High gain operational amplifier implemented in 0.5 μm GaAs E/DHEMT technology

A high voltage gain operational amplifier implemented in 0.5 μm GaAs E/D HEMT technology is presented. The amplifier principally consists of a differential input stage and a high gain cascode stage which was developed by Toumazou and Haigh (1990). On-wafer measurement verifies that the amplifier achieves an open-loop voltage gain of 73 dB and a unity-gain bandwidth of 1.78 GHz     

Direct ion-implanted 0.12 μm GaAs MESFET with ft of121 GHz and fmax of 160 GHz

An 0.12 μm gate length direct ion-implanted GaAs MESFET exhibiting excellent DC and microwave characteristics has been developed. By using a shallow implant schedule to form a highly-doped channel and an AsH₃ overpressure annealing system to optimize the shallow dopant profile, the GaAs MESFET performance was further improved. Peak transconductance of 500 mS/mm was obtained at I_ds =380 mA/mm. A noise figure of 0.9 dB with associated gain of 8.9 dB were achieved at 18 GHz. The current gain cutoff frequency f_max of 160 GHz indicates the suitability of this 0.12 μm T-gate device for millimeter-wave IC applications     

AlGaN/GaN HEMTs on silicon substrates with fT of 32/20GHz and fmax of 27/22 GHz for 0.5/0.7 μm gate length

AlGaN/GaN HEMTs on silicon substrates have been realised and their static and small signal characteristics investigated. The AlGaN/GaN (x=0.23) material structures were grown on (111) p-Si by LP-MOVPE. Devices exhibit a saturation current density of 0.53 to 0.68 A/mm and a peak extrinsic transconductance of 110 mS/mm. A unity gain frequency of 20 and 32 GHz and a maximum frequency of oscillation of 22 and 27 GHz are obtained for devices with a gate length of 0.7 and 0.5 μm, respectively. These values are the highest reported so far on AlGaN/GaN/Si HEMTs and are comparable to those known for devices using sapphire and SiC substrates     

High gain wideband amplifier IC using 0.7 μm GaAs MESFETtechnology

A high gain wideband differential amplifier with a new circuit configuration is proposed and monolithically integrated by using 0.7 μm-gate GaAs MESFET IC technology. The fabricated IC exhibited gain of 16.7 dB and bandwidth of 3.2 GHz. A gain twice that of a conventional differential GaAs-MESFET amplifier was achieved with small bandwidth degradation     

0-1 GHz waveguide 10.6 μm GaAs electrooptic modulator

A GaAs electrooptic modulator for use in 10.6-μm laser frequency shifting applications is described. High-beam-quality output signals with a frequency tunability of 0.1-1.0 GHz were demonstrated. Thick epitaxial GaAs-AlGaAs waveguide structures were successfully fabricated into single-mode channel waveguides with excellent optical and electrooptic properties. A lumped-element modulator, with electrical and electrooptic characteristics in good agreement with theory, was operated at RF drive power levels up to the reverse breakdown voltage limit. The insertion loss of the modulator was quite high, due to absorption losses in the epitaxial material     

7.8 GHz small-signal modulation bandwidth of 1.3 μm DQWGaInAsN/GaAs laser diodes

High frequency characterisation of double quantum well GaInAsN laser diodes emitting at 1.28 μm is reported. The 3 dB bandwidth of ridge waveguide lasers was measured to be 7.8 GHz at 120 mA under CW operation demonstrating the potential for high speed operation of these devices     

High-speed 8:1 multiplexer and 1:8 demultiplexer implemented withAlGaAs/GaAs HBTs

An 8:1 multiplexer (MUX) and 1:8 demultiplexer (DMUX) implemented with AlGaAs/GaAs heterojunction bipolar transistors are described. The circuits were designed for lightwave communications, and were demonstrated to operate at data rates above 6 Gb/s. These are among the fastest 8-b MUX-DMUX circuits ever reported. Each contains about 600 transistors and consumes about 1.5 W. The pair provides features such as resettable timing, data framing, and clock recovery circuitry, and a built-in decision circuit on the DMUX. Emitter-coupled logic (ECL) compatible input/output (1/O) signals are available. The circuits were implemented with bi-level current mode logic (CML) and require a -5.2-V power supply and a +1-V bias for ECL compatibility     

20 W CW surface emitting 0.8 μm GaAs/GaAlAs laser diodes

A continuous-wave optical power density of 200 W/cm² is reported for the first time for a 0.1 cm² element of a surface emitting GaAs/GaAlAs wafer. The laser facets are cleaved on-wafer by a microcleavage technique. The output optical beam is reflected by 45°-integrated beam deflectors situated at a distance of 15 μm from each laser facet. The lasers were soldered junction-up on a microchannel CuW cooler. The drive current at 20 W CW is 40 A with a slope efficiency of 0.7 W/A     

Low power data decision IC for 20-40 Gbit/s data links using 0.2μm AlGaAs/GaAs HEMTs

A decision IC for optical data links at bit rates of 20-40 Gbit/s has been realised by using 0.2 μm AlGaAs/GaAs HEMT technology and tested on-wafer at bit rates up to 25 Gbit/s. The IC can be operated with a supply from ~3.3 to 5.2 V and a DC current of ~50 mA     

4H-SiC MESFET's with 42 GHz fmax

We report for the first time the development of state-of-the-art SiC MESFETs on high-resistivity 4H-SiC substrates. 0.5 μm gate MESFETs in this material show a new record high f_max of 42 GHz and RF gain of 5.1 dB at 20 GHz. These devices also show simultaneously high drain current, and gate-drain breakdown voltage of 500 mA/mm, and 100 V, respectively showing their potential for RF power applications     

0.10 μm graded InGaAs channel InP HEMT with 305 GHzfT and 340 GHz fmax

We report here 305 GHz f_T, 340 GHz f_max, and 1550 mS/mm extrinsic g_m from a 0.10 μm In_xGa _1-xAs/In_0.62Al_0.48As/InP HEMT with x graded from 0.60 to 0.80. This device has the highest f_T yet reported for a 0.10 μm gate length and the highest combination of f _T and f_max reported for any three-terminal device. This performance is achieved by using a graded-channel design which simultaneously increases the effective indium composition of the channel while optimizing channel thickness     

Guided-wave 1.3/1.55 μm wavelength division multiplexer based onmultimode interference

To improve the wavelength sensitivity of the multimode interference phenomenon and thus reduce the device length, a restricted-resonance multimode interference scheme and a lower beat length ratio were adopted to design a novel 1.3/1.55 μm wavelength division multiplexer. Using the modal propagation analysis, transmission characteristics of the device were investigated     

An experimental determination of electron drift velocity in0.5-μm gate-length ion-implanted GaAs MESFET's

A microwave technique was used to determine the electron drift velocity in an ion-implanted GaAs MESFET with a 0.5×100-μm gate. The characteristics of the velocity versus drain-to-source voltage for a GaAs MESFET exhibit a peak velocity of 4.0, 3.3, and 2.2×10 ⁷ cm/s at 100%, 65%, and 31% of I_dss, respectively. This work presents the first experimental determination of electron drift velocity at various gate biases and provides verification for velocity overshoot in ion-implanted GaAs MESFETs     

A 20 GHz Band 0.5 W GaAs FET Amplifier for Satellite Communications

GaAs FET amplifier modules for 20 GHz band satellite communications have been developed using newly developed power FETs. The deep recess gate structure was adopted in the power FET, which improved both power output capability and power gain. Power added efficiency of 22 percent with more than 1 W power output has been achieved with 3 mm gate width FETs. The amplifier modules containing two-stage internally matched FET's can be hermetically sealed in metal packages. The modules had 8.4-8.9 dB linear gain in the 17.7-18.8 GHz band and 7.9-8.4 dB linear gain in the 18.5-19.6 GHz band. The power output at 1 dB gain compression point was more than 0.5 W. The third-order intermodulation distortion ratio was 81-83 dB at 18.2 GHz and 77-80 dB at 18.9 GHz, when individual output signal power was -4 dBm.     

GaInAsN/GaAs laser diodes operating at 1.52 μm

GaInAsN/GaAs double quantum well (DQW) lasers have been grown by solid source molecular beam epitaxy (MBE). Room-temperature pulsed operation is demonstrated for a ridge waveguide laser diode at a wavelength of 1517 nm. This is the first report of room-temperature laser emission in the 1.5 μm range based on GaAs     

Continuous-wave operation of 1.30μm GaAsSb/GaAs VCSELs

1.30 μm VCSELs using GaAsSb quantum wells, which operate continuous-wave at and above room temperature (RT), are reported. A threshold current as low as 1.2 mA at RT and a maximum CW operating temperature of 70°C are demonstrated     

0.1 μm Schottky-collector AlAs/GaAs resonant tunneling diodes

The Schottky-collector resonant tunneling diode (RTD) is an RTD with the normal N+ collector and ohmic contact replaced by a Schottky contact, thereby eliminating the associated parasitic resistance. With submicron Schottky contact dimensions, the remaining components of the parasitic series resistance can be greatly reduced, resulting in an increased maximum frequency of oscillation, f_max. AlAs/GaAs Schottky-collector RTDs were fabricated using 0.1 μm T-gate technology developed for high electron mobility transistors. From their measured dc and microwave parameters, and including the effect of the quantum well lifetime, f_max=900 GHz is computed     

Bistable operation of 0.8 μm GaInAsP/GaAs lasers

Quaternary GaInAsP prepared on GaAs is a very promising material for optoelectronic devices in alternating AlGaAs/GaAs systems. The authors report bistable operation in stripe geometry GaInAsP/GaAs DH lasers with gain region and absorbing region in the laser resonator. A hysteresis loop is observed in the I/L curve under pulsed operation at room temperature     

Germanium-diffused waveguides in silicon for λ=1.3 μm andλ=1.55 μm with losses below 0.5 dB/cm

The authors present a simple technique for the fabrication of integrated optical channel waveguides that are prepared by indiffusion of an E-beam evaporated amorphous alloy of germanium and silicon into commercially available silicon with low dopant concentration, using only simple technological processes such as standard lithography, PVD, and diffusion. The waveguides are polarization independent and have waveguide losses as low as 0.3 dB/cm at wavelengths of λ=1.3 μm and λ=1.55 μm. The spot sizes are well suited for low-loss single-mode fiber device coupling, being on the order of a few microns in both horizontal and vertical directions     

1.3 μm InGaAs/GaAs strained quantum well lasers with InGaPcladding layer

Using MOVPE, we fabricated strained quantum well 1.3 μm lasers with an InGaP cladding layer on a GaAs substrate. The lasers had a high gain coefficient of 60 cm^-1. Lasers with high reflection facets had a low threshold current density of 500 A/cm², and a high characteristic temperature of 100 K