Operational Amplifiers Information
Operational amplifiers (op amps, op-amps) are general-purpose, closed-loop devices that are used to implement linear functions. They compare two incoming signals and release a third signal that is an amplified measure of the difference between the two. Operational amplifiers are used in signal processing circuits, control circuits, and instrumentation for automotive, commercial, industrial, medical and military applications. Input impedance and output impedance vary by op-amp application. For example, in audio applications, the input impedance is usually several times higher than the output impedance. In video and high frequency systems, the impedance of inputs, transmission lines, and outputs are designed to be the same.
Performance Specifications and Features
Operational amplifiers (op amps, op-amps) differ in terms of performance specifications and features. Examples include minimum closed-loop gain (AVCL), supply voltage (VS), source current (IS), input offset voltage (VOS), input bias current (IBIAS), and quiescent current (IQ). When selecting operational amplifiers, designers should also consider common mode rejection ratio (CMRR), power supply rejection ratio (PSRR), gain-bandwidth product (GBW), slew rate (SR), input voltage noise (Vn), input current noise (In), and output voltage swing (VOM). Bandwidth and operating temperature are also important considerations. Features for operational amplifiers include rail-to-rail input, rail-to-rail output, single supply, thermal shutdown protection, and on-chip electrostatic discharge (ESD) protection.
Variations
Operational amplifier chips (op amp chips, op-amp chips) vary by integrated circuit (IC) package type, life cycle stage, pin count, and number of devices. Some op-amp chips are available in dual in-line package (DIP), ceramic dual in-line package (CDIP), or plastic dual in-line package (PDIP) designs. Other op amp chips use single in-line package (SIP) chip scale package (CSP), or small outline IC (SOIC). Operational amplifiers with transistor outline (TO), small outline transistor (SOT), and plastic leaded carrier (PLCC) IC packaging are also available. Like other ICs, op amp chips follow the product lifecycle stage as defined by EIA-724. The stages in the model are defined as introduction, new product, rapid growth, maturity, declining, saturation, phase-out, and removed.
Standards
There are two major standards for operational amplifiers: RoHS and ELV. Restriction of Hazardous Substances (RoHS) is a European Union (EU) directive that requires all manufacturers of electronic and electrical equipment sold in Europe to demonstrate that their products contain only minimal levels of the following hazardous substances: lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyl, and polybrominated diphenyl ether. The EU’s End of Life Vehicles (ELV) directive requires that certain automotive products be free (except for trace impurities) of mercury, cadmium and lead. Operational amplifiers that meet other national or international standards are also available.
