The detailed and specific performance characteristics of a particular operational amplifier can be found on the appropriate data sheet. An operational amplifier data sheet will normally provide many nongeneric electrical characteristics. The electrical characteristics provided are for a specified supply voltage and ambient temperature and usually will have minimum, typical, and maximum values.
Major operational amplifier characteristics and their meaning are as follows:
- Input offset current (110) – the difference between the two input bias currents when the output voltage is zero.
- Common-mode input voltage range (VICR) the range of the common-mode input voltage (i.e., the voltage common to both inputs).
- Output short-circuit current (lOS) – the maximum output current that the operational amplifier can deliver into a short circuit.
- Output voltage swing (VOpp) – the maximum peak-to-peak output voltage that the operational amplifier can produce without saturation or clipping occurring. This characteristic is dependent upon output load resistance.
- Large-signal differential voltage gain (AVD) the ratio of the ouput voltage swing to the input voltage swing when the output is driven to a specified large-signal voltage (typically ± to V).
- Slew rate (SR) – the time rate of change of the closed-loop output voltage with the operational amplifier circuit having a voltage gain of unity (I).
- Supply current (ICC> – The total current that the operational amplifier will draw from both power supplies when unloaded (per amplifier for multiunit packages).
- Common-mode rejection ratio (CMRR) – a measure of the ability of an operational amplifier to reject signals that are present at both inputs simultaneously. The ratio of the common-mode input voltage to the generated output voltage and is usually expressed in decibels (dB).
The preceding paragraphs have discussed basic operational amplifier characteristics. The following paragraphs will provide more detailed information. The specific characteristics that will be discussed are as follows:
- Gain and frequency response
- Difference of input resistance
- Influence of input offset voltage
- Input offset compensation
- Input offset voltage temperature coefficient
- Influence of input bias current
- Influence of output resistance
- Input common-mode range
- Common-mode rejection ratio (CMRR)
- Slew rate
- Phase margin
- Output voltage swing
- Feed-forward compensation