High-Frequency Si-MOSFET's

Silicon (Si-) MOSFET's with 0.8-mu m channel, made by conventional technology and optimized for microwave applications, have noise figures of 3.7 dB at 4 GHz and maximum frequencies of oscillation of 10 to 12 GHz. The noise and radio-frequency (RF) small signal performance are only slightly affected by double ion implantation of the channel region, used to shift the threshold voltage from - 2 V to +0.2 V. Excess noise is generated in the implanted MOSFET's for lower V/sub DS/ values than in unimplanted ones. The variation of the noise parameters with drain current is lower in implanted devices. The RF equivalent circuit analysis indicates negligible parasitic lead resistances, but high feedback capacitance. A comparison with GaAs MESFET's of the buried channel type showed the Si-MOSFET's to have lower third-order harmonic distortion when driven by a 1-GHz signal source.     

A SOI-RF-CMOS technology on high resistivity SIMOX substrates formicrowave applications to 5 GHz

A silicon-on-insulator (SOI) RF complementary metal-oxide-semiconductor (CMOS) technology for microwave applications up to 5 GHz has been developed. The technology is based on ultra large scale integration (ULSI) CMOS processing using a high resistivity separation through implanted oxygen (SIMOX) substrate of typically 10 kΩcm. Dedicated RF n-channel and RF p-channel MOSFET's with an effective channel length of 0.20 and 0.40 μm have been fabricated using a multiple gate finger design. Maximum frequencies of operation f _max of 46 GHz (NMOS) and 16 GHz (PMOS) have been measured. Metal-Insulator-Metal (MIM) capacitances with up to 63 pF with 70 nF/cm ², planar inductances with up to 25 nH and a quality factor up to 12 and coplanar waveguides with a loss <2.8 dB/cm at 5 GHz are monolithically integrated in the technology without additional processes and materials. Using this SOI-CMOS technology we have fabricated integrated silicon RF circuits, e.g., amplifiers, oscillators, and mixers, operating in the 2 GHz range     

A deep-submicrometer microwave/digital CMOS/SOS technology

0.35-μm complementary metal-oxide-semiconductor (CMOS)/silicon-on-sapphire (SOS) n- and p-channel MOSFETs with a metal-over-polysilicon T-gate structure for monolithic microwave integrated circuit (MMIC) and digital applications are reported. The measured values for the current-gain cutoff frequency f_T were ⩾20 GHz for both n-channel and p-channel devices, and the values for the unilateral power-gain cutoff frequency f_max were 37 GHz for the p-channel and 53 GHz for the n-channel MOSFETs. The low effective resistance of the T-gate structure contributed to the very high f_max values. It is believed that these are the highest f_T and f_max values ever reported for MOS devices. The potential of SOS submicrometer MOSFETs for microwave circuit applications is demonstrated     

High-performance millimeter-wave ion-implanted GaAs MESFETs

GaAs MESFETs (metal-epitaxial-semiconductor-field-effect transistors) with ion-implanted active channels have been fabricated on 3-in-diameter GaAs substrates which demonstrate device performance comparable with that of AlGaAs/InGaAs pseudomorphic HEMT (high-electron-mobility transistor) devices. Implanted MESFETs with 0.5-μm gate lengths exhibit an extrinsic transconductance of 350 mS/mm. From S-parameter measurements, a current-gain cutoff frequency f₁ of 48 GHz and a maximum-available-gain cutoff frequency f_max greater than 100 GHz are achieved. These results clearly demonstrate the suitability of ion-implanted MESFET technology for millimeter-wave discrete device, high-density digital, and monolithic microwave and millimeter-wave IC applications     

GaAs heterojunction bipolar transistor device and IC technology forhigh-performance analog and microwave applications

GaAs-AlGaAs n-p-n heterojunction bipolar transistor (GaAs HBT) technology and its application to analog and microwave functions for high-performance military and commercial systems are discussed. In many applications the GaAs HBT offers key advantages over the alternative advanced silicon bipolar and III-V compound field-effect-transistor (FET) approaches. TRW's GaAs HBT device and IC fabrication process, basic HBT DC and RF performance, examples of applications, and technology qualification work are presented and serve as a basis for addressing general capability issues. A related 3-μm emitter-up, self-aligned HBT IC process provides excellent DC and RF performance, with simultaneous gain-bandwidth product, f_T, and maximum frequency of oscillation, f_max, of approximately 20-40 GHz and DC current gain β≈50-100 at useful collector current densities ≈3-10 kA/cm², early voltage ≈500-1000 V, and MSI-LSI integration levels. These capabilities facilitate versatile DC-20-GHz analog/microwave as well as 3-6 Gb/s digital applications, 2-3 G sample/s A/D conversion, and single-chip multifunctions with producibility     

In0.52Al0.48As/InxGa1-xAs (0.53⩽x⩽0.70) lattice-matched and strainedheterostructure insulated-gate FETs

The DC and microwave properties of In_0.52Al_0.48 Al/In_xGa_1-xAs (0.53⩽x⩽0.70) heterostructure insulated gate field-effect transistors (HIGFETs) with a quantum well channel design are presented. DC and microwave transconductances (g_m) are enhanced as the In content is increased in the InGaAs channel. An intrinsic microwave g _m value of 428 mS/mm and a K-factor of 1140 mS/mm-V have been obtained for 1.0-μm gate length with the 65% In channel devices. The sheet charge density, drift mobility, transconductance, current-gain cutoff frequency (f_T), and maximum oscillation frequency (f _max) all show a continuous improvement up to 65% In content ( f_T=22.5 GHz with 53% and f_T=27 GHz with 65% In; the corresponding f_max change is from 6.5 to 8 GHz). The device performance degrades as the In content is increased to 70%. DC and microwave characteristics show the presence of negative differential resistance (NDR) up to 2.7 GHz     

A Si bipolar 21-GHz/320-mW static frequency divider

A silicon bipolar divide-by-eight static frequency divider was developed. A state-of-the-art advanced borosilicate-glass self-aligned (A-BSA) transistor technology that has a cutoff frequency of 40 GHz at V_ce=1 V was applied. Optimum circuit and layout designs were carried out for high-speed/low-power operation. The single-ended input realized by an on-chip metal-insulator-metal (MIM) capacitor makes it easy to use in microwave applications. Ultrahigh-speed operation, up to 21 GHz, was realized, with 320-mW power dissipation from a single +5-V supply. The static frequency divider is a suitable prescaler for phase-locked oscillators (PLOs), completely covering microwave frequencies from L band through Ku band (1-18 GHz)     

Super-low-noise performance of direct-ion-implanted 0.25-μm-gateGaAs MESFET's

The authors report on advanced ion implantation GaAs MESFET technology using a 0.25-μm `T' gate for super-low-noise microwave and millimeter-wave IC applications. The 0.25×200-μm-gate GaAs MESFETs achieved 0.56-dB noise figure with 13.1-dB associated gain at 50% I_DSS and 0.6 dB noise figure with 16.5-dB associated gain at 100% I_DSS at a measured frequency of 10 GHz. The measured noise figure is comparable to the best noise performance of AlGaAs/GaAs HEMTs and AlGaAs/InGaAs/GaAs pseudomorphic HEMTs     

Integration of high-Q GaAs varactor diodes and 0.25 μmGaAs MESFET's for multifunction millimeter-wave monolithic circuitapplications

Two technologies are demonstrated whereby high-Q, vertical-structure, abrupt-junction varactor diodes are monolithically integrated with 0.25-μm GaAs MESFETs on semi-insulating GaAs substrates for multifunction millimeter-wave monolithic circuit applications. Diodes with various anode sizes have been realized with measured capacitance swings of >2.1:1 from 0 V to -4 V and series resistances of approximately 1 Ω. Diodes having a zero bias capacitance of 0.35 pF have Q's of >19000 (50 MHz) with -4 V applied to the anode. Under power bias conditions, the MESFETs have a measured gain of >6 dB at 35 GHz with extrapolated values for f _t and f_max of 32 GHz and 78 GHz, respectively. Using these technologies, a monolithic Ka-band voltage controlled oscillator (VCO) containing a varactor diode, a 0.25-μm GaAs MESFET, and the usual MMIC passive components has been built and tested. At around 31 GHz, the circuit has demonstrated 60-mW power output with 300 MHz of tuning bandwidth     

High-speed, low-noise InGaP/GaAs heterojunction bipolar transistors

We have demonstrated self-aligned InGaP/GaAs heterojunction bipolar transistors (HBT's) with excellent dc, microwave, and noise performance. A 3×10 μm² emitter finger device achieved a cutoff frequency of f_T=66 GHz and a maximum frequency of oscillation of f_max=109 GHz. A minimum noise figure of 1.12 dB and an associated gain of 11 dB were measured at 4 GHz. These results are the highest combined f_T+f_max and the lowest noise figure reported for an InGaP/GaAs HBT and are attributed to material quality and the use of self-aligned base contacts. These data clearly demonstrate the viability of InGaP/GaAs HBT's for high-speed, low-noise circuit applications     

High-frequency performances of a partially depleted 0.18-μmSOI/CMOS technology at low supply voltage-influence of parasiticelements

This paper shows for the first time the high-performances of a partially depleted 0.18-μ_m technology at low supply voltage. The SOI technology uses a standard digital process with a TiSi ₂ salicided polysilicon gate and a low dose SIMOX substrate. The process does not include any specific feature like T-gate, or high-resistivity SOI substrate. At 1 V, and 2 GHz the current gain and the unilateral power gain are higher than 15 dB for both 0.18 μm gate length NMOS and PMOS transistors. At 1.5 V, the 0.18-μm NMOS and PMOS show a transition frequency of, respectively, 51 GHz and 23 GHz and a maximum oscillation frequency of 28 GHz and 13 GHz. These results have been obtained with an optimized transistor geometry to reduce the influence of the access resistances. The high-frequency potential of this 0.18-μm SOI technology demonstrates the possible integration of microwave functions with digital circuits on a single chip for low-power, low-voltage applications like wireless telecommunication     

Equivalent Circuit of the Schottky-Barrier Field-Effect Transistor at Microwave Frequencies (Short Papers)

Johnson's high-frequency representation theory for MOSFET's, experimentally confirmed by Hopkins up to 1 GHz, is extended in this short paper for SBFET's and is found to substantially agree with data for 1-mu m- and 1/2-mu m-gate GaAs SBFET's up to 12 GHz. Regenerative-feedback conductance not accounted for by conventional models is seen to be present in SBFET's at microwave frequencies.     

High-temperature superconducting delay lines and filters onsapphire and thinned LaAlO3 substrates

The very low microwave surface resistance of high-temperature-superconductor (HTS) thin films allows the realization of microwave devices with performance superior to those made by conventional technology. Superconducting delay lines, for example, have very low propagation loss and dispersion. Long, low-loss, superconducting delay lines on both thinned LaAlO₃ and sapphire substrates are presented. Delay lines with 27- and 44-ns delay have been made, for the first time, on 5-cm-diameter 254- and 127-μm-thick LaAlO₃ substrates, respectively. The insertion losses at 77 K and 6 GHz are 6 and 16 dB, respectively. Delay lines with 9-ns delay have, for the first time, been produced on M-plane sapphire substrates and demonstrate, at 77 K, an insertion loss of 1.0 dB at 6 GHz. A 2.5%-bandwidth 10 GHz four pole edge-coupled bandpass filter on M-plane sapphire substrates is also reported. The filter has minimum insertion loss of less than 0.5 dB at 9.75 GHz and 71 K     

Metamorphic InP/InGaAs heterojunction bipolar transistors on GaAssubstrate: DC and microwave performances

High-performance InP/In_0.53Ga_0.47As metamorphic heterojunction bipolar transistors (MHBTs) on GaAs substrate have been fabricated using In_xGa_1-xP strain relief buffer layer grown by solid-source molecular beam epitaxy (SSMBE). The MHBTs exhibited a dc current gain over 100, a unity current gain cutoff frequency (f_T) of 48 GHz and a maximum oscillation frequency (f_MAX) of 42 GHz with low junction leakage current and high breakdown voltages. It has also been shown that the MHBTs have achieved a minimum noise figure of 2 dB at 2 GHz (devices with 5×5 μm ² emitter) and a maximum output power of 18 dBm at 2.5 GHz (devices with 5×20 μm² emitter), which are comparable to the values reported on the lattice-matched HBTs (LHBTs). The dc and microwave characteristics show the great potential of the InP/InGaAs MHBTs on GaAs substrate for high-frequency and high-speed applications     

Ultrahigh fT and fmax new self-alignmentInP/InGaAs HBT's with a highly Be-doped base layer grown by ALE/MOCVD

We report on a new self-alignment (SA) process and microwave performance of ALE/MOCVD grown InP/InGaAs heterojunction bipolar transistors (HBT's) with a base doping concentration of 1×10² 0 cm^-3. We obtained f_T of 161 GHz and f_max of 167 GHz with a 2×10 μm emitter. These high values indicate the best performance of InP/InGaAs HBT's ever reported, in so far as we know. These values were attained by reducing the base resistance using ALE/MOCVD and base-collector capacitance using a new SA process. These results indicate the great potential of these devices for ultrahigh-speed application     

Microwave pnp AlGaAs/GaAs heterojunction bipolartransistor

The microwave performance of a pnp AlGaAs/GaAs heterojunction bipolar transistor was demonstrated for the first time. Common emitter current gains of 60 were obtained using MOCVD grown structures with 100 nm thick base layers and self-aligned emitter-base contacts. f_t and f_max values were 12 and 20 GHz respectively. Under common-base configuration, 8 dB gain was obtained at 10 GHz. Device performance was characterised under CW and pulsed conditions     

Ultra-high-speed InP/InGaAs heterojunction bipolar transistors

We report on the microwave performance of InP/In_0.53Ga _0.47As heterojunction bipolar transistors (HBT's) utilizing a carbon-doped base grown by chemical beam epitaxy (CBE). The f_T and f_max of the HBT having two 1.5×10 μm² emitter fingers were 175 GHz and 70 GHz, respectively, at I_C=40 mA and V_CE=1.5 V. To our knowledge, the f _T of this device is the highest of any type of bipolar transistors yet reported. These results indicate the great potential of carbon-doped base InP/InGaAs HBT's for high-speed applications     

High-temperature microwave characteristics of GaAs MESFET deviceswith AlAs buffer layers

AlAs buffers used to reduce the leakage current of high-temperature GaAs MESFET devices are shown to have no detrimental effect on the microwave performance measured to 200°C. The f_t values decrease with increasing temperature, but do not appear to be influenced by the AlAs buffer. The f_max values also decrease with increasing temperature; however, they are improved with increasing AlAs buffer thickness due to a concomitant decrease in the device output conductance, At 200°C ambient temperature, f_t and f_max values of 14.5 GHz and 36.7 GHz, respectively, were measured     

Bandwidth Potential of Cascode HBT-Based TWAs as a Function of Transistor ${ f} _{max} /{ f} _{ T}$ Ratio

The bandwidth potential of cascode HBT-based broadband amplifiers following the traveling-wave amplifier (TWA) concept is studied. An approximate expression for the gain of the circuit is derived, which is based on the transistor small-signal model and the artificial transmission-line parameters. In this way, a relation between the HBT cutoff frequencies f_T and f_max and the 3-dB cutoff frequency f_c of the amplifier is obtained. This is very useful for assessing the gain-bandwidth potential of a given HBT technology for cascode-based TWAs. Applying these results, we study the potential of two technologies with different f_max / f_T ratios, an InP technology with f_max / f_T of 120 GHz/190 GHz, and a GaAs technology with f_max / f_T of 170 GHz/36 GHz. The higher influence of /max (compared to f_t) on f_c is quantitatively demonstrated. TWAs in both technologies were realized and measured, and good agreement between measurement and theory is obtained.     

Relation between low-frequency noise and long-term reliability ofsingle AlGaAs/GaAs power HBTs

Self-aligned AlGaAs/GaAs single heterojunction bipolar transistors (HBTs) were fabricated using an advanced processing technology for microwave and millimeter-wave power applications. These devices were processed simultaneously, on different epilayers with similar layer structure design supplied from different vendors. They showed similar dc characteristics (current gain, β=30) and their microwave performance was also identical (f_T=60 GHz, f_max=100 GHz). The HBTs showed different noise and reliability characteristics depending on their epilayer origin. HBT's from the high-reliability wafer showed MTTF of 10⁹ h at junction temperature of 120°C. They also presented very small 1/f noise with corner frequencies in the range of a few hundred Hz. Devices were subjected to bias and temperature stress for testing their noise and reliability characteristics. Stressed and unstressed devices showed generation-recombination noise with activation energies between 120-210 meV. Stress was found to increase the generation-recombination noise intensity but not its activation energy. These HBTs did not show any surface-related noise indicating that processing did not significantly influence noise characteristics. It was found that the base noise spectral density at low frequency can be correlated to the device long term reliability