Analysis of the performance of four-cascaded single-stage distributed amplifiers

In this paper, the analysis, design, and implementation of a hybrid broad-band distributed amplifier based on four-cascaded single-stage distributed amplifiers (4-CSSDAs) is demonstrated. The available gain produced by this amplifier is significantly higher than conventional distributed amplifiers (CDAs) using the same number of active devices. Simulation results for two versions of the 4-CSSDA are demonstrated, one with low interstage characteristic impedance (Z(oint)) and the other with high Z(oint). Simulation results show a number of advantages of the proposed amplifier over the CDA, in particular, that the available gain can be increased by increasing the Z(oint) Of the amplifier stages. Simulation predicts that gains approaching 50 dB could be achieved by appropriate design modification. Measured results for implementation of the two versions of the 4-CSSDA are reported. These show excellent performance with high gain, good gain flatness, input and output matching, flat group delays, and a low noise figure across a 1-10-GHz bandwidth. The amplifier configuration achieved a measured wide-band performance (0.8-10.8 GHz) with up to 39+-/-2-dB flat gain using discrete packaged active devices.