The main technical performance indicators of the amplifier are amplification factor, amplitude-frequency characteristic, noise figure and matching impedance.
1. Voltage amplification factor (gain). An amplifier is a module used to increase a weak signal (voltage, current, or power) to a desired value. Therefore, indicators describing the amplification capability of an amplifier include a voltage amplification factor, a current amplification factor, and a power amplification factor. The most common one is voltage amplification. coefficient.
2. Amplitude-frequency characteristics (working bandwidth). Since the impedance and characteristics of various components in the amplifier are frequency dependent, the amplifier has different amplification capabilities for signals of different frequencies. Therefore, the amplifier can maintain the amplitude-frequency characteristic relatively flat over a certain signal frequency range, and the phase shift is 180°; and the signal gain lower or higher than this frequency band is significantly reduced, and the additional phase shift is increased. The frequency range in which the gain is typically reduced by no more than 3 dB is referred to as the operating bandwidth of the amplifier. There are also more stringent requirements, namely 1dB or 0.5dB bandwidth, that is, the gain fluctuations in this frequency range are not more than 1dB or 0.5dB respectively.
3. Noise figure. An important indicator of an amplifier is its own signal-to-noise ratio, which directly affects the sensitivity of the amplifier. Once the input signal is flooded by noise in the amplifier, a useful signal cannot be obtained. In order to better measure the sensitivity of the amplifier, it is generally characterized by a noise figure.
4. The matching impedance of the amplifier. When the load resistance is equal to the internal resistance of the signal source, it is called impedance matching, and the load can get the maximum power from the signal source. For the amplifier, the input impedance of the amplifier is also required to be equal to the characteristic impedance of the input interface. The output impedance is equal to the load impedance of the output interface, and the impedance of the amplifier is completely matched. The input impedance of the amplifier is the load impedance of the amplifier street, and the standard signal source on the street of the input of the amplifier, then the ratio of the input voltage to the input current is the input impedance. The output impedance is the characteristic impedance specified on the input end of the amplifier (the high-frequency circuit is 50Ω or 75Ω). When the output terminal is connected to the standard signal source, the ratio of the output voltage of the standard signal source to the output current is the output impedance. The output impedance of a standard source is the impedance required for the amplifier design. Generally, the input impedance and output impedance of a high frequency amplifier or a microwave amplifier are 50 Ω, and the input impedance and output impedance of an image transmission system are 75 Ω. The input impedance of the low frequency amplifier or DC amplifier is 600Ω, and the output impedance is determined as needed.
The amplifier circuit is a key module in the signal transmission process. The telemetry and remote control systems used in various devices such as radar, communication, navigation, missile, rocket satellite, etc., all capture weak signals from atmospheric targets. These weak signals cannot be directly connected to the control or display portion of the system, and the captured weak target signals must be amplified to the required magnitude to operate in the system. Therefore, its application range covers almost all automatic control systems and measurement systems. In short, with the miniaturization and modularization of various electronic control systems, the application range of hybrid integrated amplifiers will become more and more extensive.
Technology development trend
The overall development trend of hybrid integrated amplifiers is toward miniaturization, low noise, and high gain. However, since the amplifier circuits are often different in their use, their circuit topology and performance specifications are completely different, so there are quite a few types of amplifiers. The development trend of amplifiers for different purposes is also different. With the continuous development of science and technology, the distance between various weapons and equipment, telemetry and remote control systems is getting farther and farther. Therefore, the receiver preamplifier should have a higher signal-to-noise ratio, greater gain, and higher resolution, thereby greatly increasing the range of the communication system.
The trend in log amps is toward larger input dynamic range, higher amplification gain, and better output linearity. The larger the dynamic range of the input, the greater the gain, which makes the signal acquisition more powerful. At the same time, the better the output linearity, the higher the accuracy of the signal obtained. For example, in the use of radar, the accuracy and range of the radar are greatly improved.
The pulse width modulation amplifier is the execution component of the DC servo system - the motor motor drive circuit, which is uesd to receive the DC error signal fed back from the system and convert it into a widened square wave signal. That can make DC motor work in order to control closed loop of system speed and position.
The advantages of high-power pulse width modulation amplifier are large output current (30A), high output voltage (500V), large output power, small size, light weight, high efficiency (97%), high reliability, convenient control (temperature control, current control),etc; With H-grade quality, the product can be widely used in aerospace, aviation, weapons, ships, electronics and so on.