OPA656 is a broadband, unity gain stable, field-effect transistor input operational amplifier 4

In this configuration, the output treats the feedback resistor as an additional load parallel to the 100 Ω load used for testing. Increasing the RF value to reduce output load (improve harmonic distortion) is often useful when limiting RF | RG<200 Ω parallel combinations. For the high DC precision inversion gain provided by FET input OPA656, please consider a higher gain bandwidth product OPA157.diode

Figure 2 also shows non vertical inputs directly connected to the ground. Usually, this includes the bias current to ground resistance to eliminate DC errors caused by input bias current effects. This is only useful when the input bias current matches. For JFET components like OPA656, the input bias current does not match, but it is low enough to start at (<5pA), so the DC error caused by the input bias current can be ignored. Therefore, for the conditions of the inverter signal path, it is not recommended to use resistors at non rotating inputs.diode

Broadband, high sensitivity, transient design

The high GBP and low input voltage and current noise of OPA656 make it an ideal broadband transient amplifier with low to moderate transient gain. Higher transient gains (>100k Ω) will benefit from the low input noise current of FET input operational amplifiers such as OPA656. The homepage of the data table displays a transient design example. The design of large-area detectors requiring high bandwidth will benefit from the low input voltage noise of OPA656. This input voltage noise diode source capacitance causes it to reach its peak in frequency, and in many cases, it can become a limiting factor for input sensitivity. The key elements of the design are the expected diode capacitance (CD) with reverse bias voltage (- VB) applied, the required transient gain, RF, and GBP of OPA656 (230MHz). Figure 3 shows a design using a 25pF source capacitor diode with a transient gain of 50k Ω. When setting these three variables (including adding the parasitic input capacitance of OPA656 to CD), the feedback capacitance value (CF) can be set to control the frequency response.diode