What is an Integrated Operational Amplifier?

Last Update Time: 2019-01-07 17:33:42

Operational Amplifier is a high-gain analog set consisting of multi-stage direct coupled amplification circuits into a circuit. The gain of the integrated operational amplifier is high ( up to 60 ~ 180dB ), the input resistance is large ( tens of thousands of ohms to one million ohms ), and the output resistance is small ( tens of ohms ), the common mode rejection ratio is high ( 60 ~ 170dB ), the offset and drift are small, and the output voltage is zero when the input voltage is zero, it is suitable for the input and output of positive and negative polarity signals.


In addition, the integrated operational amplifier has a +, -input and output terminals, and there is a power supply terminal, a common ground terminal, and some operational amplifiers and an external compensation circuit terminal, nulling end, phase compensation terminal and other additional terminals. The closed-loop amplification of an operational amplifier depends on the external feedback resistor, which is very convenient to use. The internal of the integrated operational amplifier is a direct coupling amplifier with a high voltage amplification factor, which is mainly composed of input, middle and output parts. The input part is a differential amplification circuit, which has the same phase and the opposite phase; the voltage variation of the former is the same as that of the output voltage, and the latter is the opposite. The middle part provides high voltage amplification, and the output part is amplified to connect the load.


The main parameters

Characterizing the performance of the integrated operational amplifier are very large, and the common ones are as follows :

 ( 1 ) Open loop differential mode voltage amplification is called open-loop gain , said the operational amplifier itself, the amplification capacity, generally 50,000 to 200,000 times.


( 2 ) The input offset voltage indicates that the output voltage deviates from a predetermined value at static time, generally 2 to 10 mV.


( 3 ) The unit gain bandwidth represents the frequency of differential mode voltage amplification down to 1, generally around 1 MHz. The unity gain bandwidth is equal to the gain bandwidth product. The gain bandwidth product is the product of the amplification and the bandwidth of an operational amplifier. The gain bandwidth product is a fixed value for each op amp, the higher the gain, the narrower the bandwidth, the lower the gain, the wider the bandwidth.


( 4 ) the conversion rate represents the adaptability of the operational amplifier to the mutated signal. Generally around 0.5V / s.


( 5 ) Output voltage and current denote the output capability of the operational amplifier. The peak to peak of the output voltage is 1 ~ 3V lower than that of the supply voltage, and the short circuit current is about 25 mA.


( 6 ) Static power consumption represents the power consumption of an operational amplifier without signal. When the supply voltage is 15V, the static power consumption of bipolar transistor is 50 to 100 mW, and the field-effect transistor type is 1 mW.


( 7 ) Common mode rejection ratio ( CMRR ) denotes the ratio of amplifier to differential mode signal amplification and common-mode signal amplification. Generally 70 ~ 90dB.


This article is from Allicdata Electronics.