When choosing an operational amplifier for an application you already know you will be looking at criteria such as supply rail, slew rate, drift, output voltage swing, gain bandwidth, residual current, noise, etc., your final choice will often be a compromise. It goes without saying we will only be considering small signals so when the application calls for high output voltage and current drive something special is required. Apex Microtechnology specializes in the design of add-on power boosters to provide a two-stage solution to the problem.


 
The range of booster stages from Apex can be used to provide the necessary power boost and are connected in series with conventional opamps as shown in the example illustrated circuit. The first opamp stage takes care of the (high) small signal gain while the booster stage supplies the required output level and current. The feedback is provided over both ICs. The booster stage is a hybrid circuit consisting of passive SMD components integrated along with power semiconductors on a common ceramic carrier where a heat sink can be attached when necessary. The complete family of boosters offers a good specification range and package outlines. The PB51A model, for example, provides currents up to 2 A at a voltage swing of ± 150 V.