Part I - Background, Characteristics and Fundamental Operations

Key Concepts

• The operational amplifier, often referred to as an op-amp, is a very high gain, directly coupled voltage amplifier with two inputs(V_IN+, V_IN-) and a single output(V_OUT).
• Widely used in electronic applications such as audio, medical devices, and automotive applications.
• Directly Coupled (DC) voltage amplifier maintains its gain at low frequencies down to dc.
• Ability to recognize the proper pin orientation of an integrated circuit
• The differential amplifier as the first stage of an op-amp
• The differential input mode of operation
• The common-mode input of operation
• The differential voltage gain (Av(d))
• The common-mode gain (Acm)
• Op-amps amplify any signal that is applied to the inputs.
• Electrical noise can have a major impact on op-amp operation.
• The ability of an op-amp to reject common-mode noise signals (CMRR)
• The rate at which the output of an op-amp can change in response to a change at the input (slew rate)

Op-amps can be configured as amplifiers, comparators, integrators, differentiators, filters, oscillators, and special-purpose amplifiers. If configured as an amplifier, an op-amp can be connected in closed-loop and open-loop configurations using the concepts of both negative and positive feedback.

• Microchip offers a wide selection of op-amps.

MCP661 60 MHz, 32 V/μs Rail-to-Rail Output (RRO) Op-Amp in SOIC-8