It is divided into three working states: A, B and C. The current flow angle of Class A amplifier is 360 degrees, which is suitable for small signal and low power amplification. The circulating angle of class B amplifier current is about equal to 180 degrees; The current flow angle of Class C amplifier is less than 180 degrees. Both Class B and Class C are suitable for high-power operation. Among the three working conditions, the output power and efficiency of Class C are the highest. Most high-frequency power amplifiers work in Class C, but the current waveform of Class C power amplifier is too distorted to be used in low-frequency power amplifier, and can only be used in resonant power amplifier with tuning ring as load. Because the tuning loop has filtering ability, the loop current and voltage are still very close to sine wave, and the distortion is very small.
2. When drawing, enlarge or reduce the application of graphics. Also known as magnifying ruler.
Classification introduction of integrated operational amplifier
Main categories of integrated operational amplifiers
The following describes integrated operational amplifiers with different characteristics.
1. General integrated operational amplifier
General integrated operational amplifier means that its technical parameters are moderate and can meet the requirements of most cases. General-purpose integrated operational amplifiers are divided into type I, type II and type III, in which type I is a low gain operational amplifier, type II is a medium gain operational amplifier and type III is a high gain operational amplifier. Type I and Type II are basically early products. Their input offset voltage is about 2mV, and the open-loop gain is generally greater than 80dB.
2. High-precision integrated operational amplifier
High-precision integrated operational amplifiers refer to those with small offset voltage, very small temperature drift and very high gain and * * * mode rejection ratio. The noise of this operational amplifier is also relatively small. Among them, the offset voltage of single-chip high-precision integrated operational amplifier can be as small as a few microvolts, and the temperature drift is as small as tens of microvolts per degree Celsius.
3. High-speed integrated operational amplifier The output voltage conversion rate of high-speed integrated operational amplifier is very high, and some of them can reach 2 ~ 3 kV/μ s. ..
4. High input impedance integrated operational amplifier
High input impedance integrated operational amplifier has large input impedance and small input current. The input stage of this kind of operational amplifier often adopts MOS tube.
5. Low power integrated operational amplifier
Low-power integrated operational amplifier has low current and low power supply voltage. The power consumption of the whole operational amplifier is only a few tens of microwatts. This kind of integrated operational amplifier is mostly used in portable electronic products.
6. Broadband integrated operational amplifier
Broadband integrated operational amplifier has a wide frequency band, and the unit gain bandwidth can reach more than gigahertz, which is often used in broadband amplification circuits.
7. High voltage integrated operational amplifier
Generally, the power supply voltage of integrated operational amplifier is below 15V, while the power supply voltage of high-voltage integrated operational amplifier can reach tens of volts.
8. Power integrated operational amplifier
The output stage of the power integrated operational amplifier can provide a large power output for the load.
Brief introduction of optical fiber amplifier
Optical fiber amplifier can not only amplify optical signals directly, but also has all-optical amplification function of real-time, high gain, broadband, online, low noise and low loss, and is an essential key device in the new generation of optical fiber communication system. Because this technology not only solves the limitation of attenuation on the transmission speed and distance of optical network, but also creates wavelength division multiplexing in 1550nm band, it will make ultra-high speed, ultra-large capacity and ultra-long distance wavelength division multiplexing (WDM), dense wavelength division multiplexing (DWDM), all-optical transmission and optical soliton transmission become reality, which is an epoch-making milestone in the development history of optical fiber communication. At present, there are mainly erbium-doped fiber amplifier (EDFA), semiconductor optical amplifier (SOA) and fiber Raman amplifier (FRA), among which erbium-doped fiber amplifier has been widely used in long-distance, large-capacity and high-speed optical fiber communication systems, access networks, optical fiber CATV networks, military systems (radar data multiplexing, data transmission, guidance, etc. ) and other fields as power amplifiers.
Fiber amplifier is generally composed of gain medium, pump light and input-output coupling structure. At present, there are three kinds of fiber amplifiers: erbium-doped fiber amplifier, semiconductor optical amplifier and fiber Raman amplifier. According to its application in optical fiber network, optical fiber amplifier has three different uses: it is used as a power amplifier at the transmitter to improve the power of the transmitter; The optical preamplifier is made in front of the receiver to greatly improve the sensitivity of the optical receiver; Relay amplifier is used in optical fiber transmission line to compensate optical fiber transmission loss and extend transmission distance.