Power amplifier printed circuit board and prototype debug
| Power amplifier, referred to as "power amplifier", in the conditions of a given distortion rate, which can produce maximum power output to drive a load (eg, speaker) amplifier. Copy for the power amplifier PCB board, copy board and the power amplifier model of the power amplifier circuit board production, China Lan technology to the professional PCB copy board team combines precision PCB copy board software successfully completed the PCB copy board a series of work. (Including the production of PCB drawing files, and documentation of schematics, BOM BOM production, on-board chip decryption PCB proofing system board, supporting the procurement of IC components, PCBA assembly and welding and model debugging and other services.)
Power Amplifier Description:
Current control action of the transistor or FET voltage control of power-converter in accordance with the current of the input signal changes. Because the sound waves of different amplitude and different frequencies, the AC signal current, the transistor's collector current is β times the base current is always beta transistor exchanges magnification, the application of this point, if small signals injected into the base. current collector flow over equal to β times the base current, then the signal blocking capacitor to isolate, you get the current (or voltage) is the beta times the signal, this phenomenon transistor enlarge role. After a constant current and voltage amplification, the power amplifier.
1, Class A amplifiers
The main features of the class A amplifier: The amplifier's operating point Q is set near the midpoint of the load line, the transistor conduction in the entire period of the input signal. The amplifier can be a single tube, you can also push-pull work. The amplifier operates in the linear range of the characteristic curve, transient distortion and alternating less distortion. The circuit is simple and convenient debugging. But the efficiency is low, the transistor power consumption, only 25% of the theoretical maximum value of the power, and large nonlinear distortion. The design is basically due to relatively low efficiency is not re-use.
2, B amplifier
Class B amplifier is characterized by: a static point of the amplifier (VCC) of, when there is no signal input, output almost no power consumption. Vi positive half cycle, Q1 turns on Q2 is off, the output is correct half cycle sine wave; Similarly, when Vi is the negative half-wave sine wave (as shown in dotted lines), it is necessary to use two push-pull work. Which is characterized by high efficiency (78%), but because of the amplifier there is a nonlinear region, so the disadvantage is that the "crossover distortion". When the signal is between-0.6V ~ 0.6V, Q1 Q2, are unable to conduction. These amplifiers also gradually be abandoned by the designer.
3, Class AB amplifiers
The main features of the class AB amplifier is: transistor turn-on time slightly larger than the half-cycle, with two push-pull. Avoided to pay more distortion. Alternating distortion can be offset by the even harmonic distortion. Efficient, smaller transistor power characteristics.
4, D-class amplifier
Class D (digital audio power) amplifier is a pulse signal, an input analog audio signal or PCM digital information converted into a PWM (Pulse Width Modulation) or PDM (pulse density modulation) PWM or PDM pulse signal to control power switching device on / off audio power amplifier, also known as switching amplifiers.
5, T-class amplifier
The same class T power amplifier output circuit and PWM Class D power amplifiers, power transistors work in switching state, the efficiency of Class D power amplifier quite.
The power amplifier consists of:
The RF power amplifier (RF PA) is an important part of the various wireless transmitters. Transmitter front-end circuit, the power of the RF signal generated by the modulated oscillator circuit is very small, need to go through a series of amplification buffer stage, the intermediate amplifier stage, the final stage power amplifier stage, to obtain sufficient RF power in order to feed out to the antenna radiation. In order to obtain a large enough RF output power, RF power amplifier.