Instrumentation Amplifier
Like the Differential Amplifier, the Instrumentation OP-Amp configuration has two inputs, one inverting and one non-inverting. And like the Differential Amplifier, signal that is common to both inputs is largely ignored, while a difference in signals is amplified. This amplifier differs from the Differential Amplifier in that it has a much higher input impedance and, usually, much wider bandwidth. In addition, it requires at least three OP Amps; whereas, the Differential Amplifier only requires one. Furthermore, figuring out the values for all its resistors much more difficult by hand.

Inverting Amplifier
The Inverting Amplifier configuration inverts the input signal so that it is returned 180° out of phase. This the preferred configuration for an OP Amp amplifier. The rule is Whenever possible--invert. The advantage of this configuration lies in the that the signal enters the amplifier at a zero voltage, zero impedance point, the conjuncture of the two resistors and the inverting input. This means that unlike the Non-Inverting amplifier configuration which accepts the full voltage swing of the input signal, which can cause non-linear effects because of the moving of the input bias voltages and compressing of voltage headroom as the signal swings from one extreme to the other, the Non-Inverting amplifier inputs are comfortably at the same power supply midpoint. Also, unlike the Non-Inverting amplifier, the gain of this amplifier can be set to less than unity, unity, or greater than unity. Audio Gadgets helps in design of this circuit by showing the effect of component changes or, in the case of specifying a desired gain, the component values needed.

Non-Inverting Amplifier
The Non-Inverting amplifier configuration is the standard, common use of an OP-Amp. The gain of this amplifier can be set to close to unity or greater than unity, but not unity or less than unity. Unlike the Inverting amplifier configuration this amplifier must accept the full voltage swing of the input signal, which can cause non-linear effects because of the moving of the input bias voltages and compressing of voltage headroom as the signal swings from one extreme to the other. Not all OP-Amps, however, are unity gain, or close to unity gain, stable. Check the OP-Amp spec sheet for more information. Audio Gadgets helps in design of this circuit by showing the effect of component changes or, in the case of specifying a desired gain, the component values needed.

Phase Splitter
The Phase Splitter OP-Amp configuration is useful for splitting the input signal into two out of phase signals. The balanced output is useful in high noise environments or in push-pull configurations. Two OP Amps are required and, presently, there are no common, off the shelf Phase Splitter IC's, which encompass this phase splitting function. The gain of this Phase Splitter amplifier can be set to close to unity or greater than unity, but not unity or less than unity. Audio Gadgets helps in design of this circuit by showing the effect of component changes or, in the case of specifying a desired gain, the component values needed.