Constant Linearity Variable Gain Traveling Wave Amplifier MMIC for 1 to 26.5 GHz Applications

This paper describes the design and test results of a constant linearity variable gain traveling wave amplifier (VGTWA) suitable for 1 to 26.5GHz applications. The constant linearity VGTWA consists of variable feedback cascode stages, input artificial transmission line, output artificial transmission line, and a drain DC biasing network. The VGTWA was fabricated by the Avago´s 0.25mum enhancement mode PHEMT process thus requires only a positive supply for bias and control. The constant linearity VGTWA exhibits 9 +/- 2 dB of maximum small signal gain between 1 and 26.5GHz frequencies with 15dB gain control. The TGTWA exhibits 14dBm minimum output 3^rd order intercept point over the gain controlling range. The VGTWA also exhibits constant input/output return losses over the gain controlling conditions