A miniature high gain and broadband MMIC distributed amplifier

A new miniature MMIC distributed amplifier, which combines conventional distributed amplifier (CDA) to extend wider bandwidth and a single-stage cascade amplifier (SSCA) as a gain stage for high gain over several octaves of bandwidth (called CDA-SSCA) is presented in this paper. The low pass filter (LPF) configuration is adopted between the CDA and SSCA while resistive terminations are used in the biasing circuitry to provide broadband matching. The measured small signal gain is 22±1.5 dB from 0.5 to 27 GHz with a chip size of 1.5 × 1 mm². Another two broadband distributed amplifiers are also designed for comparison and with the same chip size. One is cascaded the two single-stage distributed amplifiers, called two-cascaded single-stage distributed amplifier (2-CSSDA), and the other is a CDA cascaded with a CSSDA, called (CDA-CSSDA). This CDA-SSCA produces a significantly higher gain than the other two designs 2-CSSDA and CSD-CSSDA within the same bandwidth. The flat group delay of this design also proves the feasibility for digital optical communication applications.