Non-exam preparation materials
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Chapter 16 Integrated Operational Amplifier
The application of operational amplifier in signal operation:
1. Proportional operation: inverting input: inverting proportional amplifier; non-inverting input: voltage follower (following performance is better than emitter output)
2. Addition operation: control the difference of a variety of music Volume size
3. Subtraction operation: making accompaniment bands
. The application of operational amplifiers in signal processing:
1. Active filter: frequency selection circuit, select useful signals and suppress useless signals. Divided into low pass, high pass, band pass and band stop.
2. Sample and hold circuit
3. Voltage comparator: data monitoring, automatic control
of zero-crossing comparator, hysteresis comparator, hysteresis comparator has two advantages over zero-crossing comparator: 1. It can accelerate the transition process of output voltage, 2. The hysteresis improves the anti-interference ability of the circuit.
Expand knowledge
1. Passive filter, also known as LC filter, is a filter circuit that uses a combination of inductance, capacitance and resistance to filter out certain one or more harmonics. The most common and easy-to-use passive filter structure is Connect the inductor and capacitor in series.
2. Active filter: Because the operational amplifier is an active device, it is called an active filter. Its application can overcome the shortcomings of traditional harmonic suppression and reactive power compensation methods such as LC filters (traditional only fixed compensation) , Realize dynamic tracking compensation, and can compensate both harmonics and reactive power.
3. Sample and hold circuit (sample/hold) is also called sample and hold amplifier. When performing A/D conversion on an analog signal, a certain conversion time is required. During this conversion time, the analog signal must remain basically unchanged, so as to ensure the conversion accuracy. The sample and hold circuit is the circuit that realizes this function.
4. The zero-crossing comparator is used to detect whether an input value is zero. The principle is to use a comparator to compare two input voltages. One of the two input voltages is the reference voltage Vr, and the other is the voltage to be measured Vu. Generally, Vr is connected from the non-inverting input terminal, and Vu is connected from the inverting input terminal. According to the result of comparing the input voltage, the forward or reverse saturation voltage is output. When the reference voltage is known, the measurement result of the voltage to be measured can be obtained. When the reference voltage is zero, it is a zero-crossing comparator.
5. Hysteresis comparator (hysteresis comparator) is a comparator with hysteresis loop transmission characteristics. It can also be understood as a single-limit comparator with positive feedback. On the basis of the inverting input single threshold voltage comparator, a positive feedback network is introduced to form an inverting input hysteresis comparator with double thresholds.