out of the office.
In fact, the application is very simple so there is no need for complicated algorithmic or use of DSP.
The purpose of the application is to identify the volume of the environment, and by a certain threshold (of the dB) the system sends an interrupt signal to the main MCU.
Do you have any suggestions, thanks in advance?

Kind regards,
Shai

Hi Shai,
If you're using an electret microphone element as your microphone, I'd suggest the circuit described in www.ti.com/.../tidu765.pdf as a starting point. From there, there are a couple of approaches you could take:
1. Use an analog peak detector to capture the peak value of the audio waveform. Feed this peak into a comparator to generate the interrupt signal. If a latching interrupt isn't required, you might not need the peak detector, so long as short pulses can still reliably generate the interrupt.
2. If a latching interrupt is required, you could feed the output from the amplifier into a comparator, then use an S/R latch to hold the interrupt signal until your ISR can handle it.