Planar GaAs Schottky Diodes Research Articles

1.1 THz tenth harmonic mixer based on planar GaAs Schottky diode

Here, the tenth harmonic mixing technology based on planar GaAs Schottky diode is first proposed for the 1.1 terahertz (THz) frequency conversion module. The first higher order mode cut-off frequency of the suspended microstrip line has been investigated to determine the appropriate cross-sectional dimension of transmission line shield cavity in the radio frequency (RF) circuit portion. The height of shield cavity of transmission line is designed to be discontinuous in order to facilitate the assembly of the diode. A modelling approach combining field and circuit is used to achieve joint simulation of linear passive structure and diode non-linear characteristics. The simulation results show that the frequency conversion loss of this mixer is <55 dB in the RF frequency range of 1.03–1.154 THz, and the best frequency conversion loss is 50 dB at RF of 1.098 THz.

An Improved 110–130-GHZ Fix-Tuned Subharmonic Mixer with Compact Microstrip Resonant Cell Structure

This paper presents the design and fabrication of an improved low-loss 110–130 GHz subharmonically pumped mixer with planar Schottky diodes fabricated by Virginia Diodes Inc. The antiparallel pair of planar GaAs Schottky diodes flip-chipped onto a suspended microstrip is fully integrated with a radio frequency (RF) and an intermediate frequency (IF) filter. A compact microstrip resonant cell (CMRC) filter is for the first time introduced in a submillimeter mixer to replace the traditional low-and-high-impedance microstrip RF filter. The shorter size and wider stop-band of the CMRC filter improved the performance of the subharmonic mixer. The best single-sideband (SSB) conversion loss of 7.7 dB was achieved with 3.5 mW of local oscillator (LO) power at a fixed 59 GHz of LO frequency. Over an RF band of 20 GHz, the SSB conversion loss is below 11 dB.

A Broadband 835–900-GHz Fundamental Balanced Mixer Based on Monolithic GaAs Membrane Schottky Diodes

The development of a 835-900-GHz biasable fundamental balanced mixer using planar GaAs Schottky diodes is presented. The monolithic microwave integrated circuit integrates two planar Schottky anodes in a balanced configuration, stripline filtering elements, and on-chip capacitor on a thin GaAs membrane. At 850 GHz, double side-band (DSB) mixer noise temperature of 2660 K and conversion loss of 9.25 dB are measured, respectively, at room temperature. When the mixer is cooled to 120 K, the DSB mixer noise temperature and conversion loss improve to 1910 K and 8.84 dB, respectively.

Improved 240-GHz subharmonically pumped planar Schottky diode mixers for space-borne applications

Low-noise broad intermediate frequency (IF) band 240-GHz subharmonically pumped planar Schottky diode mixers for space-borne radiometers have been developed and characterized. The planar GaAs Schottky diodes are fully integrated with the RF/IF filter circuitry via the quartz-substrate upside-down integrated device (QUID) process resulting in a robust and easily handled package. A best double-sideband-mixer noise temperature of 490 K was achieved with 3 mW of local-oscillator power at 2-GHz IF. Over an IF band of 1.5-10 GHz, the noise temperature is below 1000 K. This state-of-the-art performance is attributed to lower parasitic capacitance devices and a low-loss waveguide circuit. Device fabrication technology and the resulting RF mixer performance obtained in the 200-250-GHz frequency range will be described.

A 335 GHz quasi-optical Schottky receiver

A quasi-optical Schottky receiver based on an integrated planar antenna-mixer structure has been developed and tested at 335 GHz. The receiver antenna is based on the quasi-integrated horn antenna with 23 dB directivity. At room temperature, the measured DSB antenna-mixer conversion loss and noise temperature at 335 GHz are 8.5 dB and 1750 K, respectively. This simple and tunerless design has a noise figure within 1 dB of the best tuned room temperature waveguide mixer using a similar planar GaAs Schottky diode.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A 250 GHz planar low noise Schottky receiver

A planar quasi-optical Schottky receiver based on the quasi-integrated horn antenna has been developed and tested over the 230–280GHz bandwidth. The receiver consists of a planar GaAs Schottky diode placed at the feed of a dipole-probe suspended on a thin dielectric membrane in an etched-pyramidal horn cavity. The diode has a 1.2Μm anode diameter and a low parasitic capacitance due to the use of an etched surface channel. The antenna-mixer results in a measured DSB conversion loss and noise temperature at 258GHz of 7.2dB±0.5dB and 1310K±70K, respectively, at room temperature. The design is compatible with SIS mixers, and the low cost of fabrication and simplicity makes it ideal for submillimeter-wave imaging arrays requiring a 10–20% bandwidth.

An 86-106 GHz quasi-integrated low noise Schottky receiver

An integrated planar receiver has been developed and tested over the 82-112 GHz bandwidth. The quasi-integrated antenna used in the receiver has a high gain, a high Gaussian coupling efficiency and a wide bandwidth. The mixer design consists of a planar GaAs Schottky diode placed at the feed of a dipole probe suspended inside an integrated horn antenna. The diode uses an etched surface channel and a planar air bridge for reduced parasitic capacitance. At 92 GHz, the room temperature antenna-mixer exhibits a double sideband (DBS) conversion loss and noise temperature of 5.5+or-0.5 Db and 770 K+or-50 K, respectively. The measured DSB conversion loss, and noise temperature over a 20-GHz bandwidth (86-106 GHz) remain less than 6.2+or-0.5 dB and 1000 K+or-50 K, respectively. The low cost of fabrication and simplicity of the design makes it ideal for millimeter- and submillimeter-wave receivers.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A novel planar diode mixer for submillimeter-wave applications

A mixer employing a planar GaAs Schottky diode has been designed and tested over a 300-365 GHz bandwidth. Using a planar diode eliminates the disadvantages of mechanical instability and labor-intensive assembly associated with conventional whisker-contacted diodes. The mixer design process uses scale model impedance measurements for both the design of individual components and the measurement of impedances presented to the diode terminals by the mixer mount at fundamental and harmonic frequencies. Results from these impedance measurements are used in linear and nonlinear numerical mixer analyses to predict the mixer performance.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>