K.W. Kobayashi

A 108-GHz InP-HBT monolithic push-push VCO with low phase noise and wide tuning bandwidth

This paper reports on what is believed to be the highest frequency bipolar voltage-controlled oscillator (VCO) monolithic microwave integrated circuit (MMIC) so far reported. The W-band VCO is based on a push-push oscillator topology, which employs InP HBT technology with peak f/sub T/s and f/sub max/s of 75 and 200 GHz, respectively. The W-band VCO produces a maximum oscillating frequency of 108 GHz and delivers an output power of +0.92 dBm into 50 /spl Omega/. The VCO also obtains a tuning bandwidth of 2.73 GHz or 2.6% using a monolithic varactor. A phase noise of -88 dBc/Hz and -109 dBc/Hz is achieved at 1- and 10-MHz offsets, respectively, and is believed to be the lowest phase noise reported for a monolithic W-band VCO. The push-push VCO design approach demonstrated in this work enables higher VCO frequency operation, lower noise performance, and smaller size, which is attractive for millimeter-wave frequency source applications.

A 6-GHz integrated phase-locked loop using AlGaAs/GaAs heterojunction bipolar transistors

A fully integrated 6-GHz phase-locked-loop (PLL) fabricated using AlGaAs/GaAs heterojunction bipolar transistors (HBTs) is described. The PLL is intended for use in multigigabit-per-second clock recovery circuits for fiber-optic communication systems. The PLL circuit consists of a frequency quadrupling ring voltage-controlled oscillator (VCO), a balanced phase detector, and a lag-lead loop filter. The closed-loop bandwidth is approximately 150 MHz. The tracking range was measured to be greater than 750 MHz at zero steady-state phase error. The nonaided acquisition range is approximately 300 MHz. This circuit is the first monolithic HBT PLL and is the fastest yet reported using a digital output VCO. The minimum emitter area was 3 mu m*10 mu m with f/sub t/=22 GHz and f/sub max/=30 GHz for a bias current of 2 mA. The speed of the PLL can be doubled by using 1- mu m*10- mu m emitters in next-generation circuits. The chip occupies a die area of 2-mm*3-mm and dissipates 800 mW with a supply voltage of -8 V. >

A novel HBT distributed amplifier design topology based on attenuation compensation techniques

We report on a novel HBT distributed amplifier design which achieves the highest gain-bandwidth product (GBP) per device f/sub T/ so far reported for HBT distributed amplifiers. This paper introduces a new design topology for HBT DAs which incorporates attenuation compensation on both the input and output transmission lines. A four-section HBT DA using this novel topology achieves a gain of 15 dB and a 3-dB bandwidth of >15 GHz. The resulting gain-bandwidth product is 84 GHz. When normalized to the device f/sub T/, this DA achieves the highest normalized gain-bandwidth-product figure of merit for HBT DAs, /spl ap/3.67, which is a 55% improvement over existing state-of-the-art performance. Attenuation compensation of the input transmission line is realized using HBT active impedance transformations. The resulting transistor configuration consists of a common-collector driving a common-emitter-cascode transistor pair. This configuration offers 15-20 dB more available gain for the device unit cell, and results in gain-bandwidth product improvements of 200% over a conventional common-emitter DA configuration. This paper discusses the design theory, techniques, and measurements of this newly developed HBT distributed amplifier topology. >

Ultra-low dc power GaAs HBT S- and C-band low noise amplifiers for portable wireless applications

We report on a 2.1 mW low dc power GaAs HBT LNA with 2.0 dB noise figure and 8.9 dB gain at 2 GHz. This amplifier achieves a Gain/NF.P/sub dc/ ratio figure of merit of 2.10 (1/mW) which is the highest reported at S-band. Under low dc power bias of 2 V and 0.46 mA (0.92 mW), the amplifier achieves 5.2 dB gain, 3.01 dB noise figure and a Gain/P/sub dc/ figure of merit of 5.65 (dB/mW) which is also the highest reported in this frequency band. In addition, a 2-stage self-biased C-band LNA which achieves a minimum noise figure of 2.4 dB at 5 GHz, 16.2 dB gain, with only 72 mW of dc power was also demonstrated. This is believed to be the lowest noise figure performance so far reported for an HBT amplifier above 3 GHz. Both HBT LNAs are fabricated using a relaxed 3 /spl mu/m emitter width low cost GaAs production foundry process. The high performance obtained from HBTs at very low dc bias makes them attractive for portable wireless applications in the Industrial-Scientific-Medical (ISM) frequency bands.

Monolithic HEMT-HBT integration by selective MBE

We have achieved successful monolithic integration of high electron mobility transistors and heterojunction bipolar transistors in the same microwave circuit. We have used selective molecular beam epitaxy and a novel merged processing technology to fabricate monolithic microwave integrated circuits that incorporate both 0.2 /spl mu/m gate-length pseudomorphic InGaAs-GaAs HEMTs and 2 /spl mu/m emitter-width GaAs-AlGaAs HBTs. The HEMT and HBT devices produced by selective MBE and fabricated using our merged HEMT-HBT process exhibited performance equivalent to devices fabricated using normal MBE and our baseline single-technology processes. The selective MBE process yielded 0.2 /spl mu/m HEMT devices with g/sub m/=600 mS/mm and f/sub T/=70 GHz, while 2/spl times/10 /spl mu/m/sup 2/ HBT devices achieved /spl beta/>50 and f/sub T/=21.4 GHz at J/sub c/=2/spl times/10/sup 4/ A/cm/sup 2/. The performance of both a 5-10 GHz HEMT LNA with active on-chip HBT regulation and a 20 GHz Darlington HBT amplifier are shown to be equivalent whether fabricated using normal or selective MBE. >

A 50-MHz-55-GHz multidecade InP-based HBT distributed amplifier

The authors report on a 50-MHz-55-GHz multidecade bandwidth InP-based heterojunction bipolar transistor (HBT) MMIC distributed amplifier (DA) which achieves the widest bandwidth and highest frequency of operation so far demonstrated for a bipolar amplifier. The HBT MMIC DA was fabricated using a high-speed 1-μm InAlAs-InGaAs-InP HBT base-undercut technology with peak fTs and fmaxs of 80 and 200 GHz, respectively, in order to obtain broad-band gain. Key to this work is the successful employment of HBT active load terminations used on both the input and output DA transmission lines in order to extend the low-frequency gain performance down to baseband. With only 82 mW of DC power consumption, the amplifier obtains measured gains of 7.6 dB at 50 MHz, 5.7 dB at 30 GHz, 5.8 dB at 50 GHz, and 3.1 dB at 55 GHz. Simulations of a monolithically integrated InGaAs p-i-n photodetector predicts a baseband 47-GHz photoreceiver response with an effective transimpedance of 38-dB/spl Omega/. The baseband millimeter-wave capability of the InP-based HBT DA and its compatibility with InGaAs photodetectors makes this technology attractive for future generation (>40 Gb/s) high-data-rate light-wave applications.

Monolithic GaAs HBT p-i-n diode variable gain amplifiers, attenuators, and switches

The authors report on monolithic circuits integrating HBTs and p-i-n diode using a common HBT MBE structure. An HBT variable gain amplifier using p-i-n diode as a variable resistor achieved a gain of 14.6 dB, a bandwidth out to 9 GHz, a gain control range of >15 dB, and an IP3 of 28 dBm. A two-stage HBT p-i-n diode attenuator from 1-10 GHz and an X-band one-pole two-throw HBT p-i-n diode switch were also demonstrated. The two-stage p-i-n attenuator has over 50 dB dynamic range at 2 GHz and a maximum IP3 of 9 dBm. The minimum insertion loss is 1.7 dB per stage and has a flat response to 10 GHz. The X-band switch has an insertion loss of 0.82 dB and an off-isolation of 25 dB. The bandwidth is greater than 35% and the IP3 is greater than 34.5 dBm. These circuits consist of p-i-n diodes constructed from the base-collector MBE layers of a baseline HBT process. This is the first monolithic integration of p-i-n diode switch, variable gain control, and attenuation functions in an HBT technology without additional processing steps or MBE material growth. >

GaAs HBT wideband matrix distributed and Darlington feedback amplifiers to 24 GHz

The designs and performances of a 2-24 GHz distributed matrix amplifier and 1-20 GHz 2-stage Darlington coupled amplifier based on an advanced HBT MBE profile that increases the bandwidth response of the distributed and Darlington amplifiers by providing lower base-emitter and collector-base capacitances are presented. The matrix amplifier has a 9.5 dB nominal gain and a 3-dB bandwidth to 24 GHz. This result benchmarks the highest bandwidth reported for an HBT distributed amplifier. The input and output VSWRs are less than 1.5:1 and 2.0:1, respectively. The total power consumed is less than 60 mW. The chip size measures 2.5*2.6 mm/sup 2/. The 2-stage Darlington amplifier has 7 dB gain and 3-dB bandwidth beyond 20 GHz. The input and output VSWRs are less than 1.5:1 and 2.3:1, respectively. This amplifier consumes 380 mW of power and has a chip size of 1.66*1.05 mm/sup 2/. >

A 2 Watt, Sub-dB Noise Figure GaN MMIC LNA-PA Amplifier with Multi-octave Bandwidth from 0.2-8 GHz

This paper reports on a 0.2-8 GHz high dynamic range GaN MMIC LNA-PA which achieves sub-dB noise figure and a PldB of 2 watts. The GaN MMIC utilizes a 0.2 mum AlGaN/GaN-SiC HEMT technology with an fT ~75 GHz. At high power bias (15 V/400 mA), the MMIC amplifier achieves sub-dB NF ~0.7-0.9 dB over a 2-8 GHz band. At low bias(12 V, 200 mA), the amplifier achieves ~0.5dB over the same band. This is believe to be the lowest NF reported for a multi-octave MMIC amplifier in the S-and C-band frequency range. In addition, the amplifier obtains ultra high linearity with an OIP3 of 43.2-46.5 dBm and P1 dB of 32.8-33.2 dBm (2 watts) over a 2-6 GHz bandwidth. The PAE at P1 dB is ~28.6-31%. The Psat is 34.2 dBm with 39% PAE @ 2 GHz. To our knowledge, this is the first report of a multi-octave MMIC amplifier with sub-dB NF and a pout >2 Watt.

GaAs HBT 0.75-5 GHz multifunctional microwave-analog variable gain amplifier

We report on a GaAs HBT 3-stage variable gain amplifier operating over a 0.75-5 GHz frequency band. The amplifier is broken up into a single-ended HBT LNA pre-amplifier, an analog current steering differential cascode cell for variable gain control, and a differential amplifier output stage. The broadband pre-amplifier is required to reduce the inherently noisy differential cascode stage, and an output differential amplifier is used to provide output drive capability and differential to single-ended conversion. The VGA has a maximum gain of 23.8 dB gain, an IP3>18 dBm, and a noise figure of 6.5 dB. The variable gain control range is >35 dB. This chip demonstrates the versatility of HBT IC technology which can integrate digital, analog, and microwave circuit functions to achieve high performance in a single monolithic chip. >