Operational Amplifiers (Op Amps)

Information to aid in the selection of op amps for optimum noise performance, in both graphical and tabular form. This document covers new low noise op amps as well as some high speed op amps. Although a great deal has changed in eight years, especially in electronics, noise is still a critical issue in op amp circuit design and the LT®1028 is still the lowest noise op amp for low source impedance applications.

The new LT®6202 Op amp combines 100MHz gain-bandwidth, 1.9nV/√Hz voltage noise and rail-to-rail inputs and outputs, while consuming only 2.5mA. It also features a low 0.75pA/√Hz current noise, and it contributes exceptionally low total noise and distortion power in small-signal applications. The device is fully specified on 5V, 3V and ±5V supplies and is available in industrial and commercial temperature grades in both the SO and SOT packages. Quad and dual versions are also available as the LT6204 and LT6203, respectively.

Conventional monolithic micropower operational amplifiers with a wide supply voltage range require a large die area and therefore, a large package and footprint. The unconventional LT®6011 dual operational amplifier fits 25µV input precision micropower operation and wide 2.7V to 36V supply range in a tiny new package - its 3mm x 3mm DFN package is so small it doesn’t even have leads. The LT6011 also provides rail-to-rail output swing and utilizes superbeta input transistors to achieve picoampere input currents.

The Microchip Technology Inc. MCP6031/2/3/4 family of op amps operate with a single supply voltage as low as 1.8V, while drawing ultra low quiescent current per amplifier. This family also has low input offset voltage and rail-to-rail input and output operation.

Op amps are as prolific in analog circuits as salt and pepper is on food. They are sprinkled throughout the sensor data acquisition system, performing a variety of functions.