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Engineers at the University of Michigan have built the first millimeter-scale stand-alone device that meets Bluetooth Low Energy (BLE) specifications. "Consuming just 0.6 milliwatts during transmission, it would broadcast for 11 years using a typical 5.8-mm coin battery," reports IEEE Spectrum. "Such a millimeter-scale BLE radio would allow these ant-sized sensors to communicate with ordinary equipment, even a smartphone." From the report: The transmitter chip, which debuted last month at IEEE International Solid-State Circuits Conference, had to solve two problems. The first is power consumption, and the second is the size of the antenna. An ordinary transmitter circuit requires a tunable RF oscillator to generate the frequency, a power amplifier to boost its amplitude, and an antenna to radiate the signal. The Michigan team combined the oscillator and the antenna in a way that made the amplifier unnecessary. They called their invention a power oscillator. The key part of an oscillator is the resonant tank circuit: an inductor and a capacitor. Energy sloshes back and forth between the inductor's magnetic field and the capacitor's electric field at a resonant frequency determined by the capacitance and inductance. In the new circuit, the team used the antenna itself as the inductor in the resonant tank. Because it was acting as an inductor, the antenna radiated using changing magnetic field instead of an electric field; that meant it could be more compact.

However, size wasn't the only thing. Quality factor, or Q, is a dimensionless quantity that basically says how efficient your resonator is. As a 14-mm long loop of conductor, the antenna was considerably larger than an on-chip inductor for a millimeter-scale radio could be. That led to a Q was that was about five times what an on-chip inductor would deliver. Though it was a much more efficient solution, in order to meet BLE specifications, the team needed a better way to power the power oscillator. Their solution was to build an on-chip transformer into the circuit that supplies power to it. The transformer looks like two nested coils. One coil is attached to the supply voltage end of the oscillator circuit, and the other is attached to ground side. Pumping the transformer at a frequency twice that of the power amplifier wound up efficiently boosting the flow of power to the antenna.

Researchers at Google, the University of Massachusetts at Amherst, and the University of California Santa Barbara has solved one of the biggest limitations with quantum computing: all the control and readout circuits of quantum computer systems must be at room temperature, while their superconducting qubits live in a cryogenic enclosure at less than 1 kelvin. "For today's sub-100-qubit systems, there's enough space for specialized RF cabling to come in and out of the enclosure," reports IEEE Spectrum. "But to scale up to the million-qubit systems needed to do really cool stuff, there just won't be enough room."

At the IEEE International Solid-State Circuits Conference in San Francisco last month, the researchers reported making a key control circuit in CMOS that will work at cryogenic temperatures. They described it as "a high-performance, low-power pulse modulator needed to program the qubits." From the report: "The current approach is OK for now," says Joseph Bardin, a University of Massachusetts at Amherst associate professor of electrical and computer engineering who designed the IC while on sabbatical at Google. "But it's not scalable to a million qubits." For Google's 72-qubit quantum processor there are already 168 coaxial cables going into the refrigerator and connecting to the 10-millikelvin quantum processor. The pulse modulator IC Bardin worked on is used to encode quantum states on a qubit in order to execute a program. Quantum computers get their parallelizing power because qubits don't have to be just 0 or 1, like the bits in an ordinary computer. Instead, they can be a mix of those states. The pulse modulator uses a specific set of RF frequencies to produce that mix.

"The biggest challenge is heat dissipation," explains Bardin. The qubits are at 10 millikelvins, but the control circuits, which necessarily throw off heat, can't be held that low. The researchers aimed for 4 K for the control IC. "However, at 4 K, thermodynamics limits the efficiency of cooling. The best you're going to get is about 1 percent efficiency. In practice it's worse." So the power dissipated by the electronics per qubit had to be only in the milliwatt range. That power constraint had to be balanced with the need for control accuracy, Bardin says. This was complicated by how differently CMOS transistors behave at 4 k, which is a more than 200 degrees below what silicon foundries' simulation models can deal with. Bardin and the Google team managed to design the IC in a way that compensates for these problems and achieves the balance between power consumption and performance. The resulting IC consumed less than 2 mW, yet it was able to put a qubit through its paces in testing.

EmagGeek writes "Attempts by the US Defense Advanced Research Projects Agency (DARPA) to create cybernetic insects (hybrids of biological and electronic 'bugs') have yielded ultra-low power radios to control the bugs' flight and a method of powering those circuits by harvesting energy, according to research that will be reported this week at the IEEE International Solid-State Circuits Conference. 'Electrodes and a control chip are inserted into a moth during its pupal stage. When the moth emerges the electrodes stimulate its muscles to control its flight. I expect a run on bug zappers any day."

News for nerds writes "The ISSCC 2005, the "Chip Olympics", is over and David T. Wang at Real World Technologies put a very objective review of the CELL processor (the slides for the briefing are also available), covering all the aspects disclosed at the conference. Besides the much touted 256 GFlops single-precision floating point performance the CELL processor has 25-30 GFlops in double-precision, which is useful enough for scientific computation. Linus seems interested in CELL, too."