Piotr Starski

Cryogenic wide-band ultra-low-noise IF amplifiers operating at ultra-low DC power

This paper describes cryogenic broad-band amplifiers with very low power consumption and very low noise for the 4-8-GHz frequency range. At room temperature, the two-stage InP-based amplifier has a gain of 27 dB and a noise temperature of 31 K with a power consumption of 14.4 mW per stage, including bias circuitry. When cooled to 15 K, an input noise temperature of 1.4 K is obtained at 5.7 mW per stage. At 0.51 mW per stage, the input noise increases to 2.4 K. The noise measurements have been repeated at different laboratories using different methods and are found consistent.

On the performance of low-noise low-DC-power-consumption cryogenic amplifiers

The performance of broad-band low-noise low-dc-power-consumption cryogenic amplifiers have been studied in detail with emphasis on minimizing the power consumption and optimizing the amplifier performance at cryogenic temperature. A general approach is presented for the modeling and amplifier design, which helps in minimizing the power consumption and optimizing the performance of the amplifier. A noise temperature below 9 K and 22-dB gain was experimentally obtained in the frequency range of 4-8 GHz with a total power consumption of 4 mW with commercial GaAs transistors.

Electrically conductive adhesives at microwave frequencies

In this paper we present results from measurements on epoxy-based anisotropic and isotropic, electrically conductive adhesives, ACAs and ICAs respectively. We study two different types of connections, a flip-chip bonded silicon test chips and a simple transmission line gap bridged by a copper foil. These measurements are referenced to equivalent solder joints. The silicon chip is a standard test chip. The test chips are mounted on three different substrates, a rigid FR-4 board, flexible board and a high-frequency Teflon-based duroid substrate. We also discuss two electrical models for the connections, an equivalent RC model and a stochastic model, based on random particle distribution. The equivalent electrical model is based on physical considerations and the parameters are then fitted to measurement data in the high frequency CAD tool HP MDS. All the adhesive and solder interconnections are measured before and after temperature cycling and humidity tests. The temperature dependence of the connections S-parameters are also studied in a temperature controlled environment. A HP8510 network analyzer is used to measure scattering parameters. On rigid and flexible boards, the frequency range investigated is 500 MHz to 8 GHz, and on duroid mounted flip-chips and bridges, the range is 1 GHz to 30 GHz. The Thru-Reflect-Line calibration procedure is used to get the best possible calibration. Power testing is used with the Cu bridge assembly to find the maximum power transmission through an electrically conductive adhesive interconnect. This is done at relevant microwave frequencies. Results indicate that the isotropic adhesive interconnections handle high power throughput well. The adhesive joints are subjected to a maximum peak pulsed power of 250 W. Maximum work factor of the pulsed signal is 10%. The effects of different particle sizes and materials in the ACAs are systematically investigated. Three different particle sizes and two particle materials are examined. All adhesives considered show similar electrical properties and are all suitable for adhesive electrical interconnections. The microstructure of the adhesive joints is studied by cross-sectioning using Scanning Electron Microscopy (SEM) before and after temperature cycling.

InP HEMT-based, cryogenic, wideband LNAs for 4-8 GHz operating at very low DC-power

We present cryogenic broadband amplifiers for 4-8 GHz with very low dc-power consumption and low noise. Two different amplifiers were designed and manufactured, one of which was based on in-house InP devices and the other on commercial GaAs devices. When cooled to 15 K, the InP-based amplifier shows an input noise temperature of 3.9 K at a dc-power consumption of 3.7 mW. The GaAs-based amplifier shows an input noise temperature of 6.5 K at a dc-power consumption of 23 mW.

On the performance of low DC power consumption cryogenic amplifiers

The performance of broadband, low-noise, low DC consumption cryogenic amplifiers was studied in detail with emphasis on minimizing the power consumption and optimizing the amplifier performance at cryogenic temperature. A comprehensive approach used in the modelling and amplifier design can help one to minimize the power consumption and optimize the performance of the amplifier. An 8.5 K average noise temperature and 24 dB gain were experimentally obtained in the frequency range 4-8 GHz with total power consumption of 4 mW for a 2-stage design with commercial GaAs transistors.

InGaAs-InAlAs-InP HEMT technology for ultra-high frequency and ultra-low noise performance

InGaAs-InAlAs-InP HEMT is facing competition from the emerging MHEMT technology. Nonetheless, for top-performing applications requiring high gain and low noise, InP HEMT is still the preferred choice. We here present results from InP HEMT development for sub-100 nm gate length designs yielding f/sub max/ above 400 GHz and ultra-low noise hybrid amplifiers with a minimum noise temperature of 1.1 K when operated under cryogenic conditions.

Two-finger InP HEMT design for stable cryogenic operation of ultra-low-noise Ka-band LNAs

We have investigated the cryogenic stability of two-finger InP HEMTs aimed for Ka-band ultra-low noise amplifiers (LNAs). Unlike two-finger transistors with a large gate-width above 2 χ 50 μm, the transistors with a small gate-width exhibit unstable cryogenic behavior. The instability is suppressed by adding a source air-bridge. The stabilizing effect of the air-bridge is demonstrated both on device and circuit level. A three-stage 2440 GHz monolithic microwave integrated circuit (MMIC) LNA using a stabilized 100-nm HEMT technology is presented. The amplifier achieves a record noise temperature of 7 K at 25.6 GHz with an average noise of 10.6 K across the whole band at an ambient temperature of 5.5 K. The amplifier gain is 29 dB ± 0.6 dB exhibiting very stable and repeatable operation. To our knowledge, this amplifier presents the lowest noise temperature reported so far for InP cryogenic LNAs covering the Ka-band.

High frequency interconnections using electrically conductive adhesives

Results from measurements and simulation of high frequency interconnections are used to obtain an electrical model of the adhesive joint based on the physical parameters involved. Isotropically conductive adhesive joints can be used at microwave frequencies at least up to 30 GHz. Results indicate that the electrical performance of these connections is comparable to that of solder joints.

Novel Devices for (Sub)millimeter-Wave Space Applications

Submillimeter-wave space applications require special components for power generation, detection and multiplication. This article presents recent progress in three various solid-state device technologies for submillimeter-wave space instruments: the InP HEMT for ultra-low noise detection at very low power in the IF amplifier, the heterostructure barrier varactor in the frequency multiplier, and the superconducting hot electron bolometer mixer for quantum-limited heterodyne detection above 700 GHz.