Looking to bring lighter, more powerful and less expensive systems for various applications such as communications, radar or guidance systems, DARPA said this week it had recently demonstrated an all-silicon, microchip-sized system on a chip that runs at 94 GHz.
DARPA claims that this chip is the first time a silicon-only package has achieved such a high frequency, which falls in the millimeter-wave range.
"What normally would require multiple circuit boards, separate metal shielded assemblies and numerous I/O cables we can now miniaturize onto one silicon chip about half the size of an adult's thumbnail," said Dev Palmer, DARPA program manager in a statement. "This accomplishment opens the door for co-designing digital CMOS [complementary metal oxide semiconductors] and millimeter-wave capabilities as an integrated system on an all-silicon chip, which should also make possible new design architectures for future military [wireless] systems."
The all-silicon system on a chip transmitter was built by Northrop Grumman Aerospace Systems and uses a digitally assisted power amplifier that adapts amplifier performance characteristics to changing signal requirements. This capability according to DARPA allows for simultaneous optimization of efficiency and linearity — a key goal of all transmitters and power amplifiers designed to quickly deliver large amounts of data.
Palmer noted the package can support a range of modulation formats, so it's possible to communicate to multiple systems using different waveforms from a single silicon chip.
DARPA stated that many existing compact, high-data-rate millimeter-wave wireless communications systems use integrated circuits made with gallium arsenide (GaAs) or gallium nitride (GaN).
"These circuits provide high power and efficiency in small packages but are costly to produce and difficult to integrate with silicon electronics that provide most other radio functions. Silicon integrated circuits are less expensive to manufacture in volume than those with gallium compounds but until now have not demonstrated sufficient power output and efficiency at millimeter-wave frequencies used for communications and many other military applications," DARPA stated.
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