Water Treatment Industry Pressure Gauge ZHOUSHAN JIAERLING METER CO.,LTD , https://www.zsjrlmeter.com
An adaptive algorithm unique to an innovative DPD linearization circuit
In wireless communication systems, achieving a balance between power amplifier (PA) linearity and efficiency is a critical challenge. Engineers are continuously seeking advanced digital predistortion (DPD) technologies that can enhance the performance of wideband RF PAs while maintaining high efficiency. This article explores various digital predistortion techniques and introduces an innovative adaptive algorithm designed for a novel DPD linearization circuit.
Volterra-based adaptive DPD circuits offer a promising solution by enabling both high linearity and efficiency in RF PAs. These circuits extend the linear operating range of the PA, reduce the crest factor, and improve power delivery without compromising signal integrity. They also help meet stringent spectral efficiency and modulation accuracy requirements, making them ideal for modern wireless applications.
The GC5322 transmitter solution from Texas Instruments integrates digital up-conversion, crest factor reduction, and DPD into a single, highly integrated ASSP. Fabricated using a 0.13-micron CMOS process, this chip supports a 30 MHz signal bandwidth and is "modulation-agnostic," meaning it can handle multiple standards like CDMA2000, WCDMA, TD-SCDMA, WiMAX, and LTE. It reduces peak-to-average power ratio (PAR) by up to 6 dB for 3G signals and improves adjacent channel power ratio (ACPR) by 4 dB for OFDM. The system can correct nonlinearities up to order 11 and manage PA storage effects of up to 200 ns, significantly improving ACPR and power efficiency—sometimes by more than 20 dB and 4 times respectively.
Efficient PAs are essential in base stations, where they account for about 30% of total system costs. As energy costs rise and environmental concerns grow, there's a strong push toward greener, more efficient technologies. With increasing demands for higher spectral efficiency and wider signal bandwidths, PA linearity has become a key design consideration for next-generation base stations.
Traditional analog and RF linearization techniques have been largely replaced by adaptive DPD, which offers better performance at lower cost. The growing computational power of DSPs and ASSPs has made digital pre-distortion increasingly viable. The GC5322 solution, with its real-time adaptive control, allows for flexible optimization across various RF architectures and modulation standards.
High PAR signals, such as those found in 3G CDMA and multi-carrier OFDM systems, require precise error vector magnitude (EVM) control. Non-constant envelope modulations, like QAM, demand high linearity from the PA, which is often limited. Linearization techniques like DPD help mitigate these issues, especially when used with advanced PA topologies like Doherty amplifiers.
While conventional class AB amplifiers operate at 5–10% efficiency, modern solutions using DPD and GaN or GaAs transistors can achieve nearly 50% efficiency. This improvement is crucial for reducing power consumption and operational costs in base stations.
Moving forward, we will explore the need for a highly accurate model in predistortion schemes, focusing on how memory effects and nonlinearities impact performance. Understanding these factors is essential for designing effective and robust DPD systems.