Operational Amplifier Circuits
Operational amplifiers are extremely high gain amplifiers with extremely high gain and flat frequency response from DC to well above 1,000,000 Hz. The Band pass of one of least expensive and oldest op amps, the u741, is 1Mhz. They have a differential amplifier input stage which gives them excellent DC and low frequency response. This makes them well suited for processing transducer outputs, and amplifying non-sinusoidal waveforms such as the ramp voltages used for for CRT deflection.
Above: Inverting Amplifier
Above: Non-Inverting Amplifier
Click to see OP AMP used in a DAC.