OPA656 is a broadband, unity gain stable, field-effect transistor input operational amplifier 3

Voltage feedback operational amplifiers are different from current feedback products and can use a wide range of resistance values to set their gain. In order to maintain the controlled frequency response of the non vertical voltage amplifier in Figure 1, the parallel combination of RF | RG should always be<200 Ω. In a non vertical configuration, the parallel combination of RF | RG will form a pole with parasitic input capacitance at the inversion node (including layout parasitic) of OPA656. To achieve optimal performance, the frequency of this pole should be greater than the closed-loop bandwidth of OPA656. Therefore, for the application of unity gain followers, it is recommended to short-circuit directly from the output to the reverse input.diode

Broadband and inverse gain operation

The circuit in Figure 2 shows the inverter gain of the -1 test circuit used for most typical inverter characteristics. In this case, an additional resistor RM is used to achieve the required 50 Ω input impedance for the testing equipment used in the characterization. In the circuit board environment, OPA656 is used as an inverter amplifier at the output of the previous stage, and the input impedance matching is optional.diode