T. Seshita et al., A 20-GHZ 8-BIT MULTIPLEXER IC IMPLEMENTED WITH 0.5-MU-M WNX W-GATE GAAS-MESFETS/, IEEE journal of solid-state circuits, 29(12), 1994, pp. 1583-1588
An ultrahigh-speed 8 bit multiplexer (MUX) has been developed for futu
re-generation optical-fiber communication systems having a data rate o
f 20 Gb/s, This IC was fabricated using a 0.5 mu m WNx/W-gate GaAs MES
FET process based on optical lithography, ion implantation, and furnac
e annealing for good reproducibility and high throughput. The WNx/W bi
layer gate has a low sheet resistance, improving the circuit high freq
uency performance, To attain 20 GHz operation, advanced circuit techni
ques for the source-coupled FET logic(SCFL) were introduced, A cross-c
oupled source-follower (CCSF) was developed mainly for the highest spe
ed buffers to enhance the bandwidth. The first-stage T-type hip-hop wa
s designed with optimization techniques and operated up to 21.1 GHz.