Matching Circuitry Research Articles

Computational Study of Spin-Torque Oscillator Interactions for Non-Boolean Computing Applications

We present a bottom-up approach for building non-Boolean signal processing devices from coupled spin-torque oscillators (STOs). We use micromagnetic simulations to study frequency-locking properties of electrically connected out-of plane magnetized STOs. After developing and verifying compact models for interacting STOs, we show that the frequency locking of STOs exhibits associative properties. Coupled STO networks therefore may be used as building blocks of non-Boolean pattern matching circuitry.

Integrated Memristor-MOS (M2) Sensor for Basic Pattern Matching Applications

This paper introduces an integrated sensor circuit based on an analog Memristor-MOS (M2) pattern matching building block that calculates the similarity/dissimilarity between two analog values. A new approach for a pulse-width modulation pixel image sensor compatible with the memristive-MOS matching structure is introduced allowing direct comparison between incoming and stored images. The pulsed-width encoded information from the pixels is forwarded to a matching circuitry that provides an anti-Gaussian-like comparison between the states of memristors. The non-volatile and multi-state memory characteristics of memristor, together with the related ability to be programmed at any one of the intermediate states between logic '1' and logic '0' brings us closer to the implementation of bio-machines that can eventually emulate human-like sensory functions.

An implanted 8-channel array coil for high-resolution macaque MRI at 3T.

An 8-channel receive coil array was constructed and implanted adjacent to the skull in a male rhesus monkey in order to improve the sensitivity of (functional) brain imaging. The permanent implant was part of an acrylic headpost assembly and only the coil element loop wires were implanted. The tuning, matching, and preamplifier circuitry was connected via a removable external assembly. Signal-to-noise ratio (SNR) and noise amplification for parallel imaging were compared to single-, 4-, and 8-channel external receive-only coils routinely used for macaque fMRI. In vivo measurements showed significantly improved SNR within the brain for the implanted versus the external coils. Within a region-of-interest covering the cerebral cortex, we observed a 5.4-, 3.6-fold, and 3.4-fold increase in SNR compared to the external single-, 4-, and 8-channel coils, respectively. In the center of the brain, the implanted array maintained a 2.4×, 2.5×, and 2.1× higher SNR, respectively compared to the external coils. The array performance was evaluated for anatomical, diffusion tensor and functional brain imaging. This study suggests that a stable implanted phased-array coil can be used in macaque MRI to substantially increase the spatial resolution for anatomical, diffusion tensor, and functional imaging.

A Calibration-Free Low-Cost Process-Compensated Temperature Sensor in 130 nm CMOS

A calibration-free low-cost CMOS integrated smart temperature sensor is presented that requires significantly less die area than previously published designs through the use of novel circuit technique and the 130 nm CMOS process. Uncalibrated sensor operation is achieved through the extensive use of analog dynamic element matching and chopper stabilization circuitry. A novel process-compensation circuit is presented that uses the correlation between pinch-base resistance and substrate bipolar <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BE</sub> temperature gradient. Accuracy mostly within the range of ±1°C was achieved using a die area of only 0.21 sq. mm. Prototype sensor performance was found to be limited by the low β characteristics of the substrate bipolar transistors implemented in the 130 nm CMOS process.

Superconducting IF biasing circuit for low-noise cryogenic applications

A planar superconducting circuit designed for use in low-noise cryogenic applications is presented. The circuit is a bias-T combined with a 4–8 GHz impedance matching circuitry, which employs entirely planar design with a novel layout. The proposed and tested circuitry is intended to be used with a SIS mixer and incorporates a double section transformer based on microstrip line technology with a total impedance transformation of 5:1 within the frequency band. One of the transformer sections employs a three-line coupled line, which also serves as a DC block capacitor. The microstrip lines were manufactured using superconducting Nb metallization, which provides a conduction loss-free solution at the operation temperature of 4 K. S-parameter measurements at 4 K temperature were performed and found to be in a good agreement with the simulations. The device measured return loss is better than −10 dB within the frequency band. Furthermore, the circuit was tested as a part of 385 – 500 GHz double sideband heterodyne SIS receiver demonstrating a flat noise temperature response of 80 – 90 K over the entire IF band of 4 – 8 GHz.

Aging and the depth of binocular rivalry suppression

Two experiments were designed to examine the effect of aging on the strength of binocular rivalry suppression. To produce rivalry, orthogonally oriented sine-wave luminance gratings were presented dichoptically. The observers were then required either to discriminate the spatial location of a probe spot presented to the dominant or suppressed eye's view or to detect the presence or absence of the probe. The observers in the younger and older age groups exhibited typical rivalry suppression for both tasks (i.e., the probe was more difficult to detect or discriminate when presented to the suppressed eye), but the magnitude of the suppression was significantly larger in the older observers. This increased suppression that accompanies aging can be explained by a reduction in the inhibition produced by the binocular matching circuitry of S. R. Lehky and R. Blake's (1991) model.

Broadband dual‐frequency spider‐shaped printed dipole antenna for WLAN applications

AbstractA novel broadband dual‐frequency spider‐shaped dipole antenna for 2.4/5.2 GHz wireless local area networks (WLAN) is proposed. The antenna consists of a double‐sided printed dipole, whose long arms and short center‐stubs can produce dual bands and lead to good impedance matching in a wide dual‐band without external matching circuitry. For the experimental study, excellent performance for operating frequencies across 2240–3260 MHz and 4700–5970 MHz bands has been observed. Good radiation characteristics of dipole‐like patterns, and 2.6‐ and 4.6‐dBi peak antenna gains for the lower and upper bands, respectively, have been obtained. And this antenna could be easily printed and integrated on the system circuit board for WLAN applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:917–919, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25041

Study of a uniplanar printed internal WWAN laptop computer antenna including user's hand effects

AbstractA uniplanar monopole antenna to be printed on a thin (0.4 mm) and small‐size FR4 substrate and capable of GSM850/900/1800/1900/UMTS penta‐band WWAN operation for thin‐profile laptop computer application is presented. The antenna is formed by a direct‐fed shorter radiating strip for upper‐band operation at about 1900 MHz and a coupled‐fed longer radiating strip which is also short‐circuited to the antenna ground for lower‐band operation at about 900 MHz. Note that the two radiating strips are fed using different excitation mechanisms. With the coupling excitation and short‐circuiting, which functions as an internal printed matching circuitry, the longer radiating strip can provide a wide dual‐resonant lower band at around 900 MHz for GSM850/900 operation. A wide upper band can also be generated at about 1900 MHz for the antenna to cover GSM1800/1900/UMTS operation. The antenna is studied in the article, and the user's hand effects on the performances of the antenna are analyzed. The obtained results are useful for the antenna employed in the laptop computer with a touch panel. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2341–2346, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24614

96‐Channel receive‐only head coil for 3 Tesla: Design optimization and evaluation

The benefits and challenges of highly parallel array coils for head imaging were investigated through the development of a 3T receive-only phased-array head coil with 96 receive elements constructed on a close-fitting helmet-shaped former. We evaluated several designs for the coil elements and matching circuitry, with particular attention to sources of signal-to-noise ratio (SNR) loss, including various sources of coil loading and coupling between the array elements. The SNR and noise amplification (g-factor) in accelerated imaging were quantitatively evaluated in phantom and human imaging and compared to a 32-channel array built on an identical helmet-shaped former and to a larger commercial 12-channel head coil. The 96-channel coil provided substantial SNR gains in the distal cortex compared to the 12- and 32-channel coils. The central SNR for the 96-channel coil was similar to the 32-channel coil for optimum SNR combination and 20% lower for root-sum-of-squares combination. There was a significant reduction in the maximum g-factor for 96 channels compared to 32; for example, the 96-channel maximum g-factor was 65% of the 32-channel value for acceleration rate 4. The performance of the array is demonstrated in highly accelerated brain images.

Cylindrical CPW-fed and CPS-fed slot antennas

Cylindrical antennas are needed in applications which require mounting on curved surfaces. This article presents two new designs of antennas printed on cylindrical substrates. The first antenna is a dual frequency coplanar waveguide (CPW)-fed double folded slot antenna operating at 5 and 7 GHz. This antenna is matched to the feed line without external matching circuitry and exhibits a gain of about 3.2 dBi. It has a bidirectional pattern in the E-plane and a more omnidirectional pattern in the H-plane. The second antenna is a coplanar strips (CPS)-fed folded slot antenna operating at 7 GHz. Its gain is about 2.56 dBi. The experimental and numerical results are provided for the return loss and radiation patterns with good agreement.

Low power and high gain current reuse LNA with modified input matching and inter-stage inductors

In this paper we present a fully integrated current reuse CMOS LNA (low noise amplifier) with modified input matching circuitry and inductive inter-stage architecture in 0.18μm CMOS technology. To reduce the large spiral inductors that actually require larger surface area for their fabrication, two parallel LC circuits are used with two small spiral on-chip inductors. Using cascode configuration equipped by parallel inter-stage LCs, we achieved lower power consumption with higher power gain. In this configuration we used two cascoded transistors to have a good output swing suitable for low voltage technology compared to other current reuse configurations. This configuration provides better input matching, lower noise figure and more reverse isolation which is vital in LNA design. Complete analytical simulation of the circuit results in center frequency of 5.5GHz, with 1.9dB NF, 50Ω input impedance, 1GHz 3dB power bandwidth, 20.5dB power gain (S21), high reverse isolation (S12)<−48dB, −18.5dB input matching (S11) and −21.3dB output matching (S22), while dissipating as low power as 2mW at 1.8V power supply.

Towards a microcoil for intracranial and intraductal MR microscopy.

Implantable RF-coils have enabled sub-mm resolution magnetic resonance images (MRI) of deep structures. Scaling down the size of RF coils has similarly provided a gain in signal-to-noise ratio in nuclear-magnetic-resonance spectroscopy. By combining both approaches we designed, fabricated, and imaged with an implantable microcoil catheter. While typical implantable catheters use a transverse magnetization, the axial magnetization of the microcoil provides improved sensitivity and allows visualization of the tissue beyond the distal end of the catheter. The microcoil catheter was designed with a diameter of 1 mm for future integration with intracranial devices, and for intraductal use in breast oncology. We modified the NMR-microcoil design to allow implantation of the RF coil, by winding the microcoil on medical-grade silicone tubing and incorporating leads on the catheter to connect circuit components. In order to achieve proper turn spacing, we coated copper wire with 25 microm of biocompatible polymer (Parylene C). Tuning and matching circuitry insured that the impedance of the RF coil was approximately 50 ohm at the operating frequency for 3-T proton MR applications. A duplexer was used to enable use of the microcoil catheter as a transceiver. Experimental verification of the coil design was achieved through ex vivo imaging of neural tissue. As expected, the microcoil catheter provided microscale images with 20-microm in-plane-resolution and 170-microm-thick slices. While 3-T MRI typically provides 1 to 30 voxels per-cubic-millimeter, in this paper we report that the MRI microcoil can provide hundreds, and even thousands of voxels in the same volume.

Demonstration of a 311-GHz Fundamental Oscillator Using InP HBT Technology

In this paper, a sub-millimeter-wave HBT oscillator is reported. The oscillator uses a single-emitter 0.3 m15 m InP HBT device with maximum frequency of oscillation greater than 500 GHz. The passive components of the oscillator are realized in a two metal process with benzocyclobutene used as the primary transmission line dielectric. The oscillator is implemented in a common base topology due to its inherent instability. The design includes an on-chip resonator, output matching circuitry, and injection locking port. A free-running frequency of 311.6 GHz has been measured by down-converting the signal. Additionally, injection locking has been successfully demonstrated with up to 17.8 dB of injection-locking gain. This is the first fundamental HBT oscillator operating above 300 GHz.

Aging and the depth of binocular rivalry suppression.

Two experiments were designed to examine the effect of aging on the strength of binocular rivalry suppression. To produce rivalry, orthogonally oriented sine-wave luminance gratings were presented dichoptically. The observers were then required either to discriminate the spatial location of a probe spot presented to the dominant or suppressed eye's view or to detect the presence or absence of the probe. The observers in the younger and older age groups exhibited typical rivalry suppression for both tasks (i.e., the probe was more difficult to detect or discriminate when presented to the suppressed eye), but the magnitude of the suppression was significantly larger in the older observers. This increased suppression that accompanies aging can be explained by a reduction in the inhibition produced by the binocular matching circuitry of S. R. Lehky and R. Blake's (1991) model.

A 5.8-GHz ETC Transceiver Using SiGe-BiCMOS

A fully integrated 5.8 GHz ETC transceiver LSI has been developed. The transceiver consists of LNA, down-conversion MIX, ASK detector, ASK modulator, DA VCO, and ΔΣ-fractional-N PLL. The features of the transceiver are integrated matching circuitry for LNA input and for DA output, ASK modulator with VGA for local signal control to avoid local leakage and to keep suitable modulation index, and LO circuitry consisting of ΔΣ-fractional-N PLL and interference-robust oo-shape inductor VCO to diminish magnetic coupling from any other circuitry. Use of these techniques enabled realization of the input and output VSWR of less than 1.25, modulation index of over 95%, and enough qualified TX signals. This transceiver was manufactured by 1P3M SiGe-BiCMOS process with 47 GHz cut-off frequency.

Optimum dual‐resonant impedance matching of coupling element based mobile terminal antenna structures

AbstractThis article presents a theoretical study on optimum dual‐resonant impedance matching of coupling element based mobile terminal antenna structures. First, optimum tuning of the system of two series‐resonant circuits connected to each other with an ideal impedance transformer and an impedance inverter is studied. Simple, explicit equations are derived for optimum circuit parameters of the resonator system. After this, design rules are presented for a practical discrete‐component realization of a matching circuitry specifically optimized for nonresonant antenna structures. Special emphasis has been put on minimizing the complexity of the matching network. Discussion is also given on equivalent circuit modeling of the combination of chassis and a coupling element. The presented matching network design methodology is shown to work well when applied with a realistic coupling element based mobile terminal antenna structure. The results of this article also indicate that the combination of the chassis of a mobile terminal and a simple coupling element can be with a good enough accuracy approximated as a series‐RLC equivalent circuit. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2472–2477, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22762

A coupling element‐based quad‐band antenna structure for mobile terminals

AbstractA novel internal coupling element‐based antenna structure for quad‐band mobile terminals is presented. The antenna structure comprises of two nonresonant coupling elements, a multi‐resonant matching circuitry, and the chassis of the mobile terminal. The coupling elements occupy an extremely low volume of only 0.7 cm3, and they have a very low profile of only 4 mm. Despite of the low volume and low profile of the antenna structure, it can fulfill the bandwidth requirements of the GSM850/900 and GSM1800/PCS1900 systems with sufficiently high efficiency, thus making it a promising antenna candidate for future mobile terminals. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1277–1282, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22463

Improvements in the Design of Matrix Distributed Amplifiers

A simple method for the gain improvement of matrix distributed amplifiers is presented. The method is based on modifying the central transmission line of the matrix amplifier without any changes in the input and output transmission lines. In the new method the termination impedances in the central transmission line are modified and the transmission line is replaced by an impedance matching circuitry. It has been shown that the new method can significantly improve the gain while preserving the input and output return losses of the amplifier.

Covert dual-band wearable button antenna

A novel dual-band antenna for wearable WLAN computing applications is introduced. This antenna comprises three discs and a coaxial post. Its appearance is of a standard metal button of the type used in denim jeans. The antenna is easily disguised and less sensitive to clothing than printed patches, which use the textile fabric as a substrate or superstrate. The antenna requires no external matching circuitry and operates at 2400 and 5200 MHz. The radiation patterns are omnidirectional around the central post of the antenna.

Voltage-mode high-Q band-pass filters and oscillators employing single CDBA and minimum number of components

In this paper, voltage-mode second order high-Q band pass filters and oscillators which employ only single current differencing buffered amplifier (CDBA) as the active component are proposed. One of the four filter circuits and two of the four oscillators described have minimum passive component count properties, without using the internal pole of the active element. These BP filters can be easily cascaded without any recourse to impedance matching circuitry. The circuits have been analysed theoretically, simulated and experimentally tested in a laboratory. It is shown that the results of simulations and experimental work are in agreement with theoretical predictions.