C. Nishimoto

5-100 GHz InP CPW MMIC 7-section distributed amplifier

The development of a single-stage 5-100-GHz InP monolithic microwave IC (MMIC) amplifier with an average gain of more than 5.0 dB is reported. This MMIC distributed amplifier has the highest frequency and bandwidth of operation (5-100 GHz) reported for wideband amplifiers. The active devices in this seven-section distributed amplifier are 0.1- mu m mushroom-gate InGaAs-InAlAs lattice-matched HEMTs on a semiinsulating InP substrate. Coplanar waveguide is the transmission medium for this 100-GHz MMIC with an overall chip dimension of 500 by 860 mu m. This is the first 100-GHz coplanar waveguide circuit on an InP substrate.<<ETX>>

High-gain, low-noise monolithic HEMT distributed amplifiers up to 60 GHz

Ultrabroad-bandwidth distributed amplifiers with cutoff frequencies of 45 to 60 GHz were developed using 0.25- mu m high-electron-mobility transistors (HEMTs) with a mushroom gate profile. Both single and cascode HEMTs were used as the active devices in the amplifiers. A measured gain as high as 10+or-1 dB from 5 to 50 GHz and a gain of 8+or-1 dB from 5 to 60 GHz, respectively, were achieved from amplifiers using cascode HEMTs. The measured noise figure for these amplifiers is approximately 3-4 dB in the Ka-band. The chip size is 2.3*0.9 mm. Device considerations, circuit design, monolithic IC fabrication, and the measured performance of the amplifiers are outlined.<<ETX>>

A 2-20 GHz, High-Gain, Monolithic HEMT Distributed Amplifier

A low-noise 2-20 GHz monolithic distributed amplifier utilizing 0.3-micron gate-length HEMT devices has achieved 11-dB +- 0.5 dB of gain. This represents the highest gain reported for a distributed amplifier using single FET gain cells. A record low noise figure of 3 dB was achieved mid-band (7-12 GHz). The circuit design utilizes five HEMT transistors of varying width with gates fabricated by E-beam lithography.

A monolithic 40-GHz HEMT low-noise amplifier

A description is given of a monolithic, reactively matched 40-GHz low-noise amplifier using a 0.25- mu m high-electron-mobility transistor (HEMT) as the active device. Standard processing techniques were used for most of the fabrication steps. An amplifier using a triangular gate profile achieved approximately 6.5-dB gain and a 5-dB noise figure from 38 to 44 GHz. The gain of the amplifier increased to 8 dB and the noise figure decreased to 4 dB when the gate was replaced by one with a mushroom-like profile. The chip size is 1.1 mm*1.1 mm.<<ETX>>A monolithic, single-stage HEMT (high-electron-mobility transistor) low-noise amplifier has been developed at 40 GHz. This amplifier includes a single 0.25- mu m gate-length HEMT active device with on-chip matching and biasing circuits. A gain of 6.5 dB and a noise figure of 5 dB were measured from 38 to 44 GHz. By replacing the triangular gate profile with a mushroom gate profile the amplifier achieved 8-db gain and 4-dB noise figure from 36 to 42 GHz. The chip size is 1.1 mm*1.1 mm.<<ETX>>

A monolithic Ka-band HEMT low-noise amplifier

A monolithic, single-stage high-electron-mobility transistor (HEMT) low-noise amplifier was developed for the 20-40-GHz band. This amplifier includes a single 0.25- mu m-gate-length HEMT active device with on-chip matching and biasing circuits. A gain of approximately 6 dB from 20 to 38 GHz and a noise figure of approximately 5 dB from 26.5 to 38 GHz were measured. The chip size is 2.2 mm*1.1 mm.<<ETX>>

Field emission carbon thin film and its lifetime and stability

Tests were performed on FEPET, Inc. carbon thin film cathodes to characterize lifetime, resistance to environmental conditions, and performance stability. The cathodes were found to exhibit half lifetimes on the order of 7000 h in sealed glass envelopes. Operation in oxygen and water were found to degrade the cathode performance severely. Xenon had no effect on the cathode lifetime or stability, demonstrating its resistance to ion sputtering. During characterization in vacuum systems, initial turn on was quick and stable. Carbon thin films are suitable cathode materials for display, microelectronic, and ion propulsion uses.

NOTFET: a high-frequency InP nonlinear transistor

A device called the nonlinearly optimized transconductance field-effect transistor (NOTFET) has been developed for nonlinear circuit applications. An InP NOTFET with two g/sub m/ peaks based on InGaAs and InAlAs channels was designed fabricated, and tested for harmonic generation up to 12 GHz, demonstrating the device concept and its advantages compared to conventional FETs and HEMTs. Multipeak g/sub m//V/sub GS/ characteristics also can be obtained by using a multiheterojunction material structure with uncoupled quantum wells, a possibility which is under investigation.<<ETX>>

Sensitivity of a 40 GHz HEMT low-noise amplifier to material and processing variations

The design of a monolithic, single-stage low-noise amplifier at 40 GHz for application to satellite communication is presented. The amplifier includes a single 0.25- mu m-gate-length HEMT active device with on-chip matching and biasing circuits. A gain of 8 dB and a noise figure of 4 dB were measured from 36 to 42 GHz for an amplifier with a mushroom gate profile. Using a triangular-gate-profile device with a lower gate-to-drain feedback capacitance, the amplifier achieves a 10 dB peak gain at 43 GHz. The chip size is 1.1*1.1 mm/sup 2/. >