Highly Stable, Low Noise Millimeter-Wave IMPATT Oscillator (Technical Notes)

A highly stable and low noise IMPATT oscillator at 75 GHz is realized by using the parametric injection locking technique along with an AFC circuit in which a crystal oscillator is used as a reference. Noise level of this oscillator is lower by 25 dB compared with that of the free-running IMPATT oscillator, and the frequency stability is as good as 10/sup -8/ /spl deg/C.     

Highly Stable, Low Noise Millimeter-Wave IMPATT Oscillator (Technical Notes)l

A highly stable and low noise IMPATT oscillator at 75 GHz is realized by using the parametric injection locking technique along with an AFC circuit in which a crystal oscillator is used as a reference. Noise level of this oscillator is lower by 25 dB as compared with that of the free-running IMPATT oscillator and the frequency stability is as good as 10/sup -8/ / /spl deg/C.     

Reliability investigation of 0.07-/spl mu/m InGaAs-InAlAs-InP HEMT MMICs with pseudomorphic In/sub 0.75/Ga/sub 0.25/As channel

The authors have investigated the reliability performance of G-band (183 GHz) monolithic microwave integrated circuit (MMIC) amplifiers fabricated using 0.07-/spl mu/m T-gate InGaAs-InAlAs-InP HEMTs with pseudomorphic In/sub 0.75/Ga/sub 0.25/As channel on 3-in wafers. Life test was performed at two temperatures (T/sub 1/ = 200 /spl deg/C and T/sub 2/ = 215 /spl deg/C), and the amplifiers were stressed at V/sub ds/ of 1 V and I/sub ds/ of 250 mA/mm in a N/sub 2/ ambient. The activation energy is as high as 1.7 eV, achieving a projected median-time-to-failure (MTTF) /spl ap/ 2 /spl times/ 10/sup 6/ h at a junction temperature of 125 /spl deg/C. MTTF was determined by 2-temperature constant current stress using /spl Delta/G/sub mp/ = -20% as the failure criteria. The difference of reliability performance between 0.07-/spl mu/m InGaAs-InAlAs-InP HEMT MMICs with pseudomorphic In/sub 0.75/Ga/sub 0.25/As channel and 0.1-/spl mu/m InGaAs-InAlAs-InP HEMT MMICs with In/sub 0.6/Ga/sub 0.4/As channel is also discussed. The achieved high-reliability result demonstrates a robust 0.07-/spl mu/m pseudomorphic InGaAs-InAlAs-InP HEMT MMICs production technology for G-band applications.     

A Highly Stabilized K/sub a/-Band Gunn Oscillator (Correspondence)

The construction and experimental results of a highly stabilized K/sub a/-band Gunn oscillator are described. The frequency stability is 3x10/sup -5/ at 25 GHz over the temperature range from 0 to 50/spl deg/C. An output power of more than 20 mW has been obtained in the frequency range up to 30 GHz. The frequency-saturation effect is also described.     

Highly Stabilized Half-Watt IMPATT Oscillator

An X-band IMPATT oscillator having a stabilized output power of over 0.5 watt has been developed. The oscillator consists of a main cavity and a directly coupled reaction-type cavity for stabilization. The oscillator has a frequency stability of 2.6x10/sup -5/ over a temperature variation ranging from 0/spl deg/ to 50/spl deg/C and an rms noise deviation of 15 Hz/1-kHz bandwidth at 500 kHz from the carrier. Design considerations have been made concerning the admittance characteristics of the circuit and of the diode to determine preferable circuit conditions for stabilization. The output-power loss due to the stabilization is as small as 0.4 dB. The oscillator is capable of operation in a frequency range of 10.7 to 11.7 GHz.     

Uncooled high-temperature (130/spl deg/C) operation of InGaAs-GaAs multiple quantum-well lasers at 20 Gb/s

Short-haul fiber-optic communication systems require high-speed semiconductor lasers that can operate uncooled over a wide temperature range. In this letter, we describe high-speed short-cavity InGaAs-GaAs multiple-quantum-well lasers operating at 1.1-/spl mu/m wavelength. The Fabry-Perot lasers were fabricated in a triple-mesa geometry suitable for on-wafer probing. With 3/spl times/200 /spl mu/m/sup 2/ ridge-waveguide lasers, which showed the best compromise between high-temperature and high-speed performance, a 3-dB modulation bandwidth of 14.5 GHz at 130/spl deg/C was achieved. Uncooled 20-Gb/s operation of these lasers is presented over a wide-temperature range from 25/spl deg/C to 130/spl deg/C without automatic power control.     

High-speed Modulation of InGaAs: Sb-GaAs-GaAsP quantum-well vertical-cavity surface-emitting lasers with 1.27-/spl mu/m emission wavelength

1.27-/spl mu/m InGaAs: Sb-GaAs-GaAsP vertical-cavity surface-emitting lasers (VCSELs) were grown by metal-organic chemical vapor deposition and exhibited excellent performance and temperature stability. The threshold current changes from 1.8 to 1.1 mA and the slope efficiency falls less than /spl sim/35% as the temperature raised from room temperature to 70/spl deg/C. With a bias current of only 5 mA, the 3-dB modulation frequency response was measured to be 8.36 GHz, which is appropriate for 10-Gb/s operation. The maximal bandwidth is measured to be 10.7 GHz with modulation current efficiency factor (MCEF) of /spl sim/5.25 GHz/(mA)/sup 1/2/. These VCSELs also demonstrate high-speed modulation up to 10 Gb/s from 25/spl deg/C to 70/spl deg/C.     

A Highly Stabilized GaAs FET Oscillator Using a Dielectric Resonator Feedback Circuit in 9-14 GHz

A new type of highly stabilized GaAs FET oscillator using a dielectric resonator and a stabilization resistor in the feedback circuit has been developed. The oscillator fabricated with a microwave integrated circuit has a high external quality factor Q/sub ex/ for more than1000 with no hysteresis phenomena. The microwave characteristics of the GaAs FET oscillator has revealed 1) high efficiency of 20 percent with 70-mW output power at 11.85 GHz, 2) a wide tuning range more than1000 MHz, 3) a wide oscillation frequency from 9 to 14 GHz with same MIC pattern by using five dielectric resonators of different sizes, 4) a high-frequency stability as low as /spl plusmn/ 150kHz in the tempature range from -20 to + 60/spl deg/ C, and 5) low FM noise of 0.07 Hz/ /spl radic/Hz at off-carrier frequency of 100kHz.     

5-GHz 32-bit integer execution core in 130-nm dual-V/sub T/ CMOS

A 32-bit integer execution core containing a Han-Carlson arithmetic-logic unit (ALU), an 8-entry /spl times/ 2 ALU instruction scheduler loop and a 32-entry /spl times/ 32-bit register file is described. In a 130 nm six-metal, dual-V/sub T/ CMOS technology, the 2.3 mm/sup 2/ prototype contains 160 K transistors. Measurements demonstrate capability for 5-GHz single-cycle integer execution at 25/spl deg/C. The single-ended, leakage-tolerant dynamic scheme used in the ALU and scheduler enables up to 9-wide ORs with 23% critical path speed improvement and 40% active leakage power reduction when compared to a conventional Kogge-Stone implementation. On-chip body-bias circuits provide additional performance improvement or leakage tolerance. Stack node preconditioning improves ALU performance by 10%. At 5 GHz, ALU power is 95 mW at 0.95 V and the register file consumes 172 mW at 1.37 V. The ALU performance is scalable to 6.5 GHz at 1.1 V and to 10 GHz at 1.7 V, 25/spl deg/C.     

Design and fabrication of a p-i-n photodiode with high responsivity and large alignment tolerances for 40-gb/s applications

This letter demonstrates an evanescently coupled p-i-n photodiode combined with a multimode diluted waveguide using a simple all 2-in InP processing that includes on-wafer mirrors etching and antireflection coating. A high responsivity of 0.81 A/W at 1.55 /spl mu/m with less than 0.4-dB polarization dependence and a large -1-dB vertical alignment tolerance of 2.70 /spl mu/m were achieved simultaneously with a bandwidth of 47 GHz. Stable operation for over 1000 h was obtained under bias stress and temperature at 200/spl deg/C.     

360/spl deg/ Varactor Linear Phase Modulator

Theory is presented which 1) derives the circuit impedance requirements to match the nonlinearity of the varactor reactance-versus-voltage curve to the tangent /spl theta/ curve to obtain 180/spl deg/ linear phase modulation from one diode; 2) gives the value and position of a resistor to make insertion loss invariant with phase; and 3) derives the circuit requirements for combining two 180/spl deg/ diode phase moduIators in an admittance adding network to obtain 360/spl deg/ phase modulation. Experiments are disclosed rising series tuning at 1 GHz providing 360/spl deg/ phase modulation within /spl plusmn/ 3.0 percent of linearity, and using shunt tuning at 5 GHz providing 360/spl deg/ phase modulation within /spl plusmn/ 3.3 percent of linearity. A discussion is given of the application of the modulators to the serrodyne function.     

DC, RF, and microwave noise performances of AlGaN/GaN HEMTs on sapphire substrates

High-performance AlGaN/GaN high electron-mobility transistors with 0.18-/spl mu/m gate length have been fabricated on a sapphire substrate. The devices exhibited an extrinsic transconductance of 212 mS/mm, a unity current gain cutoff frequency (f/sub T/) of 101 GHz, and a maximum oscillation frequency (f/sub MAX/) of 140 GHz. At V/sub ds/=4 V and I/sub ds/=39.4 mA/mm, the devices exhibited a minimum noise figure (NF/sub min/) of 0.48 dB and an associated gain (Ga) of 11.16 dB at 12 GHz. Also, at a fixed drain bias of 4 V with the drain current swept, the lowest NFmin of 0.48 dB at 12 GHz was obtained at I/sub ds/=40 mA/mm, and a peak G/sub a/ of 11.71 dB at 12 GHz was obtained at I/sub ds/=60 mA/mm. With the drain current held at 40 mA/mm and drain bias swept, the NF/sub min/,, increased almost linearly with the increase of drain bias. Meanwhile, the Ga values decreased linearly with the increase of drain bias. At a fixed bias condition (V/sub ds/=4 V and I/sub ds/=40 mA/mm), the NF/sub min/ values at 12 GHz increased from 0.32 dB at -55/spl deg/C to 2.78 dB at 200/spl deg/C. To our knowledge, these data represent the highest f/sub T/ and f/sub MAX/, and the best microwave noise performance of any GaN-based FETs on sapphire substrates ever reported.     

High temperature dielectric stability of liquid crystal polymer at mm-wave frequencies

The temperature dependent dielectric stability and transmission line losses of liquid crystal polymer (LCP) are determined from 11-105 GHz. Across this frequency range, LCP's temperature coefficient of dielectric constant, /spl tau//sub /spl epsi/r/, has an average value of -42 ppm//spl deg/C. At 11GHz the /spl tau//sub /spl epsi/r/ is the best (-3 ppm//spl deg/C), but this value degrades slightly with increasing frequency. This /spl tau//sub /spl epsi/r/ average value compares well with the better commercially available microwave substrates. In addition, it includes information for mm-wave frequencies whereas standard values for /spl tau//sub /spl epsi/r/ are usually only given at 10 GHz or below. Transmission line losses on 3- and 5-mil LCP substrates increase by approximately 20% at 75/spl deg/C and 50% or more at 125/spl deg/C. These insertion loss increases can be used as a design guide for LCP circuits expected to be exposed to elevated operating temperatures.     

A symmetrical 6-GHz fully integrated cascode coupling CMOS LC quadrature VCO

A fully symmetrical integrated quadrature LC oscillator with a wide tuning range of 1.2GHz is presented. The quadrature voltage-controlled oscillator (QVCO) is implemented using a symmetrical coupling method which has been used to produce the large tuning range with a low control voltage and to achieve good phase noise performance in 0.18/spl mu/m complementary metal oxide semiconductor technology. The measured phase noise at 1MHz offset from the center frequency (5.5GHz) is -115 dBc/Hz. The QVCO draws 3.2mA from a 1.8V supply. The equivalent phase error between I and Q signal was at most 0.5/spl deg/.     

100/spl deg/C 10 Gbit/s directly modulated InGaAsP DFB lasers with Ru-doped semi-insulating buried heterostructure

A directly modulated 1.3 /spl mu/m InGaAsP DFB laser with a simple buried structure using Ru-doped semi-insulating InP is presented. The high relaxation oscillation frequency of 10 GHz was obtained at 95/spl deg/C. Clear eye openings under 10 Gbit/s direct modulation were achieved from 0 to 100/spl deg/C.     

A GaN differential oscillator with improved harmonic performance

The first AlGaN/GaN HEMT based differential oscillator is reported. The MMIC oscillates at a frequency of 4.16 GHz and provides 22.9 dBm of power from one side at a biasing of V/sub gs/-1 V and V/sub ds/20 V. The HEMTs each have a 0.7 /spl mu/m/spl times/200 /spl mu/m gate. The second harmonic is 45 dB below the carrier and the third harmonic is more than 70 dB below the carrier. To our knowledge, this is the best reported harmonic performance for a GaN oscillator. The oscillator efficiency is between 4% and 9.4% depending on bias. The measured phase noise is -86.3 dBc and -115.7 dBc at offsets of 100 kHz and 1 MHz respectively. The phase noise at a 1 MHz offset is similar to the noise performance of FET based differential oscillators in other technologies.     

W-band investigation of material parameters, SAR distribution, and thermal response in human tissue

This investigation is divided into three parts. First, the W-band dielectric properties of different biological tissues are determined. Then, the electromagnetic field in the human eye and skin is simulated for plane-wave exposure. An analytical method is used to investigate the specific absorption rate (SAR) inside a layered model of the human skin between 3-100 GHz. Furthermore, the SAR inside a detailed model of the human eye is investigated numerically by the finite-difference time-domain method for a frequency of 77 GHz. Maximum local SAR values of 27.2 W/kg in skin tissue and 45.1 W/kg in eye tissue are found for 77 GHz and an incident power density of 1 mW/cm/sup 2/. In the third part of the investigation, the temperature changes of superficial tissue caused by millimeter-wave irradiation are measured by a thermal infrared imaging system. The exposure setup is based on a horn antenna with a Gunn oscillator operating at 15.8-dBm output power. The measurements showed a maximum temperature increase of 0.7/spl deg/C for a power density of 10 mW/cm/sup 2/ and less than 0.1/spl deg/C for 1 mW/cm/sup 2/, both in human skin (in vivo), as well as in porcine eye (in vitro). The comparison of the temperature measurements with a thermal bio-heat-transfer simulation of a layered skin model showed a good agreement.     

Parallel plate waveguide antenna for point-to-multipoint communication at millimetre-wave frequencies

Simulation and measurement results for a parallel plate waveguide antenna designed for a point-to-multipoint communication system at millimetre-wave frequencies is presented. The antenna consists of a waveguide feed, an H-plane horn, an enclosed parabolic reflector, a rectangular waveguide containing irises, and corrugated baffles. Half power beamwidths between 4.9/spl deg/-6.0/spl deg/ in elevation and 58/spl deg/-79/spl deg/ in azimuth are achieved for a bandwidth of 13%. The gain varies between 19 and 20 dBi for the frequency range between 21 and 25 GHz. The manufactured antenna is very compact with a size of 200/spl times/147/spl times/50 mm.     

Efficient Modulation of InP-based 1.3-/spl mu/m VCSELs with AsSb-based DBRs

We demonstrate efficient error-free 3.125-Gb/s modulation of InP-based 1.3-/spl mu/m vertical-cavity surface-emitting lasers with AsSb-based distributed Bragg reflectors up to 60/spl deg/C. These devices demonstrated high differential efficiencies [>60% at room temperature (RT)], which resulted in a required bias current for modulation of only 5.9 mA. The measured extinction ratios were greater than 8 dB up to 60/spl deg/C with a peak-to-peak drive voltage of only 800 mV. The 3-dB-down RT small-signal bandwidth was 4.4 GHz at a bias of 5.9 mA.     

A 2 V 1.8 GHz fully integrated CMOS dual-loop frequency synthesizer

A 2 V 1.8 GHz fully integrated CMOS dual-loop frequency synthesizer is designed in a standard 0.5 /spl mu/m digital CMOS process for wireless communication. The voltage-controlled oscillator (VCO) required for the low-frequency loop is designed using a ring-type VCO and achieves a tuning range of 89% from 356 to 931 MHz and a phase noise of -109.2 dBc/Hz at 600 kHz offset from 856 MHz. With an active chip area of 2000/spl times/1000 /spl mu/m/sup 2/ and at a 2 V supply voltage, the whole synthesizer achieves a tuning range from 1.8492 to 1.8698 GHz in 200 kHz steps with a measured phase noise of -112 dBc/Hz at 600 kHz offset from 1.86 GHz. The measured settling time is 128 /spl mu/s and the total power consumption is 95 mW.