Electret Capsule Micro-Phone Pre-Amplifier Using TLV6741 Op-Amp

I am here with one more electret microphone preamplifier. This circuit uses an op-amp in a trans-impedance amplifier configuration to convert the output current from an electret capsule microphone into an output voltage. The common mode voltage of this circuit is Constant and set to mid-supply eliminating any input–stage cross over distortion, Circuit and description of the project from Texas Instruments Application. The circuit is based on TLV6741 Op-Amp from Texas Instruments.


  • Supply 5V DC
  • Input Pressure 100dB SPL(2Pa)
  • Output Voltage 1.228V
  • Frequency Response Deviation @20Hz>-0.5dB,@20Khz>-0.1dB

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Microphone Parameter

  • Sensitivity @94dB SPL (1Pa) >>-35+/-4dBV
  • Current Consumption (Max)>>0.5mA
  • Impedance>> 2.2KOhms
  • Standard Operating Voltage 2V

Op-Amp TLV6741

The TLV6741 operational amplifier (op-amp) is a general-purpose CMOS op-amp that provides low noise of 3.7 nV/√Hz and a wide bandwidth of 10 MHz. The low noise and wide bandwidth make the TLV6741 device attractive for a variety of precision applications that require a good balance between cost and performance. Additionally, the input bias current of the TLV6741 supports applications with high source impedance. The robust design of the TLV6741 provides ease-of-use to the circuit designer due to its unity-gain stability, integrated RFI/EMI rejection filter, no phase reversal in overdrive conditions and high electrostatic discharge (ESD) protection (1-kV HBM). Additionally, the resistive open-loop output impedance makes it easy to stabilize with much higher capacitive loads. This op-amp is optimized for low-voltage operation as low as 2.25 V (±1.125 V) and up to 5.5 V (±2.75 V), and is specified over the temperature range of –40°C to +125°C. The single-channel TLV6741 is available in a small size SC70-5 package.