Digital Equalization System for Ka-Band Traveling Wave Tube Power Amplifiers

The demands for equalization accuracy in traveling wave tube power amplifiers (TWTAs) are increasingly stringent, and traditional analog equalizers are no longer sufficient. Furthermore, the low level of digitization in TWTAs makes the direct application of digital equalization techniques difficult. This study designs a digital equalizer system for Ka-band TWTAs that controls high-precision digital step attenuators (DSAs). By processing the RF link, the dynamic analog power signal was converted into a digital square wave, and digital equalization control was achieved using an STM32F103 microcontroller (STMicroelectronics, Geneva, Switzerland; Origin: Taiwan, China). Simulation and experimental results show that the system operates stably within the input dynamic power range of −20 to 0 dBm, with an overall control delay of approximately 2 ms, a frequency measurement error of less than 0.02%, and an equalization accuracy better than 0.25 dB. This work addresses the critical interface bottleneck between high-frequency analog TWT chains and digital control circuits, offering a reusable engineering solution for the digital upgrade of TWTA products.