A low noise laboratory-grade measurement preamplifier

No lab or hobby shack should be without a preamplifier to measure very low signals with very low noise, defined gain and wide bandwidth. Samuel Groner's latest creation has 0.4nV/RtHz and a bandwidth extending to 1Mhz with low impedance sources. Gain is 60dB (1000x). This article documents the full design path, from the design brief, through topology considerations, device selection and design tradeoffs, and concludes with a final design complete with PCB layout. The specific discussion on low noise design is of interest even if you don't want to build this preamp.