Low noise high-gain distributed preamplifiers using cascaded single stage distributed amplifier configurations

In this paper 2-10 GHz hybrid-distributed preamplifiers using two and three cascaded single stage distributed amplifiers are demonstrated. These ampli fiers produce available power gains significantly higher than conventional distributed preamplifiers using the same number of active devices. Simulati on results show the advantage of the proposed preamplifier over the convent ional one. Measured results of the two realised configurations of preamplif iers using two and three cascaded single stage distributed amplifiers are p resented. Each configuration shows that the available power gain can be inc reased by increasing interstage characteristic impedance of the cascaded si ngle stage distributed amplifiers. The measured available power gain for tw o stages shows an improvement from 18 dB to 20 dB, and for three stages an improvement from 26 dB to 31 dB across the 2-10 GHz frequency band, as the inter-stage characteristic impedance is increased from low to high level. I nput and output return losses better than -10 dB, and input-output isolatio n better than -55 dB at the beginning of the band and better than -45 dB at the end are achieved. This approach also provides a good measured noise fi gure performance of an average of 4 dB across the 2-10 GHz frequency band f or both two and three cascaded stages. The group delay of both cascaded amp lifiers are measured. Its Rat performance proves the viability of this appr oach which is suitable for digital optical communication and pulse applicat ions.