Research at Photonics Laboratories
(High-Speed Electronics Circuit and Device - 3)
8 × 8 Switch Matrix IC using InP HEMTs for 10-Gbit/s
Systems
Electrical switches are key devices for broadband
between ITLs (from 784 to 196). In addition, we used InP
communications systems and measurement systems. A critical
high electron mobility transistors (HEMTs) as the cold FETs.
issue to making a large-capacity switch is how to increase the
Compared with silicon (Si)- or GaAs-based FETs, these have
port count without increasing power consumption. A cold-
less than half the ON-resistance OFF-capacitance product,
FET switch is very attractive since it dissipates virtually
which allows us to build a wideband (dc-13GHz) switch. Figure
zero power. However, no switch matrix IC using cold FETs
2 shows the eight output waveforms from the IC (Out#1∼
with port counts of over 4 × 4 has been reported to date.
#8) when eight 10-Gbit/s data signals were simultaneously
This is because a conventional n × n switch matrix consists
input to In#1∼#8. Clear eye openings are apparent for all
of as many as 2n 1 × n switches and n2 interconnection
eight outputs. Error-free operation up to 12.5 Gbit/s was
transmission lines (ITLs) between the switches.
confirmed.
Figure 1 shows the 8 × 8 switch IC we developed. Its
2
The switch IC will likely be extensively used not only for
area (0.4 mm ) is only about 6% the area of the conventional
10-Gbit/s systems but also for wideband wireless systems
configuration, thanks to the use of a novel size-reduction
and measurement systems, since it is an analog switch with
technique that requires half number of 1 × 8 switches (from
virtually zero power dissipation.
16 to 8), fewer ITLs (from 64 to 40) and fewer crossovers
In#4
In#3
In#2
In#1
1 × 8 SW
1 × 8 SW
1 × 8 SW
1 × 8 SW
Out#1
（from In#8）
Out#1
Out#2
Out#3
Out#2
（from In#7）
Out#4
Out#5
Out#6
1 × 8 SW
1 × 8 SW
1 × 8 SW
1 × 8 SW
In#5
In#6
In#7
In#8
Out#3
（from In#6）
Out#7
Out#8
Out#4
（from In#5）
(a) Configuration of 8 x 8 switch matrix
In#4
In#3
In#2
Out#5
（from In#4）
In#1
Out#1
Out#6
（from In#3）
Out#2
Out#3
Out#4
1 × 8 SW
Out#7
（from In#2）
Out#5
Out#6
Out#7
Out#8
（from In#1）
Out#8
In#5
In#6
In#7
In#8
(b) 8 × 8 switch matrix IC (0.98 mm × 0.41 mm)
Fig. 1 Configuration and microphotograph of 8 × 8 switch
matrix IC.
Fig. 2 Output waveforms when eight 10-Gbit/s data signals
are input. 500 mV/div., 50 ps/div.
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