The potential to exploit single-walled carbon nanotubes (SWNTs) in advanced electronics represents a continuing, major source of interest in these materials. However, scalable integration of SWNTs into circuits is challenging because of difficulties in controlling the geometries, spatial positions, and electronic properties of individual tubes. We have implemented solutions to some of these challenges to yield radio frequency (RF) SWNT analog electronic devices, such as narrow band amplifiers operating in the VHF frequency band with power gains as high as 14 dB. As a demonstration, we fabricated nanotube transistor radios, in which SWNT devices provide all of the key functions, including resonant antennas, fixed RF amplifiers, RF mixers, and audio amplifiers. These results represent important first steps to practical implementation of SWNTs in high-speed analog circuits. Comparison studies indicate certain performance advantages over silicon and capabilities that complement those in existing compound semiconductor technologies.

We consider the accuracy of measurements of the complex conductivity of superconducting films with a two-coil mutual inductance technique. We present a numerical analysis of the procedure by which we deduce the real and imaginary parts of the conductivity, σ=σ1−iσ2, of thin films from the in-phase and out-of-phase components of the mutual inductance of coaxial coils located on opposite sides of the film. The accuracy of the procedure is verified for the full ranges of film radii, thicknesses, and conductivities that are encountered for typical films of a wide variety of cuprate superconductors. We determine both experimentally and theoretically what effect flaws in the film would have on the accuracy of the measurement by examining the effects of holes located at various places in a superconducting film. The effect of capacitive coupling between the coils is measured and shown to be negligible when care is taken in grounding the drive and pickup coil circuits. The mutual inductance of the coils changes with temperature even with no sample present because the resistance of the coils changes and there is some thermal contraction. We describe a procedure for taking these effects into account.

A top-gated carbon nanotube (CNT) field-effect transistor (FET) was fabricated on a quartz substrate. We used a novel measurement approach and demonstrated for the first time frequency-independent performance of a CNT FET for frequencies as high as 23GHz. This observed maximum operating frequency represents a significant breakthrough in the realization of carbon nanotube-based electronics for high frequency applications.

The authors consider the suitability of carbon nanotubes for use in analog rf amplifiers, where the linearity of the device is critical. They show that in the limit of large electrostatic gate-channel capacitance, their theory predicts that an Ohmically contacted, ballistic carbon-nanotube-based field-effect transistor is inherently linear. While they have not achieved this limit in their experimental work, they compare the theory to experiment in the limit of small electrostatic gate-channel capacitance and find excellent agreement at virtually all bias conditions.

Operation of a carbon nanotube field effect transistor ͑FET͒ oscillator at a record frequency of 500 MHz is described. The FET was fabricated using a large parallel array of single-walled nanotubes grown by chemical vapor deposition on ST-quartz substrates. Matching of the gate capacitance with a series inductor enabled greater than unity net oscillator loop gain to be achieved at 500 MHz.