Although the Doherty power amplifier is more efficient, its linearity is usually poor, and it needs to be linearized by digital predistortion technology. In order to meet higher and higher communication speeds, the working bandwidth of Doherty amplifiers is also wider and wider. Therefore, in order to evaluate the linearization performance of Doherty amplifiers, it is necessary to build a broadband digital predistortion platform. In this paper, a linear pre-distortion platform based on R&S signal and spectrum analyzer (FSW26) is used to linearize the laboratory's broadband Doherty power amplifier. Experiments show that whether it is single frequency, concurrent dual frequency, or concurrent multi-frequency operation mode, broadband Doherty power amplifier with digital pre-distortion technology can obtain better linearity.
1 IntroductionAs the communication rate becomes higher and higher, the signal bandwidth becomes wider and wider, especially the adoption of carrier aggregation technology, so that the bandwidth required for the transmitter is also significantly increased. Faced with the challenge of carrier aggregation technology, a more economical transmitter solution is a concurrent multi-frequency transmitter. In this scenario, a transmission channel must support the traditional single-carrier communication signal, and also needs to support the multi-frequency carrier aggregation signal. Therefore, the bandwidth of the transmission channel is also significantly increased. The bandwidth of the power amplifier on the transmit channel is the main bottleneck of the transmit channel bandwidth. Especially the Doherty power amplifier, although its efficiency is significantly better than the traditional class AB power amplifier, the typical Doherty power amplifier has a relative bandwidth of only about 10%. In order to face the challenges of concurrent multi-frequency transmitters, the design of broadband Doherty amplifiers has become the focus of power amplifier research in recent years.
Doherty power amplifiers have poor linearity and usually require digital predistortion (DPD) to be used in the base station. Therefore, in addition to the efficiency and bandwidth indicators of broadband Doherty power amplifiers, whether linearization is a topic of concern in the industry. After the Doherty amplifier design is completed, the linearity performance of the DPD needs to be tested to complete the overall performance evaluation of the designed amplifier.
2. Principle of digital predistortionUnder normal circumstances, the power amplifier is more efficient under saturated operation. Take the Doherty power amplifier as an example. At the power point of retreat, the main power amplifier works in saturation state. At the peak power point, the main power amplifier and the auxiliary power amplifier are at Saturated state, therefore, Doherty power can achieve higher efficiency at both peak and retreat points. However, a power amplifier in a saturated state exhibits nonlinear distortion due to gain compression, that is, the bandwidth of the output signal is wider than the original input signal.
Figure 1, the number indicates the true principle diagram
In order to eliminate this distortion of the power amplifier, the idea of ​​the digital pre-distortion technique is to pre-process the input signal in the digital domain, which is equivalent to superimposing the components of the same size and opposite phase on the baseband signal, and finally superimposing the components. The distortion component generated by the power amplifier itself cancels out and achieves the purpose of linearization. Figure 1 illustrates the principle of digital predistortion from the perspective of gain. It can be seen that the gain of the amplifier (the slope of the curve) is reduced when the input signal is large, and the gain of the predistortion module (the slope of the curve). Then, when the input signal is large, the gain is increased, and finally the two are cascaded, so that the input and output curves are a straight line (gain is flat).
About this project
ADVANCED SAFE CHARGING: The USB-C MacBook Pro Charger Power Adapter combines advanced safety features and premium fire-resistant materials with built-in protection against overheating, overcharging, overcurrent, and overvoltage.Fast Charge with PD 3.0: The USB C charger features a Thunderbolt 3 USB C port for full-speed charging, charging a 16-inch MacBook Pro in just 1 hour and 30 minutes. (Note input: AC 100-240V-1.5A(1.5A), 50-60Hz, output: 20.5V=4.7A, 15V=3A, 9V=3A or 5.2V=2.4A.
Wide Compatibility: Macbook Charger is compatible with Mac Pro 16 15 14 13", Mac Air 13", i-Pad Pro 11"/12.9", and also compatible with other USB-C enabled devices. Such as laptops, cameras, smart watches, mobile phones, tablets, game consoles, headphones, Nintendo Switch, etc.
GREAT ALTERNATIVE USB-C CHARGER: This compact USB C laptop charger is designed with a foldable plug for easy portability and convenient home/office and outdoor charging.
What you get: USB C Charger Add a free 6.6" USB-C to USB-C charging cable, compatible with Macbook Pro, Mac book Air, iPad Pro, it's more sturdy, super durable, tangle-free, with a lifespan of over 10000 Second-rate.
usb c charger for macbook,macbook usb c charger,usb c macbook adapter,usb c macbook power adapter
Shenzhen Waweis Technology Co., Ltd. , https://www.huaweishiadapter.com