PA90

Linear - Amplifiers - Instrumentation, OP Amps, Buffer Amps

PA90 is a type of amplifier that belongs in the category of instrumentation, OP Amps, and buffer amps, linear amplifiers. A linear amplifier is based on a linear design, as opposed to a switching amplifier which employs pulses to boost and control the signal. Linear amplifiers are popularly employed in many devices, from home receivers to medical equipment, scientific research and military applications. They offer both a high power gain and low noise output, allowing for a greater amount of dynamic range and detail in the signal amplification.

Unlike switching or class-D amplifiers, the PA90 does not employ any switching elements and instead works using a traditional fully-differential configuration. This approach means that the amplifier can achieve better linearity with less distortion, providing a better overall sound reproduction and allowing for a much higher power. The PA90 also uses an encapsulated output stage, which reduces the risk of potential noise due to grounding issues.

Working Principle

The PA90 uses the following working principle: all input signals are given to the operational amplifier, then amplified and sent directly to the output stage. The operational amplifier has two stages: a voltage series stage and a voltage shunt stage. The voltage series stage amplifies the input while the voltage shunt stage monitors and keeps the signal within the required Vcc (Voltage Controlled Connector).

At the output stage, an inverting driver is used to handle the output signal. It is composed of three transistors for greater current capacity and better linearity. These transistors switch the output signal to the required voltage. The output stage is then fed to the last stage: the power output stage, which is created by classical Class A amplifying transistors. These are designed to provide a clean and powerful output signal, as required by the application.

The PA90 has several power supply rails, which are used to control the voltage levels for both the first and last stages of amplification. The first stage is powered by the VOC rail, which helps to control the voltage via a low level of impedance. The second stage is powered by the VCC rail, which is the main supply voltage to the amplifier. Finally, the last stage is powered by the VFD rail, which is used to control the voltage of the gate transistor.

Application Fields

The PA90 is a versatile amplifier that can be used in a wide range of applications, such as home receivers and portable audio players. It is also commonly used in medical equipment such as ultrasound machines and defibrillators, as well as scientific research, military applications and communication systems.

The PA90 is an excellent choice for sound and audio system applications due to its low noise and high power gain. In addition, its encapsulated output stage increases the longevity of the amplifier and reduces noise due to the reduced risk of ground issues.

Conclusion

The PA90 is a versatile amplifier that can be used for a wide range of applications, thanks to its low noise output and high power gain. The amplifier also offers an encapsulated output stage, which reduces the risk of noise due to ground issues. In addition, its dual stage design, with a voltage series and a voltage shunt stage, helps to ensure better linearity and reduced distortion, making it an ideal choice for applications such as home receivers, medical equipment, scientific research, military applications and communication systems.