About
92
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Introduction
Leader of the NRAO Integrated Receiver Development Group, specializing in the creation of compact analog-digital-photonic front-ends for radio astronomy.
Current institution
Additional affiliations
June 1999 - May 2003
May 2003 - present
May 1996 - May 1998
Lockheed Martin Federal Systems
Position
- Associate Programmer
Education
June 1999 - June 2003
June 1995 - June 1999
Publications
Publications (92)
This invaluable resource introduces progressive techniques for the creation of sophisticated reflectionless filter topologies that have identically zero reflection coefficient at all frequencies. Practical implementations are discussed along with their advantages when compared to classical absorptive filters and their benefits in real-world systems...
We report on the development of a prototype integrated receiver front-end
that combines all conversions from RF to baseband, from analog to digital, and
from copper to fiber into one compact assembly, with the necessary gain and
stability suitable for radio astronomy applications. The emphasis in this
article is on a novel digital data link over op...
An analytical method for the visualization and prediction of trapped-mode
resonances based on the dimensions of a dispersive microwave network is
described. The method as explained is intuitive, easy to implement, and has
proven itself to be a useful tool in the avoidance of problems associated with
trapped modes prior to fabrication, as well as to...
In this paper we present a novel class of compact orthomode transducers which
use digital calibration to synthesize the desired polarization vectors while
maintaining high isolation and minimizing mass and volume. These digital
orthomode transducers consist of an arbitrary number of planar probes in a
circular waveguide, each of which is connected...
Provides society information that may include news, reviews or technical notes that should be of interest to practitioners and researchers.
We report on the development of millimeter-wave, lumped-element reflectionless filters using an advanced thin-film fabrication process. Based on previously demonstrated circuit topologies capable of achieving 50{\Omega} impedance match at all frequencies, these circuits have been implemented at higher frequencies than ever before by leveraging a th...
Reflectionless filters are a class of lumped‐element circuits and transmission‐line topologies which, insofar as the elements are ideal, have identically zero reflection coefficients at all ports and at all frequencies from DC to infinity. Developed in the mid 2010's, they differ from previous first‐ and second‐order constant‐resistance implementat...
Single-ended circuit topologies, and a theorem for the development thereof, are presented with which one may realize constant-resistance (or reflectionless) filters, having ideally zero reflection coefficient at all frequencies and from all ports, suitable for elliptic and pseudo-elliptic filter responses. The proposed theorem produces topologies o...
Single-ended circuit topologies, and a theorem for the development thereof, are presented with which one may realize constant-resistance (or reflectionless) filters, having ideally zero reflection coefficient at all frequencies and from all ports, suitable for elliptic and pseudo-elliptic filter responses. The proposed theorem produces topologies o...
A TEM line to double-ridged waveguide launcher and horn antenna are disclosed. The launcher uses multiple probes or one or more wide-aspect probes across the ridge gap to minimize spreading inductance and a TEM combiner or matching taper to match the impedance of the probes over a broad bandwidth. The horn uses a power-law scaling of gap height rel...
A teaching assistant once told me that, as microwave engineers, impedance matching is "what we do." We do much more than that, of course. But I think it is true that this is what most of our more complex tasks ultimately boil down to. To design an amplifier, you have to match the impedance of the transistor. To design an antenna, you have to match...
The next-generation Very Large Array (ngVLA) is an astronomical observatory planned to operate at centimeter wavelengths (25 to 0.26 centimeters, corresponding to a frequency range extending from 1.2 to 116 GHz). The observatory will be a synthesis radio telescope constituted of approximately 244 reflector antennas each of 18 meters diameter, and 1...
Modifications of the authors' previously published, generalized, lumped-element, reflectionless filter topologies are presented, which remove the original constraints on the relative values of its prototype parameters. Thus, any transfer function which can be realized as the transmission or reflection coefficient of a conventional ladder prototype...
Modifications of the authors' previously-published, generalized, lumped-element, reflectionless filter topologies are presented which remove the original constraints on the relative values of its prototype parameters. Thus, any transfer function which can be realized as the transmission or reflection coefficient of a conventional ladder prototype m...
The next-generation Very Large Array (ngVLA) is an astronomical observatory planned to operate at centimeter wavelengths (25 to 0.26 centimeters, corresponding to a frequency range extending from 1.2 GHz to 116 GHz). The observatory will be a synthesis radio telescope constituted of approximately 214 reflector antennas each of 18 meters diameter, o...
Reflectionless transmission line filters, as well as a method for designing such filters is disclosed. These filters preferably function by absorbing the stop-band portion of the spectrum rather than reflecting it back to the source, which has significant advantages in many different applications. The insertion of additional transmission line sect...
A new 1.4 GHz 19-element, dual-polarization, cryogenic phased array feed (PAF) radio astronomy receiver has been developed for the Robert C. Byrd Green Bank Telescope (GBT) as part of FLAG (Focal L-band Array for the GBT) project. Commissioning observations of calibrator radio sources show that this receiver has the lowest reported beamformed syste...
A new 1.4 GHz 19-element, dual-polarization, cryogenic phased array feed (PAF) radio astronomy receiver has been developed for the Robert C. Byrd Green Bank Telescope (GBT) as part of FLAG (Focal L-band Array for the GBT) project. Commissioning observations of calibrator radio sources show that this receiver has the lowest reported beamformed syste...
Reflectionless filters provide a novel approach to filter design and offer several practical advantages over conventional microstrip designs for ultra-wideband (UWB) applications. In addition to delivering superior electrical performance, they are smaller, lower cost and more repeatable making them suitable candidates for use in commercial applicat...
In this paper, we describe the development of a new L-band (1.4 GHz) Cryogenic Phased Array Feed (PAF) system, referred to as the GBT2 array. Results from initial measurements made with the GBT2 array are also presented. The PAF was developed for the Green Bank Telescope (GBT) as part of the Focal L-band Array for the GBT (FLAG) project. During the...
Reflectionless low-pass, high-pass, band-pass, band-stop, all-pass, and all-stop filters, as well as a method for designing such filters is disclosed, along with a method of enhancing the performance of such filters through the use of sub-networks to further modify and improve the frequency response. These filters preferably function by absorbing t...
The growing number of phased array feeds (PAFs) being built for radio astronomy demonstrates an increasing need for low noise amplifiers (LNAs) that are designed for repeatability, low noise, and ease of manufacture. The focal L-band array for the Green Bank Telescope (FLAG) is a cooperative effort by Brigham Young University (BYU) and the National...
The growing number of phased array feeds (PAF) being built for radio astronomy demonstrates an increasing need for low noise amplifiers (LNA) that are designed for repeatability, low noise, and ease of manufacture. Specific design features which help to achieve these goals include the use of unpackaged transistors (for cryogenic operation), single-...
We report on the development and characterization of a compact, full-waveguide bandwidth (WR-10) signal source for general-purpose testing of mm-wave components. The MMIC-based multichip module is designed for compactness and ease-of-use, especially in size-constrained test sets such as a wafer probe station. It takes as input a cm-wave CW referenc...
We report on the development and characterization of a compact, full-waveguide bandwidth (WR-10) signal source for general-purpose testing of mm-wave components. The MMIC-based multichip module is designed for compactness and ease-of-use, especially in size-constrained test sets such as a wafer probe station. It takes as input a cm-wave CW referenc...
The design, fabrication, and measurement of a coax to double-ridged waveguide launcher and horn antenna is presented. The novel launcher design employs two symmetric field probes across the ridge gap to minimize spreading inductance in the transition, and achieves better than 15 dB return loss over a 10:1 bandwidth. The aperture-matched horn uses a...
A low-noise cryogenic phased array feed (PAF) is in development for the Green Bank Telescope (GBT). The feed consists of electrically small elements tuned to operate near 1.4 GHz and optimized for active impedance matching to cooled front end low noise amplifiers (LNAs). A prototype cryogenic PAF with analog fiber link, down-converters and streamin...
This paper expands on the previously described reflectionless filters - that
is, filters having, in principle, identically-zero reflection coefficient at
all frequencies - by introducing a wide variety of new reflectionless
structures that were not part of the original publication. In addition to
extending the lumped-element derivation to include t...
The design, fabrication, and measurement of a coax to double-ridged waveguide
launcher and horn antenna is presented. The novel launcher design employs two
symmetric field probes across the ridge gap to minimize spreading inductance in
the transition, and achieves better than 15 dB return loss over a 10:1
bandwidth. The aperture-matched horn uses a...
A cryogenic phased array feed operating at L-band is in development for the Green Bank Telescope (GBT). The feed consists of electrically small feed elements optimized for active impedance matching to cooled front end low noise amplifiers (LNAs), down-converters, a real-time streaming data acquisition system, and beamforming algorithms applied in p...
This paper presents the design and characterization of W-band IQ sub-harmonic MMIC mixers based on the UMS BES Schottky diode process. The mixers were characterized at 300 K and 20 K physical temperature. They are a key component for the compact heterodyne multi-chip modules to be used in the 16-element Argus focal plane array, which will be deploy...
A method is described for enhancing the performance of previously described
reflectionless filters - that is, filters having, in principle,
identically-zero reflection coefficient at all frequencies - by coupling the
left- and right-side stop-band terminations via a two-port sub-network.
Specific examples for the choice of sub-network are given whi...
Methods, systems, and devices using an algorithm that consists of scoring the bits in the data stream with a periodicity of N, where N is the word-length in bits, and then selecting as the most significant bit the one which receives the highest score after some large number of samples are disclosed. The condition under which bit bk receives a point...
Reflectionless low-pass, high-pass, band-pass, and band-stop filters, as well as a method for designing such filters is disclosed. The filters function by absorbing the stop-band portion of the spectrum rather than reflecting it back to the source, which has significant advantages in many applications.
Reflectionless low-pass, high-pass, band-pass, and band-stop filters, as well as a method for designing such filters is disclosed. The filters function by absorbing the stop-band portion of the spectrum rather than reflecting it back to the source, which has significant advantages in many different applications.
Cryogenic cooling of receivers to reduce their noise temperature is especially important in radio astronomy, as the antenna noise temperature is determined by the cosmic microwave background radiation (2.725 K) modified by the presence of atmosphere. For frequencies up to 120 GHz direct amplification at cryogenic temperatures is typically employed...
The reflectionless filter cell described in this article alleviates many
system problems associated with excess out-of-band gain, impedance mismatches,
and component interactions. The simplest filter cell exhibits a third-order
Inverse Chebyshev response with 14.47 dB peak stopband attenuation, and several
can be cascaded for additional attenuation...
A design methodology and equations are described for lumped-element filter prototypes having low-pass, high-pass, bandpass, or bandstop characteristics with theoretically perfect input- and output-match at all frequencies. Such filters are a useful building block in a wide variety of systems in which the highly reactive out-of-band termination pres...
The scattering parameters of generalized compact orthomode transducers using
azimuthally-distributed field probes in a dual-mode waveguide are analyzed.
Theoretical expressions constraining the mutual coupling between the probes are
derived and evaluated for three- and four-probe orthomode transducers with and
without a coaxial reference port for c...
A design methodology and synthesis equations are described for lumped-element filter prototypes having low-pass, high-pass, band-pass, or band-stop characteristics with theoretically perfect input- and output-match at all frequencies. Such filters are a useful building block in a wide variety of systems in which the highly reactive out-of-band term...
This article reports on the first step in a focused program to re-optimize
radio astronomy receiver architecture to better take advantage of the latest
advancements in commercial digital technology. Specifically, an L-Band
sideband-separating downconverter has been built using a combination of careful
(but ultimately very simple) analog design and...
This white paper offers cautionary observations about the planning and development of new, large radio astronomy instruments. Complexity is a strong cost driver so every effort should be made to assign differing science requirements to different instruments and probably different sites. The appeal of shared resources is generally not realized in pr...
Radio astronomy observations in the coming decade will require new levels of sensitivity while mapping large regions of space with much greater efficiency than is achieved with current telescopes. This requires new instrumentation with the greatest achievable sensitivity, dynamic range, and field of view. Receiver noise is quickly approaching funda...
We present the design of several wideband, millimeter-wave, MMIC, medium power amplifiers using a newly developed high-power, high-yield, 70 nm gate-length GaAs MMIC pHEMT process. These amplifiers cover a range of about 65-125 GHz, and were designed for the purpose of driving sub-millimeter wave multipliers in the local oscillator subsystem of the...
A W-band MMIC low-noise amplifier (LNA) was designed and fabricated using NGST's 35 nm InP HEMT process. It was packaged in a WR-12 module and tested at 297K and 17.5K ambient temperatures. At room temperature, the WR-12 LNA module has 26-30 dB gain from 70 to 92 GHz and less than 300K noise temperature from 65-86 GHz. At 17.5K ambient temperature,...
The 100m diameter Robert C. Byrd Green Bank Telescope (GBT) is the worlds most sensitive instrument for detection of interstellar molecular lines in the frequency range 10 to 50 GHz. With the GBT, scientists have recently discovered several new interstellar molecules and have started large molecular line surveys. To increase sensitivity to complex...
Progress in many areas of astronomy requires large-area surveys and observations of
extended objects. This includes the cosmic microwave background, nearby galaxies, the
Milky Way, and regions of star-forming regions within our galaxy. The ability to carry
out such studies is critically dependent on the development of affordable high-sensitivity
fo...
This paper presents the design and current status of a K-Band Focal Plane Array (KFPA) for the Green Bank Telescope (GBT). The prototype array will go online with 7 independent dual-polarized beams, but the design target is a fully-populated instrument with approximately 60 beams on the sky. This project presents a number of technical challenges, i...
As part of an initiative to reduce the size, weight, and complexity of radio astronomy receivers and to place the conversion from analog to digital signals as close to the telescope feed as possible, a prototype single-conversion, sideband-separating mixer receiver with a tunable local oscillator (LO) between 5 and 9 GHz has been built and tested....
In this paper we present several topologies of simple non-reflective filters using transmission lines and resistive elements. These filters are well-matched at all frequencies, making them especially suitable for gain slope equalizers without the need for external attenuators or isolators. The application of these filters to a 2-4 GHz, plusmn15 dB...
This paper describes the design methodology used to develop local oscillators for the ultra-sensitive single-ended sub-millimeter wave mixers used in ALMA. Recent results of the ALMA LO system are presented, showing little or no noise added to the receiver. Measurements of excess amplitude noise from ALMA LO prototypes in the development phase are...
A 0.1-mum InP HEMT Ka-band LNA with high and flat gain, very low noise figure and low VSWR has been developed. Across the entire Ka-band, of 26 GHz to 40 GHz, the MMIC LNA demonstrated associated gain of 21.9 plusmn 0.9 dB and an average noise figure of 1.5 dB with a minimum of 1.3 dB at 34 GHz. The LNA chip was cryogenically cooled to 12 K where i...
We report on the local oscillator (LO) development for the ALMA 64-antenna sub-millimeter wave telescope array. Measurements of output power and AM noise are presented for four wideband electronically-tuned MMIC-based LOs up to 710 GHz.
This paper describes a set of power amplifier (PA) modules containing InP high electron mobility transistor (HEMT) monolithic millimeter-wave integrated circuit (MMIC) chips. The chips were designed and optimized for local oscillator sources in the 90-130 GHz band for the Atacama large millimeter array telescope. The modules feature 20-45 mW of out...
A set of MMIC frequency multipliers and balanced mixers have been designed for the local oscillator system of the Atacama large millimeter array (ALMA). These millimeter-wave elements form a critical link in the active multiplier chains between the relatively low frequency microwave oscillators and the very high frequency submillimeter-wave, cooled...
The techniques for integrating two types of high performance waveguide filters within the body of a MMIC-based multi-function module (MFM) are demonstrated. The module shown is a dual-channel Ka-band down converter for the Deep Space Network (DSN) array. The loss of the probe transitions at either end are considered in order to evaluate the perform...
The concept proposed by the United States for the Swaure Kilometer Array consists of a large number of small diameter paraboloidal dishes. Among the many advantages of this so-called Lage-N/Small-D (LNSD) array over other proposed designs is the ability to reach higher frequencies. However, a key element to the success of any large-N architecture i...
One of the most exciting applications of millimeter-wave engineering and compound semiconductor technology is instrumentation for radio astronomy. It is a field rich with unique technical challenges and innovative solutions. This paper presents an overview of some of the circuits and systems that have been developed for the Atacama Large Millimeter...
W-band direct detection circuits have been designed and fabricated for use in a passive millimeter wave camera. The circuits are based on the recently developed Sb-heterostructure diode. We measure record voltage responsivities in test circuits, up to 8,000 mV/mW from 75 to 93 GHz, with input power from -50 to -30 dBm. Performance was similar in an...
We present a proposed project plan for implementing a water vapour radiometer phase correction scheme for the EVLA. The plan comprises four phases: (i) the design and production of a prototype Compact Water Vapour Radiometer (CWVR) for testing the K-band RFI environment of EVLA antennas; (ii) an investigation of how to apply WVR corrections to astr...
We have developed amplifier based receivers using Indium Phosphide high electron mobility transistor (HEMT) monolithic microwave integrated circuit (MMIC) technology. These compact receivers are designed with atmospheric temperature and humidity sounding requirements in mind, operating at 100-125 GHz around the 118 GHz oxygen line, and at 160-185GH...
This paper summarizes the design and measured performance of a MMIC power amplifier for W-band. The chip was fabricated on a 50 μm GaAs substrate using 0.1 μm AlGaAs/InGaAs/GaAs pseudomorphic-HEMT technology. Measurements show that it has small-signal gain of 19±1 dB from 72 to 95 GHz. During scalar measurements with moderate heat-sinking, the chip...
It is a well-known problem with microstrip backward-wave couplers that directivity suffers due to the differing phase velocities of the even- and odd-mode waves. A fully-planar alternative is the forward-wave, or codirectional-coupler, but these structures have not yet been widely accepted, in part because they are complex and tedious to design. He...
As device technology improves, interest in the millimeter-wave band grows. Wireless communication systems migrate to higher frequencies, millimeter-wave radars and passive sensors find new solid-state implementations that promise improved performance, and entirely new applications in the millimeter-wave band become feasible. The circuit or system d...
A W-band GCPW (grounded coplanar waveguide) MMIC diode tripler using GaAs PHEMT process is developed. An anti-parallel diode pair is used to produce third harmonic signal and a GCPW band pass filter is used to reject the spurious signal. The measured conversion loss is 18-20 dB from 87 to 102 GHz at 14-dBm input power. It is observed that if the fi...
High Electron Mobility Transistors (HEMTs) play a crucial role in receivers for millimeter and sub-millimeter astrophysical observations. Low noise HEMTs are used extensively in low noise receiver front ends, for coherent direct detection and intermediate frequency (IF) amplification in heterodyne detection. Power amplifiers are becoming widely use...
A novel transition from coaxial cable to microstrip is presented
in which the coax connector is perpendicular to the substrate of the
printed circuit. Such a right-angle transition has practical advantages
over more common end-launch geometries in some situations. The design is
compact, easy to fabricate, and provides repeatable performance of
bett...
This paper describes the design, construction, and testing of a
compact W-Band signal source module. The MMIC-based module is an active
×6 frequency multiplier, requiring a 12.5 to 18.5 GHz, 2 mW input
signal, which can be provided by any microwave synthesizer or other
readily available oscillators. The design Includes directional couplers
with int...
We have developed a new zero bias millimeter wave diode based on quantum tunneling in an InAs/AlSb/GaSb nanostructure. It is ideal for square law radiometry and passive millimeter wave imaging. Excellent sensitivity has been demonstrated at present up to 110 GHz, with higher bandwidth predicted for smaller area diodes.
High-resolution passive millimeter wave imaging cameras require per pixel detector circuitry that is simple, has high sensitivity, low noise, and low power. Detector diodes that do not require bias or local oscillator input, and have high cutoff frequencies are strongly preferred. In addition, they must be manufacturable in large quantities with re...
High-resolution passive millimeter wave imaging cameras require per pixel detector circuitry that is simple, has high sensitivity, low noise, and low power. Detector diodes that do not require bias or local oscillator input, and have high cutoff frequencies are strongly preferred. In addition, they must be manufacturable in large quantities with re...
In this paper, a MMIC frequency doubler based on an InP HEMT and grounded CPW (GCPW) technology is reported. The doubler demonstrated a conversion loss of only 2 dB and output power of 5 dBm at 164 GHz. The 3 dB output power bandwidth is 14 GHz, or 8.5%. This is the best reported result for a MMIC HEMT doubler above 100 GHz.
We have developed a new zero bias millimeter wave diode based on
quantum tunneling in an InAs/AlSb/GaSb nanostructure. It is ideal for
square law radiometry and passive millimeter wave imaging. Excellent
sensitivity has been demonstrated at present up to 110 GHz, with higher
bandwidth predicted for smaller area diodes
We report the design and evaluation of a broadband, balanced mixer
for 100-140 GHz using a HEMT MMIC process on a 75 μm InP substrate.
The circuit uses Schottky diodes as mixing elements. It demonstrates a
conversion loss of 15 ± 2 dB from 100-130 GHz with 5 dBm LO drive
at 80 GHz, Measurements indicate a wide IF bandwidth extending beyond 50
GHz....
Design and test data for a full waveguide band MMIC tripler using
anti-parallel Schottky diodes are reported in this paper. The circuit
outputs between -3.7 dBm and +2.0 dBm from 75 to 110 GHz. When tuned for
power flatness, the output is between -4.6 dBm and -1.3 dBm across the
band. The conversion efficiency is about 1.5% in both cases. To the
au...
Questions
Question (1)
I have a proof-of-concept prototype in mind that requires a lossless negative floating inductor. I have researched and found many active circuits that can synthesize them, using conventional op-amps, current-feedback op-amps, OTAs, current conveyors, and many, (MANY) more. Most of these devices are unfamiliar to me. I am willing to learn about them, but am hoping for some helping narrowing down the field. Can people who have experience with these devices suggest what they think are the best approaches and why? I am particular interested in aspects like:
1. Ease of stabilization
2. Commercial availability (for a circuit board prototype)
3. Frequency range
Incidentally, I will need a negative grounded capacitor as well, but the floating inductor seemed trickier, so I thought I would start with that.
Thanks in advance for your help...
