一种行波管用毫米波射频预失真线性化器

A Millimeter-Wave RF Predistortion Linearizer for Travelling Wave Tube Amplifier

射频预失真是提高功率放大器线性度的一种有效手段,精确补偿放大器的非线性失真需保证幅度和相位补偿同时满足要求.针对Ka波段行波管放大器的线性化,提出一种新型射频预失真电路.该电路由前置、后置电平调节模块和基于矢量合成技术的非线性信号产生模块构成.改变两电平调节模块的增益,可实现补偿区间的调节;改变非线性信号产生模块中两支路的偏置电压,可实现预失真补偿量调节及幅度/相位的独立调节.将实际电路与配用Ka行波管联测,在输出功率回退6 d B时,行波管三阶互调系数提高约11.5 d Bc.

The RF predistortion is an effective m ethod to im prove the linearity of High Power A m plifier（ HPA）.T o obtain a better linearity of the HPA,accurate am plitude and phase com pensation are required. A novel RF predistortion circuit is proposed for the linearization of a K a-band T ravelling W ave T ube A m plifier（ T W T A）,which consisted of a prepositive V ariable G ain A m plifier（ V G A）,a post V G A and a nonlinear signal generating m odule based on vector synthesis technique. C hanging the gain of the two V G A s can realize the adjustm ent of the com pensation range. Reasonably changing the bias voltages of the two branches in nonlinear generating m odule can adjust the com pensation am ount and can also independently regulate the am plitude or phase characteristic. T he T hird O rder Interm odulation（ TOI） of a Ka-band TWTA is improved by 11. 5 d B at 6d B output power back-off owing to the proposed RF predistortion linearizer.