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The Most Efficient Class of RF Power Amplifiers

When selecting an RF power amplifier, choosing one capable of delivering a high output power level is essential. We often specify this output level in several ways, including a saturated power level. This means the amplifier’s output level is constant when the input level increases. Efficiency is a measure of how well we convert energy to usable energy. A high-efficiency class means less heat, which is a bad by-product.

Class AB amplifier

The characteristics of the Class AB amplifier are similar to those of PNP-based amplifiers, with one key difference. Class ABs use a push-pull configuration to combine the positive and negative half-waves of an input signal. This configuration ensures that the amplifier does not exhibit crossover distortion during the amplification process.

Class AB amplifiers are also the most effective class of RF power amplifiers. However, this power amplifier design has many limitations. One of the most significant drawbacks is their high cost. These amplifiers are larger and more expensive than their Class A counterparts, making them a poor choice for radio equipment.

Another notable difference between Class AB amplifiers is their linearity. However, Class AB amplifiers have lower efficiency than Class A. This is because a Class AB amplifier’s output current is lower than the same amplifier’s output current in Class A. However, a Class AB amplifier can still achieve good linearity.

Class C power amplifiers

rf amplifiers

There are several different classes of RF power amplifiers. Class A, Class B, and Class C. These amplifiers have different operating modes. The first mode produces massive distortion. The second mode retains the lower DC component and increases the RF power to reach the highest efficiency. However, these amplifiers’ efficiency depends on ideal transistor characteristics; in reality, they do not have these characteristics.

Class A amplifiers consume more power and are, therefore, less efficient. A typical Class A amplifier is about 25-30% efficient but can be made more efficient with an inductively coupled configuration.

When you use a Class C amplifier to drive an RF power amplifier, you must ensure that the output is parallel to the RF power amplifier.

A parallel connection reduces the internal resistance of the RF power amplifier. However, it also doubles the plate current. The higher the plate current, the more power is developed.

Class G amplifier

Limiting the supply voltage across the output transistors dramatically enhances the efficiency of Class-G amplifiers. Because of the efficiency gain, Class-G amplifiers can operate from lower voltage supplies.

However, this means that they are more expensive. They can also produce higher output power but require more power.

The Class G amplifier is one of the most efficient RF power amplifiers. The boosting inverting power converter 32 supplies positive and negative voltages without a charge pump.

This avoids delays of positive and negative voltages. Furthermore, it can reduce the flywheel capacitance Cfly. The absence of a charge pump can reduce the cost and overall complexity of the Class G amplifier.

Class J amplifier

The Class J amplifier uses of Cout is not linear but nonlinear. This setup utilizes a capacitance tuned to a fundamental frequency at a low power level. We will also look at the time-domain voltage and current waveforms of Class J amplifiers.

A Class J amplifier is a high-efficiency RF power amplifier based on a bifurcated circuit. This means that the transistor conducts half the time while the other half is grounded.

Class S

Class A amplifiers use one switching transistor and have high gain and linearity. They also have a large conduction angle and very low signal distortion. However, the active element of a class A amplifier is prone to overheat, which can reduce its efficiency.

Class S+

A Class S+ amplifier is an excellent candidate to drive an RF power amplifier. This power amplifier can drive a switch-mode high-frequency amplifier. The frequency shift stage controls the carrier frequency of the output signal. Therefore, we can increase the Class S+ amplifier’s efficiency in higher frequency switching analog devices.

A Class A amplifier faces limitations from its high crossover distortion. This distortion results from the fact that two analog devices are involved in providing one-half of the sinusoidal wave. This means that the two halves combine and produce distortion when the two analog devices are inactive.

What is RF Power Amplifier Module?


An RF power amplifier module is an electronic component that produces a high-frequency signal. To produce this signal, it needs to be extremely compact. This compact design also helps to improve its life. A few features that you can look for in an RF power amplifier module are Compact design, High linearity, High gain, and High efficiency.


BC Systems Inc. has introduced a compact RF power amplifier module focusing on the modern GaN RF power transistor technology. It offers up to 20 W CW RF output power and operates in the frequency range of 25 to 1000 MHz. In addition, its small form factor and weight make it a perfect fit for small wireless applications.

Its performance is impressive, and its price aligns with its features. It has a high-quality build and can deliver up to 100 W RMS. It also has built-in blanking/enabling circuitry that helps conserve power and keep the amplifier cool.

RF power amplifier also helps to reduce noise, which is especially important for NMR reception. The Compact RF amplifiers come with a standard warranty.

High linearity

In modern communications systems, bandwidth is a limited commodity, and high spectral efficiency is essential for transferring huge amounts of data over finite channels. To achieve this goal, amplifier linearity is necessary for preserving the integrity of complex modulation formats. In addition, phase and amplitude control accuracy are necessary to maintain high data rates.

We can obtain High linearity of RF power amplifier modules without sacrificing efficiency. Different biasing schemes are employed to achieve this. For example, Class A operation is highly linear, while Class D is more power efficient. The difference between Class A and Class D operations depends on the type of input signal.

High gain output power

High-gain RF power amplifier modules can boost the power of a transmitter or receiver. They are generally housed in hermetically sealed modules and have a varying operating temperature of -55degC to +85degC. As a result, they are highly versatile and ideal for wideband amplification. In addition, they feature low noise and high RF gain.

The requirements for high-power amplifiers continue to rise across various industrial and military applications. Generally, mobile power amplifiers use gallium-arsenide-based transistors.

In the past, these devices could achieve Pouts up to 1W. However, new radio technologies such as 5G require high power levels for wide network coverage.

Wide dynamic range

A wide dynamic range is an essential parameter for RF power amplifiers. It refers to the power level range between a given input signal and a specified noise level. The dynamic range is often in decibels, a measure of the highest to the lowest level ratio. We measure it against a power level of one mW. Several parameters determine the highest level of the signal. The lower limit of the dynamic range is the 1-dB compression point, after which the system’s linearity becomes limited.

When an amplifier has a wide dynamic range, it can be helpful in many applications. For example, a transmitter may require a wide dynamic range, and an amplifier may be beneficial in boosting the power of a weak signal. Conversely, if an input signal has a low dynamic range, the resulting output signal must have a higher dynamic range.

How to Analyze Site Usage for RF Power Amplifiers

RF Power Amplifiers (RFPAs) increase the power of an RF input signal. They Analyze Site Usage by increasing the drain-to-source voltage and the associated current. This is known as the gain. The gain is the ratio of the signal at the output to the signal at the input.

The power efficiency of amplifiers depends on the amount of variation in the input signal. Modern digital modulation techniques typically produce signals with considerable variations in peak and average power. RF amplifiers will have a peak-to-average power ratio in the range of 10 to 30 decibels and enhance site navigation.

RF Power Amplifiers are a key component of 5G infrastructure, which is expected to be rolled out by telecom companies within the next half-decade. To meet this demand, semiconductor manufacturers are developing products that support the frequencies used by 5G networks. The market for RF Amplifiers will grow at a 17.1% CAGR over the next five years and enhance site navigation.

RF Power Amplifier design must maximize the amount of available input power. The input and output impedance specifications of RF amplifiers determine the amount of signal gain. RF Amplifiers are normally built with multiple stages, connected in a cascade or parallel configuration. The RF amplifier stages require a biasing network to provide bias voltages for each stage.


RF amplifiers are devices that transforms RF signals into electrical energy. Its output is proportional to the peak power of the signal. RF power amplifiers belong to different classes depending on the type of application. Each class has different functions and is used to achieve different design goals.

An RF amplifier has two main functions: amplifying input content and output. We usually express the output in power or voltage. The amplifier raises the input level to the desired level and outputs it outside. Its value reflects how well it does its job, and if it fails, it can lead to oscillation and damage to the outside world.