David Pukala

InP HBT IC Technology for Terahertz Frequencies: Fundamental Oscillators Up to 0.57 THz

We report on the development of a 0.25-μm InP HBT IC technology for lower end of the THz frequency band (0.3-3 THz). Transistors demonstrate an extrapolated fmax of >;800 GHz while maintaining a common-emitter breakdown voltage (BVCEO) >;4 V. The transistors have been integrated in a full IC process that includes three-levels of interconnects, and backside processing. The technology has been utilized for key circuit building blocks (amplifiers, oscillators, frequency dividers, PLL, etc), all operating at ≥300 GHz. Next, we report a series of fundamental oscillators operating up to 0.57 THz fabricated in a 0.25-μm InP HBT technology. Oscillator designs are based on a differential series-tuned topology followed by a common-base buffer, in a fixed-frequency or varactor-tuned scheme. For ≥400 GHz designs, a subharmonic down-conversion mixer is integrated to facilitate spectrum measurement. At optimum bias, the measured output power was -6.2, -5.6, and -19.2 dBm, for 310.2-, 412.9-, and 573.1-GHz designs, respectively, with PDC ≤ 115 mW. Varactor-tuned designs demonstrated 10.6-12.3 GHz of tuning bandwidth up to 300 GHz.

200, 400 and 800 GHz Schottky diode "substrateless" multipliers: design and results

Several sub-millimeter doubler circuits have been designed and built using a new fabrication technology. To reduce the RF losses in the passive circuitry, the substrate under the transmission lines is etched away, leaving the metal suspended in air held by its edges on a GaAs frame. This allows the circuit to be handled and mounted easily, and makes it very robust. To demonstrate this technology, broadband balanced planar doublers have been built and tested at 400 GHz. The next generation 200, 400 and 800 GHz doublers with improved performance are also discussed. The 368-424 GHz circuits were measured and achieved 20% efficiency at 387 GHz. The 3 dB bandwidth of the fix-tuned doubler is around 9%. The maximum output power measured is around 8 mW and drops down to 1 mW at 417 GHz. This represents the highest frequency waveguide based planar doubler to date in the literature.

A broadband 800 GHz Schottky balanced doubler

A broadband planar Schottky balanced doubler at 800 GHz has been designed and built. The design utilizes two Schottky diodes in a balanced configuration on a 12 /spl mu/m thick gallium arsenide (GaAs) substrate as a supporting frame. This broadband doubler (designed for 735 GHz to 850 GHz) uses a split waveguide block and has a relatively simple, fast, and robust assembly procedure. The doubler achieved /spl ap/10% efficiency at 765 GHz, giving 1.1 mW of peak output power when pumped with about 9 mW of input power at room temperature.

A Submillimeter-Wave HEMT Amplifier Module With Integrated Waveguide Transitions Operating Above 300 GHz

In this paper, we report on the first demonstration of monolithically integrated waveguide transitions in a submillimeter-wave monolithic integrated circuit (S-MMIC) amplifier module. We designed the module for a targeted frequency range of 300-350 GHz, using WR2.2 for the input and output waveguides. The waveguide module utilizes radial -plane transitions from S-MMIC to waveguide. We designed back-to-back radial probe transitions separated by thru transmission lines to characterize the module, and have incorporated the radial -plane transitions with an S-MMIC amplifier, fabricated monolithically as a single chip. The chip makes use of an S-MMIC process and amplifier design from the Northrop Grumman Corporation, Redondo Beach, CA, using 35-nm gate-length InP transistors. The integrated module design eliminates the need for wire bonds in the RF signal path, and enables a drop-in approach for minimal assembly. The waveguide module includes a channel design, which optimizes the -plane probe bandwidth to compensate for an S-MMIC width, which is larger than the waveguide dimension, and is compatible with S-MMIC fabrication and design rules. This paper demonstrates for the first time that waveguide-based S-MMIC amplifier modules with integrated waveguide transitions can be successfully operated at submillimeter-wave frequencies.

Low noise amplifier for 180 GHz frequency band

Measurement of the humidity profile of the atmosphere is highly important for atmospheric science and weather forecasting. This sounding measurement is obtained at frequencies close to the resonance frequency of water molecules (183 GHz). We have designed and characterized a MMIC low noise amplifier that will increase the sensitivity of sounding instruments at these frequencies. This study demonstrated a factor of two improvement in MMIC LNA noise temperature at this frequency band. The measured packaged InP monolithic millimeter-wave integrated circuit (MMIC) amplifier had a noise temperature of NT=390 K (NF=3.7 dB). The circuit was fabricated in 35 nm InP high electron mobility transistor (HEMT) process.

Submillimeter-Wave InP MMIC Amplifiers From 300–345 GHz

In this letter, we describe the design, fabrication, simulation, and measured performance of a single-stage and three-stage 320 GHz amplifier using Northrop Grumman Corporations (NGC) 35-nm InP high electron mobility transistor submillimeter-wave monolithic integrated circuit (S-MMIC) process. On-wafer S-parameter measurements using an extended waveguide band WR3 vector network analyzer system were performed from 210-345 GHz. We measured 5 dB of gain for the single-stage amplifier at 340 GHz and 13-15 of gain from 300-345 GHz for the three-stage S-MMIC amplifier.

Performance of a 1.2 THz frequency tripler using a GaAs frameless membrane monolithic circuit

The first ever planar Schottky diode multiplier working over a THz will be presented in this paper. A tunerless 1.2 THz waveguide frequency tripler has been designed, fabricated and tested. The frequency multiplier consists of a 3 micron-thick GaAs frameless-membrane monolithic circuit, mounted in a split waveguide-block, which includes a built-in Picket-Potter horn. The 1.2 THz membrane tripler is driven by a 400 GHz solid-state chain composed of HEMT based power amplifiers followed by two tunerless planar diode frequency doublers. At room temperature, output power up to 80 microwatts was measured at 1126 GHz with a peak-efficiency of 0.9% and a 3 dB bandwidth of about 3.5%. The output power of the multiplier chain increased dramatically with a decrease of the ambient temperature-up to 195 microwatts was measured at 120 K. When further cooled to 50 K the chain delivers power levels as high as 250 microwatts. To the best of our knowledge, this is the first demonstration of a fully planar multiplier chain at these frequencies, along with performance that supercedes current state-of-the-art performance of whisker-contacted sources.

On-Wafer S-Parameter Measurements in the 325–508 GHz Band

We report on two-port on-wafer vector network analyzer measurements in the 325-508 GHz frequency band. Measurements are made with prototype GGB Industries Inc. WR2.2 (325-500 GHz) coplanar waveguide probes and OML Inc. WR2.2 frequency extenders. New probe performance data and characteristics of probe tip calibration using a Thru-Reflect-Line procedure are discussed. Probe S-parameter measurements indicate insertion loss per probe of 5.0 to 9.1 dB in the WR2.2 band. Calibrated dynamic range of about 30 dB or better for insertion and return loss measurement across the band is achieved. These new results for the prototype WR2.2 probes, the calibration procedure, observed errors, and results of on-wafer amplifier measurements are presented.

Miniature low noise G-band I-Q receiver

Weather forecasting, hurricane tracking and atmospheric science applications depend on humidity sounding of atmosphere. Current instruments provide these measurements from ground based, airborne and LEO satellites by measuring radiometric temperature on the flanks of the 183 GHz water vapor line. We have developed miniature low noise receivers that will enable these measurements from a geostationary thinned array sounder. This geostationary instrument is based on hundreds of low noise receivers that convert the 180 GHz signal directly to baseband in-phase and quadrature signals for digitization and correlation. The developed receivers provided a noise temperature of 450 K from 165 to 183 GHz (NF=4.1 dB) and had a mass of 3 g while consuming 24 mW of power. These are the most sensitive broadband I-Q receivers at this frequency range that operate at room temperature, and are significantly lower in mass and power consumption than previously reported receivers.

Medium power amplifiers covering 90-130 GHz for the ALMA telescope local oscillators

This paper describes a set of power amplifier (PA) modules containing InP high electron mobility transistor (HEMT) monolithic millimeter-wave integrated circuit (MMIC) chips. The chips were designed and optimized for local oscillator sources in the 90-130 GHz band for the Atacama large millimeter array telescope. The modules feature 20-45 mW of output power, to date the highest power from solid state HEMT MMIC modules above 110 GHz.