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
• Pin orientation of a packaged op amp
• 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