William F. Andress

Palm NMR and 1-Chip NMR

In our earlier work, we developed a 2-kg NMR system, which was 60 X lighter, 40× smaller, yet 60× more spin-mass sensitive than a 120-kg state-of-the-art commercial benchtop system. Here we report on two new nuclear magnetic resonance (NMR) systems that represent further orders-of-magnitude size reduction and lab-on-a-chip capability. The first system, which weighs 0.1 kg and can be held in the palm of a hand, is the smallest NMR system ever built, and is 1200× lighter, 1200× smaller, yet 150× more spin-mass sensitive than the commercial system. It is enabled by combining the physics of NMR with a CMOS RF transceiver. The second system, which even integrates a sample coil, directly interfaces the CMOS chip with a sample for lab-on-a-chip operation. The two systems detect biological objects such as avidin, human chorionic gonadotropin, and human bladder cancer cells.

Ultra-subwavelength two-dimensional plasmonic circuits.

We report electronics regime (GHz) two-dimensional (2D) plasmonic circuits, which locally and nonresonantly interface with electronics, and thus offer to electronics the benefits of their ultrasubwavelength confinement, with up to 440,000-fold mode-area reduction. By shaping the geometry of 2D plasmonic media 80 nm beneath an unpatterned metallic gate, plasmons are routed freely into various types of reflections and interferences, leading to a range of plasmonic circuits, e.g., plasmonic crystals and plasmonic-electromagnetic interferometers, offering new avenues for electronics.

Standing wave oscillators utilizing wave-adaptive tapered transmission lines

In this paper, we introduce a novel standing wave oscillator (SWO) utilizing standing-wave-adaptive tapered transmission lines. This structure enhances Q and lowers phase noise through loss-reducing shaping of the transmission line, such that it is adapted to the position-dependent amplitudes of standing waves. Measurements validate the advantages of the proposed technique. The phase noise of a MOS SWO with the tapered line is 5-10 dB less than that of a uniform-line MOS SWO over a wide range of offset frequencies, centered about 15 GHz. Demonstrating a valuable exploitation of standing wave properties, the novel design concept boosts the potential for the emergence of standing wave oscillators as a useful alternative to the traditional lumped LC oscillator.

A circular standing wave oscillator

A circular standing wave oscillator that generates sinusoids by forming standing waves on a ring transmission line is presented. Incorporating an even-mode suppression technique, a 10 GHz prototype realized in a SiGe bipolar technology has a phase noise of -110 dBc/Hz at 1 MHz offset with a 1.95 mA current drawn from 1.5 V.

Recent developments in standing-wave oscillator design: review

The paper summarizes the most recent advances in wave-based oscillator design, reviewing various manifestations of the traveling-wave oscillator and the standing-wave oscillator. We then review and analyze our latest development of standing-wave oscillator design utilizing wave-adaptive tapered transmission lines (Andress, W. and Ham, D., IEEE VLSI Symp., 2004). This structure lowers phase noise through loss-reducing shaping of the transmission line, such that it is adapted to the position-dependent standing wave amplitudes. Demonstrating the benefits of standing-wave-based operations, this novel design concept boosts the potential for the emergence of standing-wave oscillators as a useful alternative to the traditional LC oscillator.

Gigahertz surface acoustic wave generation on ZnO thin films deposited by radio frequency magnetron sputtering on III-V semiconductor substrates

The authors demonstrate 1.6GHz surface acoustic wave (SAW) generation using interdigital transducers patterned by e-beam lithography on a thin ZnO piezoelectric film deposited on an InP substrate. The highly oriented, dense, and fine-grain ZnO film with high resistivity was deposited by radio frequency magnetron sputtering and was characterized by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and a four-point probe station. The acoustic wavelength of the 1.6GHz SAW generated by exciting the interdigital transducer on ZnO∕InP with a microwave signal is 1.6μm. This SAW filter device could be monolithically integrated with optoelectronic devices, opening new opportunities to use SAWs for applications such as gigahertz-frequency filters on optoelectronic devices and novel widely tunable quantum cascade lasers.

Palm NMR and one-chip NMR

Nuclear magnetic resonance, or NMR, is the energy exchange between an RF magnetic field and an atomic nucleus such as a hydrogen proton, which is a tiny bar magnet due to its spin. NMR has a broad array of powerful applications, including: biomolecule sensing (e.g., cancer marker detection), medical imaging, and oil detection. NMR instruments, however, are bulky, heavy, and expensive, and remain as specialized equipment in hospitals, industry, and laboratories. An NMR system consists of a magnet, a sample coil, and an RF transceiver, where the magnet is by far the largest component. As a larger-sized magnet yields a stronger NMR signal even for the same field strength, large magnets are used, hence the bulky size.

Two-path solid-state interferometry using ultra-subwavelength two-dimensional plasmonic waves

We report an on-chip solid-state Mach-Zehnder interferometer operating on two-dimensional (2D) plasmonic waves at microwave frequencies. Two plasmonic paths are defined with GaAs/AlGaAs 2D electron gas 80 nm below a metallic gate. The gated 2D plasmonic waves achieve a velocity of ∼c/300 (c: free-space light speed). Due to this ultra-subwavelength confinement, the resolution of the 2D plasmonic interferometer is two orders of magnitude higher than that of its electromagnetic counterpart at a given frequency. This gigahertz proof-of-concept at cryogenic temperatures can be scaled to the terahertz–infrared range for room temperature operation, while maintaining the benefits of ultra-subwavelength confinement.

Surpassing Tradeoffs by Separation: Examples in Frequency Generation Circuits

We review three examples (two PLLs [Crowley, 1979; Woo et al.] and one on-chip transmission-line resonator [Andress and Ham, 2005] ) of design tradeoffs which can in fact be circumvented; the key in each case is that the parameters that seem to trade off with each other are actually separated in time or space. This paper is an attempt to present these designs in such a way that this common approach can hopefully be applied to other circuits.

Surpassing Tradeoffs by Separation: Examples in Transmission Line Resonators, Phase-Locked Loops, and Analog-to-Digital Converters

We review three examples (an on-chip transmission line resonator [1], a phase-locked loop [2], and an analog-to-digital converter [3]) of design tradeoffs which can in fact be circumvented; the key in each case is that the parameters that seem to trade off with each other are actually separated in time or space. This paper is an attempt to present these designs in such a way that this common approach can hopefully be applied to other circuits. We note reader that this paper is not a new contribution, but a review in which we highlight the common theme from our published works [1-3]. We published a similar paper [4], which, however, used only two examples from [1] and [2]. With the newly added content from [3] in the list of our examples, the present paper offers an expanded scope.