Frequency hopping is a best solution to find the free RF/Channel band available in the present environment where RF frequency bands are mostly occupied for cellular to WiFi to Zigbee to traditional analog transmission. To hopp from one band to other, very good frequency filtering is required. Researchers at MIT’s Microsystems Technology Laboratory (MTL) have developed a new method for manufacturing effective filters that should improve their performance while enabling 14 times as many of them to be crammed on a single chip.
Here the researchers Dana Weinstein and Laura Popa have converted the radio signal to an acoustic signal and then convert it back to an electrical signal. The filtering of acoustic signal is done using acoustic resonators.
Dana Weinstein says “Acoustic wavelengths are much smaller than electromagnetic wavelengths, So for a given frequency, my mechanical resonator is going to be much smaller.”
Weinstein and Popa have used semiconductor material Gallium nitride to make the capacitor of the resonator circuit, which can be done on-chip.
Thomas Kazior, a principal engineering fellow at Raytheon says “We’re talking about making filters that are directly integrated onto, say, a receiver chip, because the little resonator devices are literally the size of a transistor,” he says. “These are all on a tiny scale.”
“They can help with the cost problem because these resonator-type structures almost come for free,” Kazior adds. “Building them is part of the semiconductor fabrication process, using pretty much the existing fabrication steps that you’re using to build the transistor and the rest of the circuits. You just may need to add one, or two at the most, additional steps — out of 100 or more steps."