The OPA861 is a versatile monolithic component designed for wide-bandwidth systems, including high performance video, RF and IF circuitry. The OPA861 is a wideband, bipolar operational transconductance amplifier (OTA).

The OTA or voltage-controlled current source can be viewed as an ideal transistor. Like a transistor, it has three terminals—a high impedance input (base), a low-impedance input/output (emitter), and the current output (collector). The OPA861, however, is self-biased and bipolar. The output collector current is zero for a zero base-emitter voltage. AC inputs centered about zero produce an output current, which is bipolar and centered about zero. The transconductance of the OPA861 can be adjusted with an external resistor, allowing bandwidth, quiescent current, and gain trade-offs to be optimized.