Electrotechnics self study notes 1.21

Non exam preparation materials
1.21

Chapter 15 Basic amplifier circuit

The last stage or the last preceding stage of multistage amplification circuit is generally the power amplification stage , It is used to power amplify the low-frequency signal sent by the pre voltage amplification stage , To drive the load . requirement ：1. It can output as much power as possible without distortion .2. Due to high power , We need to improve efficiency （ The ratio of the AC signal power obtained by the load to the DC power supplied by the power supply ）
Complementary symmetrical amplification circuit ：OTL、OCL.

Chapter 16 Integrated operational amplifier

The integrated circuit （ see 1.18 Expand knowledge ） The components of the whole circuit and the connections between them are manufactured on a semiconductor chip at the same time , Form a whole . Small volume , Light weight , Low power consumption , Stable work .
Digital integrated circuits and analog integrated circuits （ Integrated operational amplifier 、 Integrated power amplifier 、 Integrated regulated power supply 、 A / D converter ）
The circuits of integrated operational amplifiers can often be divided into input stages （ Differential amplification ）、 Intermediate stage （ Common emitter ）、 Output stage （ Emitter output ） And bias circuit （ Provide stable and appropriate bias current ）.

Expand knowledge

1. Self excited oscillation ： It refers to the steady and continuous oscillation generated by itself without additional excitation signal . If no input signal is added to the input end of the amplifier , The output end still has a certain amplitude and frequency output signal , Not conducive to amplification circuit , It will make the amplification circuit unstable , Or burn out .
2. Invariance principle is a theory in automatic control theory that studies the influence of restraining and eliminating disturbance on control system . The actual control system will be affected by external disturbances . If this disturbance can be measured , It is possible to use it to produce a controlling effect , To eliminate its impact on output . Phase compensation control refers to the automatic control of DC output voltage by controlling the phase of trigger pulse based on the invariance principle .
3. Analog to digital converter, i.e A/D converter , Or abbreviation ADC, It usually refers to an electronic component that converts an analog signal into a digital signal . The usual analog-to-digital converter converts an input voltage signal into an output digital signal . Because the digital signal only represents a relative size . Therefore, any analog-to-digital converter needs a reference analog quantity as the conversion standard , The most common reference standard is the maximum convertible signal size . The digital output represents the size of the input signal relative to the reference signal .
4. Constant current source ： When the transistor works in the amplification region IB Fixed time , Its IC Hardly follow UCE And change , It shows constant current characteristic , The dynamic resistance of constant current components is very high , But the DC voltage drop at both ends of it is not big .