Tangential Signal Sensitivity Research Articles

Microwave Photonic Crystal Video Receiver for Radar Interception

This article introduces an approach of a crystal video receiver (CVR) based on microwave photonics (MWP) to detect pulsed radar signals. The pulsed radiofrequency (RF) envelope detection is achieved using the optical self-homodyne technique on the photodetection process. The proposed architecture uses a phase modulator (PM) to modulate the optical carrier and a fiber Bragg grating (FBG) to filter the spectrum to convert phase to intensity modulation. The self-homodyne technique eliminates the optical carrier at photodetector to reduce the shot noise and saturation on it. Moreover, the photodetection is performed at the radar pulse baseband, allowing to obtain transimpedance gain. The theoretical principle and an experimental demonstration are presented. A CVR sensitivity of 53 V/mW and a tangential signal sensitivity (TSS) equal to −40 dBm is achieved for a pulsed radar operating at 17 GHz.

DESIGN AND IMPLEMENTATION OF A HIGH DYNAMIC RANGE C BAND DOWN-CONVERTER

A technique that expands dynamic range (DR) of frequency down-converters in the C band frequency is presented. Primary characteristics of down-converter are evaluated to conflrm that it can be used in microwave receivers. The C band down-converter is carried out by the combination of RF mixers, band pass interdigital fllter, and X band combline fllter which are designed entirely for this project. Attainment of the perfect receiver is the flnal purpose of this paper, and a method that causes 72dB dynamic range, high tangential signal sensitivity and flne gain ∞atness is used for achieving the mentioned purpose. These efiorts improve the dynamic range about 19dB and gain ∞atness about 3.07dB.

3–5 GHz UWB Impulse Radio Transmitter and Receiver MMIC Optimized for Long Range Precision Wireless Sensor Networks

Abstract-In this paper, an ultra wideband impulse radio (UWB-IR) transmitter and receiver monolithic microwave integrate circuit (MMIC) for precision localization sensor network is presented. Longer range is achieved with low power consumption at the transmitter by fully exploiting FCC's peak power constraint efficiently. The transmitter and receiver MMIC are fabricated on a commercial low cost 2 μm GaAs HBT process. The transmitter MMIC peak power output is 20 dBm with power consumption of 0.8 mW at 1 MHz pulse repetitive rate. The receiver MMIC uses non-coherent detection and has a 44 dB front-end conversion gain. The receiver MMIC is cascaded with a 500 MHz baseband amplifier to achieve input tangential signal sensitivity (TSS) of - 71 dBm. Equivalent time sampling using analogue to digital converters running at around a few MHz is utilized for precise time of arrival ranging with low cost components. Two dimensional wireless localization network utilizing time difference of arrival (TDOA) is constructed and test results covering an 80 X 90 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> area show position error variance of less than 10 cm. Ranging at 200 m is demonstrated with range error variance of better than 15 cm.

Optimization and Realization of Planar Isolated GaAs Zero-Biased Planar Doped Barrier Diodes for Microwave/Millimeter-Wave Power Detectors/Sensors

A high tangential signal sensitivity (TSS) zero-bias GaAs planar doped barrier (PDB) diode for microwave and millimeter-wave power detection applications is presented. The fabricated PDB diodes have shown 4 dB better TSS at 35 GHz than that of reported devices, considerably increasing the minimum detectable power and widening the dynamic range. The high TSS was obtained by optimizing the PDB layer structures, namely, the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$delta$</tex> -doped <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$hboxp^++$</tex> layer and the two intrinsic layers, and by employing ion bombardment to better define the device and reduce parasitic effects. The isolation properties of ion bombarded epitaxial layers on GaAs substrates were examined and optimized to have a sheet resistivity of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$hbox10^8~Omega/hboxsq$</tex> . The temperature dependence of the barrier height of the PDB diode has been investigated experimentally, showing positive temperature coefficient and, hence, better thermal stability. We have also defined the critical barrier height and derived its analytical expression, which gives the theoretically lowest possible barrier height of a PDB diode.

High tangential signal sensitivity GaAs planar doped barrier diodes for microwave/millimeter-wave power detector applications

Tangential signal sensitivity (TSS) of GaAs planar doped barrier (PDB) detector diodes as low as -55 dBm at 35 GHz has been achieved. In comparison with that of reported devices, this value is 6-dBm better, implying the diodes can detect much lower power hence widening the dynamic range of microwave/millimeter-wave power detectors.

Characterization of resonant tunneling diodes for microwave and millimeter-wave detection

The authors report on the direct detection capabilities of resonant tunneling diodes in the 10-100 GHz range. An open circuit voltage sensitivity of 1750 mV/mW (in Ka-band) was measured. This is higher than the sensitivity of comparatively based commercially available solid-state detectors. The detector properties are a strong function of diode bias and the measured tangential signal sensitivity (-32 dBm at Ka-band with 1-MHz bandwidth) and the dynamic range (25 dB) of the diode are smaller compared to other solid-state detectors. >

Millimeter‐wave detection using resonant tunnelling diodes

AbstractA lattice‐matched InGaAs/InAlAs resonant tunnelling diode is studied as a video detector in the millimeter‐wave range. Tangential signal sensitivity and video resistance measurements are made as a function of bias and frequency. A tangential signal sensitivity of — 37 dBm (1 MHz amplifier bandwidth) with a corresponding video resistance of 350 Ω at 40 GHz has been measured. These results, to the best of our knowledge, are the first millimeter‐wave tangential signal sensitivity and video resistance results for a resonant tunnelling diode.

Silicon-based millimeter-wave integrated circuits

Abstract Microwaves at frequencies above 30 GHz (millimeter waves), which offer several advantages, are mainly used at present for military applications. A broad civil market will be opened if a cost-effective planar integration can be achieved. The suitability of high resistivity silicon for planar millimeter-wave integration is described. To produce silicon monolithic millimeter-wave integrated circuits (SIMMWICs) the device structures are grown by molecular beam epitaxy on high-resistivity silicon substrate. Discrete impact avalanche transit time (IMPATT) and Schottky diodes fabricated from this material show excellent performances at 100 GHz: they have more than 1 W oscillator output power and a detector tangential signal sensitivity of − 52 dB m at around 90 GHz. For specific applications the device characteristics can be influenced by the introduction of SiGe heterojunctions. The MITATT (mixed tunneling avalanche transit time) oscillator and the resonant tunneling detector are given as examples. Hybrid integrated transmitters, voltage-controlled oscillators, and mixers can be fabricated on high resistivity silicon. The transmitter oscillator with a double-drift IMPATT diode as the active element emits a maximum continuous wave output power of 200 mW at 73 GHz. The advantages of the coplanar waveguide are pointed out and monolithic integrated oscillators and detectors are demonstrated. The chip with a coplanar Schottky diode as the detector element and a microstrip antenna with 36 radiating elements shows a sensitivity of 65 microV microW −1 cm −2 . The first applications of the described circuits for traffic surveillance are described and discussed.

Millimeter-wave planar InP Schottky diodes and their small-signal equivalent circuit

Two planar indium phosphide Schottky diode designs have been fabricated and analyzed for millimeter-wave detector applications up to 150 GHz. Device structure and fabrication are discussed, and small-signal equivalent circuit models are presented. The following topics are included: the planar InP diode structure fabricated by megaelectron volt ion implantation. DC and RF measurements, circuit model values, and 94-GHz small-signal detector performance. The zero-bias detector sensitivity at 94 GHz was measured to be as high as 400 mV/mW, and the calculated tangential signal sensitivity was -56 dBm. >

High-performance GaAs heterojunction bipolar transistor monolithic logarithmic IF amplifiers

Logarithmic IF amplifiers that implement both true and successive-detection designs are reported. Monolithically cascaded log gain stages are used to achieve piecewise-approximated logarithmic functions for the compression of signals over a wide dynamic range. The heterojunction bipolar transistor (HBT) IC fabrication process is based on a 3- mu m-emitter, self-aligned-base ohmic metal transistor using both molecular-beam epitaxy (MBE) and metal-organic metal vapor deposition (MOCVD) growth structures. The true log amp integrates four dual-gain (limiting and unity gain) stages without on-chip video detection. Its performance includes DC-3-GHz IF/video bandwidth, 400-ps rise time, <+or-dB log error over approximately=40-dB dynamic range at 3 GHz, and a tangential signal sensitivity (noise) of -60 dBm (test-set limited). The successive-detection log amp, designed for lower frequency and dynamic range applications, uses three limiting gain stages and four detector stages to achieve a 550-MHz bandwidth and <-0.34-dB log error over a 27-dB dynamic range. It is able to process 13-ns pulses with 5.0-ns and 5.2-ns risetimes and fall times, respectively.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The Stabilization of Mixer Diode Performance Against L.O. Power Changes with Optimum DC Bias

The advantages of using a particular dc forward bias in maintaining receiver sensitivity for fairly large reductions in local oscillator power are experimentally verified. Definite improvement of performance is obtained over broad band operation where L.O. power level may vary considerably. For each of the mixer diodes investigated there is a particular optimum bias for each diode type where both the input signal level and local oscillator RF impedances as well as the IF impedance are practically stationary with respect to very large changes in local oscillator power level. At optimum bias, signal frequency RF and IF impedances were found to vary by only about ten per cent for L.O. power reduced from 1 mw to 1 /spl mu/w. This results in considerably less reduction in tangential signal sensitivity over that obtained in the unbiased or overbiased condition.