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One of many useful circuits that you can create using an operational amplifier (op amp) and resistor network is a difference amplifier (DA). DAs allow you to measure the difference between two signals, which is useful for current and voltage sensing in systems such as solar panels, power banks and other DC/DC modules. Furthermore, many DAs can apply gain, add a reference voltage to the signal, and reduce common-mode noise from input signals.

There are two main types of DAs: discrete (with external resistors) and integrated (with monolithic or on-die resistors). In this article, we’ll use measured data (offset voltage, common-mode rejection ratio [CMRR], gain error and gain error drift over temperature) to compare discrete and integrated DAs.