Friday, March 13, 2009

Super Broadband Devices

There seems to be a trend these days in designing very broadband devices that will operate over many communications bands so a single device can be used in many applications. Triquint recently developed their PowerBand family of amplifiers that feature high power (10-50 W) and good efficiency (typically 45-50%) over a wide band from 500 MHz to 3 GHz with a single device. They state that 2 to 4 Powerband devices can replace a typical line up of 6 to 12 devices. The have plans to extend the range of these devices to 6 GHz and improve the power levels by leveraging LDMOS and GaN technology (I believe the current devices are GaAs based).

Yesterday Analog Devices released a 14 bit RF digital to analog converter (DAC) that uses direct digital synthesis to convert signals from DC to 3.6 GHz. One device can handle up to 72 QAM channels with sample rates up to 2500 MPSP which is very impressive performance. It will enable wireless communications designers to use a single transmit-DAC architecture for multiple communications standards while eliminating an off-chip mixer and low-pass filter.

These 2 devices can pretty much make up a complete transmit chain that operates at about any frequency currently used for communications systems (maybe they can partner up). What other very broadband devices have you seen recently developed?

Wednesday, March 11, 2009

Treating Tumors with Microwave Ablation

More news from the "microwaves in applied science" front. A new minimally-invasive option for treating liver tumors, called microwave ablation, is now available at UC San Diego Medical Center and Moores UCSD Cancer Center, the only hospitals in the region to offer this technology to patients. “Microwave ablation causes the tumor to be quickly and precisely removed. If necessary, multiple tumors can be treated at the same time,” said Marquis Hart, MD, transplant surgeon at UC San Diego Medical Center. “This method appears to be more efficient than other ablation techniques which translates to better tumor destruction and less time for the patient under general anesthesia.”

To perform the procedure, Hart accesses the tumor through the skin, or through a small laparoscopic port or open incision. With ultrasound guidance or a computed tomography (CT) scan, the tumor is located and then pierced with a thin antenna which emits microwaves. This energy spins the water molecules in the tumor producing friction which causes heat. Temperatures above 60 degrees Celsius (140 degrees Fahrenheit) cause cellular death, usually within 10 minutes.

In addition to liver disease, microwave ablation has promising potential in the treatment of lung, kidney, and bone cancer. Studies using microwave or radio frequency ablation for the treatment of cancer has been in the works for several years. Apparently the studies were sucessful and the technology is going mainstream.

Sunday, March 8, 2009

The Nano Radio

This is not totally new news but a recent article in Scientific American has called some attention to it as researchers have built the world's tiniest radio out of a carbon nanotube. The tiny nanotube is placed between two electrodes and combines the roles of the major electrical components in a radio, including the tuner and amplifier. It can tune in to a radio signal and play the audio through an external speaker.

The nanotube radio works differently than a conventional radio that has an antenna, tuner, amplifier, and demodulator. A single carbon nanotube can tune in to a radio signal, amplify it, and demodulate it to get the audio encoded on the carrier radio wave. The nanotube starts vibrating in tune with a radio signal if the signal is at the same frequency as the nanotube’s natural resonance frequency. This can be controlled by the electric field that is placed on the nanotube so it can be tuned to the proper frequency. The first song played was appropriately Good Vibrations by the Beach Boys.
At the AMTA conference last year I saw some research on using nanotubes as antennas for miniature radios but the initial work showed they were not able to make them work very well at RF frequencies.

See and here the nanotube radio on Technology Review here.