Signal amplification is one of the fundamental functions of operational amplifiers. Amplification allows electronics to reliably interface with the outside world. Some analog signals require a specialized amplifier. Such cases are common when dealing with temperature, pressure, and biopotentials that can be millivolt or even microvolt level signals.

A very high gain is required to condition the signal for accurate digitization by an analog-to-digital converter. The circuit is very straightforward, but choosing the correct amplifier is crucial. The amplifier needs to have ultra-low input offset and input offset drift, high common-mode and power-supply rejection, and very low noise. Depending on the signal frequency of interest, a wide gain bandwidth is necessary to achieve the desired frequency response at the required gain.

Fortunately for designers, amplifiers with the aforementioned characteristics are readily available from Texas Instruments. The TLVx886 with high dc precision and low flicker noise is an excellent choice for applications requiring very high gain for low level signals.

Use the following parameters for this design example:

• Dual supply: ±5V
• Gain: 1001V/V
• Full-scale input: ±4.5mV

The following design details and equations can be used to reconfigure this design for different output voltage ranges and current loads.