SBOSA87A December 2021 – November 2022 LMH5485-SEP
PRODUCTION DATA
In many ways, this method is a much simpler way to operate the FDA from a design equations perspective. Assuming the two sides of the circuit are balanced with equal Rf and Rg elements, the differential input impedance is the sum of the two Rg elements to a differential inverting summing junction. In these designs, the input common-mode voltage at the summing junctions does not move with the signal, but must be DC biased in the allowable range for the input pins with consideration given to the voltage headroom required from each supply. Slightly different considerations apply to AC- or DC-coupled, differential-in to differential-out designs, as described in the following sections.