SBOS622A July 2018 – October 2018 OPA855
The OPA855 can be configured with single-sided supplies or split-supplies as shown in Figure 58. Split-supply operation using balanced supplies with the input common-mode set to ground eases lab testing because most signal generators, network analyzers, spectrum analyzers, and other lab equipment typically reference inputs and outputs to ground. Split-supply operation is preferred in systems where the signals swing around ground. However, the system requires two supply rails. In split-supply operation, the thermal pad must be connected to the negative supply.
Newer systems use a single power supply to improve efficiency and reduce the cost of the extra power supply. The OPA855 can be used with a single positive supply (negative supply at ground) with no change in performance if the input common-mode and output swing are biased within the linear operation of the device. In single-supply operation, level shift the dc input and output reference voltages by half the difference between the power supply rails. This configuration maintains the input common-mode and output load reference at midsupply. To eliminate gain errors, the source driving the reference input common-mode voltage must have low output impedance across the frequency range of interest . In this case, the thermal pad must be connected to ground.