A W-band Diode-Based Analog Predistortion Linearizer for Traveling Wave Tube Amplifiers

In this paper, an analog predistortion (APD) linearizer based on Schottky barrier diode (SBD) is proposed to improve the nonlinear characteristics of W-band traveling wave tube power amplifier (TWTA). Different from the low-frequency linearizer, the design considers the effects of cavity structure and the high frequency parasitic parameters of the physical structure of SBD by establishing three-dimensional electromagnetic simulation model (3D EM Model). A reflection type APD linearizer consisting of a 90 degrees waveguide 3dB hybrid and two SBDs is developed and tested. By applying different DC bias of the two SBDs, the gain and phase of the presented APD linearizer can be tuned in a wide range. The gain expansion is more than 5.9 dB and the phase expansion is over 26.5 degrees in the frequency 92.5-97.5GHz.