In addition, to prevent low-frequency oscillation or high-frequency oscillation caused by the internal resistance of the power supply, an electrolytic capacitor (10mF) and a high-frequency filter capacitor (0.01 mF ~ 0.1mF) should be connected.
To make the amplifier work stably, a certain frequency compensation network must be added to eliminate the self oscillation. Under the condition of deep negative feedback, it is easy to cause self-excited oscillation. The operational amplifier is a high-amplitude multi-stage amplifier. For integrated op amps without internal zeroing terminals, external zeroing methods should be used. Commonly used zeroing methods include internal zeroing and external zeroing. This is the zero setting of the operational amplifier. In order to improve the operation accuracy of the circuit, it is required to compensate the error caused by the offset voltage and the offset current. At this time, in order to ensure that the internal unit circuit of the operational amplifier has a suitable static operating point, a DC potential must be added to the input end of the op amp.ĭue to the influence of the input offset voltage and input offset current of the integrated op amp, when the input signal is zero, the output is often not equal to zero.
Single-supply operation connects the -V EE pin of the op amp to ground. In this way, the signal source can be directly connected to the input pin of the op amp, and the amplitude of the output voltage can make the positive and the negative symmetrical. The positive power (+ E) and negative power (-E) relative to the common terminal (ground) are connected to the + V CC and -V EE pins of the op amp, respectively. For different power supply modes, the requirements for input signals are different. The integrated op amp has two power terminals + V CC and -V EE, with different power supply methods. Using Operational Amplifier as a Comparator For example, the signal source is a voltage source or a current source the nature of the load, and whether the output voltage and current of the integrated op amp meet the requirements operating voltage range, power consumption, and volume of the integrated op amp.įigure 1. When selecting an integrated op amp, some factors should be considered in addition to the figure of merit coefficient K. Therefore, for circuits that amplify AC signals such as audio and video, op amps with large SR are better for circuits that handle weak DC signals, op amps with high accuracy are more suitable (both offset current, offset voltage and temperature drift are relatively small). The smaller the Iib and VOS values, the better the DC characteristics of the op amp. The larger the value, the better the AC characteristics of the operational amplifier The input bias current of the amplifier is lib, the unit is nA VOS is the input offset voltage in mV. Generally, the merit coefficient K is used to measure the excellent degree of integrated operational amplifiers, which is defined as: where SR is the slew rate and the unit is V / ms. The evaluation of integrated op amps depends on their overall performance. For example, LM324 and LF347 always integrate four op amps together in a circuit. When using multiple op amps in a system, use as many op amp integrated circuits as possible. Where there are no special requirements, try to use a universal integrated operational amplifier as much as possible, which can reduce costs and easily replace. In various systems, because of different application requirements, the performance requirements of operational amplifiers are also different. Integrated operational amplifiers are one of the most widely used devices in analog integrated circuits. Ⅴ One Question Related Op Amp and Going Further
This Video is Introducing Operational Amplifier Applications in the Circuit Catalog
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