Fully Integrated Efficient and Wideband Distributed Amplifier Employing Dual-Feed Output Stage With Active Input Split-Stage in 0.13μm CMOS

This work presents the analysis, design, and implementation of an efficient and wideband active-split dual-feed distributed amplifier (AS-DFDA) in
$0.13~\mu \text{m}$
CMOS technology. It consists of a dual-feed (DF) output stage with a passive combiner and an active-split (AS) input stage. The dual-feed stage is used to enhance the gain and output power of the proposed AS-DFDA by utilising both the forward and reverse gains of a conventional distributed topology. The DF stage requires an in-phase equi-amplitude signals feeding the DF gate lines from both sides which is accomplished by an active-split stage based on the split drain-line topology providing a wideband input match along with the extra leaverage in gain. An external capacitance in series with the DF stage devices is deployed to increase the cut-off frequency of the dual-feed gate lines. Further, the interstage lines are terminated with idle-line terminations on both ends to target flat gain. The amplified signal from DF stage is combined through an output impedance matched direct passive combiner. The measured results show a 13–10 dB gain from 4–22 GHz and output return loss of 6dB over the entire bandwidth. The measured output saturated power,
$P_{SAT}$
, of 10.6 dBm with peak power added efficiency (PAE) of 15.1% is acheived at 5 GHz while a minimum peak PAE of 9% is obtained over the entire bandwidth. The AS-DFDA has a noise figure of 4–6 dB and occupies an active area of only
$0.45\,\text {mm}^{2}$
, respectively.