Analog Predistortion Linearizer With Independently Tunable Gain and Phase Conversions for Ka-Band TWTA

Analog predistortion (APD) is an effective technique to improve the linearity of the traveling-wave tube amplifier (TWTA). This paper presents a novel APD linearizer with independently tunable gain and phase conversions. Based on symmetrical dual-branch vector synthetic topology, which avoids introducing the additional delay line, this linearizer achieves a simple circuit structure. Independent tuning of gain and phase conversions of this linearizer is realized by changing the bias voltages of the two branches. Theoretical analysis and tuning process of this linearizer are discussed in detail. Simulated and measured results are in a good agreement, and both of them verify that this linearizer has the independent tuning ability. Furthermore, a 250-W Ka-band TWTA is linearized by this linearizer, and the measurement results demonstrate the effectiveness of this linearizer in TWTA linearization.