Battery charge and discharge testerHigh voltage generator circuit diagram10kv reclosingPower amplifier, referred to as power amp, generally refers to a most basic equipment in audio systems, commonly known as "amplifier". Its task is to amplify the weak electrical signals from the signal source (in professional audio systems, from the mixer) to drive the speakers to produce sound. It can also refer to other devices that perform power amplification.
The function of the power amplifier is to amplify the weak signals from the audio source or preamplifier, and drive the speakers to produce sound. In a good audio system, the role of the power amplifier is indispensable.
Power amplifiers are the largest family among various audio equipment. Their main function is to amplify the relatively weak signals input from the audio source equipment, generating sufficient current to drive the speakers for sound reproduction. Due to considerations of power, impedance, distortion, dynamics, and different usage ranges and control adjustment functions, different power amplifiers also differ in internal signal processing, circuit design, and production processes.
①MOS tube power amplifiers have the advantages of low driving power, high output power, negative temperature coefficient of output drain current, qualifications and honors, as well as high operating frequency and simple biasing. Using the output of an operational amplifier as the input of OCL achieves the effect of suppressing zero drift.
The current push stage usually consists of one to two stages. To reduce output impedance and increase damping factor, a two-stage current push is often used. To prevent switching distortion in the current push stage, a better approach is to use MOS tubes and increase the quiescent current of this stage, so that this stage does not produce switching distortion. Since the current push stage is always in the amplification region under any circumstances, the current output stage is also always in the amplification region, so the output stage also does not produce switching distortion or crossover distortion.
①The low-frequency warmth is worse than that of transistor power amplifiers. MOSFET switching field-effect transistors are easily damaged by output and input overload. MOSFET field-effect transistors have the fundamental advantages of transistors. However, shortly after use, it was found that the reliability of this power amplifier was not high (unable to be protected by external circuits), the switching speed did not improve much, and the maximum output power was only 150W/8Ω. In the early 1990s, MOSFET manufacturing technology made significant breakthroughs, and a high-speed MOSFET high-power switching field-effect transistor emerged.
After years of research, the Spanish company ECLER overcame the non-destructive protection system with its patented SPM technology, and launched the third-generation power amplifier product that combines the advantages of both tube amplifiers and transistor amplifiers, gradually gaining application worldwide. The mid-frequency and high-frequency sound quality of the third-generation MOSFET power amplifier is close to that of tube amplifiers, but the low-frequency warmth is somewhat inferior to transistor amplifiers, three-phase capacitance and inductance tester parameters. In addition, MOSFET switching field-effect transistors are easily damaged by output and input overload.
⑤The low frequency of MOS tubes is too hard. There is a simple way to hear the so-called tube sound with a MOS power amplifier: replace the voltage push transistor in an ordinary transistor power amplifier with a JFET. JFET truly has the tube sound.
Power amplifier circuits often require strong ability to drive loads. From the perspective of energy control and conversion, power amplifier circuits are not fundamentally different from other amplifier circuits in nature. The power amplifier neither simply pursues high output voltage nor simply pursues large output current, but rather pursues outputting as much power as possible under a given power supply voltage.
This circuit uses an N-channel and a P-channel field-effect transistor in a push-pull configuration, where RP2 and RP3 are bias resistors used to adjust the quiescent operating point of the circuit. The relationship between the characteristic frequency fT and the upper cutoff frequency fH of the amplifier circuit is: fT≈fhβh, and the relationship between the rise time tr of the system step response and the upper cutoff frequency of the amplifier circuit is: trfh=0.35.
