TLV9062：BOM List of two-wire microphone circuit

Hi Jeff,

this circuit only satisfies lowest quality demands. If you fully read this appnote, you will see that the best you can achieve with this circuit is a THD+N of -52dB which translates to a distortion plus noise of 0.25% of signal. This is very poor. 

There's another disadvantage of this circuit. The decoupling cap C2 which is necessary for stability forms a low pass filter and causes a drop of frequency response at the higher audio frequencies: With increasing frequency the signal current is no longer flowing through R3 but is more and more absorbed by C2. This frequency drop has to be compensated by a gain which increases with frequency. This is accomplished by C7 which causes an increase of load current with increasing frequency. But a single C7 would destabilize the OPAmp and for guaranteeing stability the isolation resistor R9 must be mounted in series to C7. Unfortunately, this isolation resistor makes it impossible to fully compensate for the drop in frequency response caused by C2. So, as a result, the frequency response of this circuit will be very limited and will show a very early drop. I guess the frequency response of this circuit will not be much wider than the telephone frequency range of 300H...3kHz.

Compared to a standard three-wire microphone amplifier circuit the performance of this two-wire microphone amplifier circuit is very limited and shows noise, distortion, gain linearity and stability issues.

Kai

Hi Jeff,

Let me take a look into which component values were chosen for their testing. 

Best Regards,

Robert Clifton 

Can you recommend a two-wire Microphone amplifier circuit with a bandwidth of 50HZ~16KHZ +-1dB? (Mic Bias 8V/680ohm)

thanks!