This reference design explains the theory, design, and testing of a high-performance signal chain for DC measurements. The main target application is digital multimeters (DMMs), however the design can also be applicable to other applications, such as data acquisition (DAQ) and condition monitoring. This design achieves high DC accuracy using a high performance 24-bit analog-to-digital converter, ADS127L21, and a low-noise programmable gain amplifier, PGA855, with a typical nonlinearity of
± 2.4ppm and low drift over temperature. These devices are highly integrated, simplifying the overall signal chain design.