We present an overview of solid-state integrated circuit amplifiers approaching terahertz frequencies based on the latest device technologies which have emerged in the past several years. Highlights ...include the best reported data from heterojunction bipolar transistor (HBT) circuits, high electron mobility transistor (HEMT) circuits, and metamorphic HEMT (mHEMT) amplifier circuits. We discuss packaging techniques for the various technologies in waveguide modules and describe the best reported noise figures measured in these technologies. A consequence of THz transistors, namely ultra-low-noise at cryogenic temperatures, will be explored and results presented. We also present a short review of power amplifier technologies for the THz regime. Finally, we discuss emerging materials for THz amplifiers into the next decade.
Millimeter and submillimeter indium phosphide (InP) microwave monolithic integrated circuits (MMICs) are increasingly used in applications spanning Earth science, astrophysics, and defense. In this ...paper, we characterize direct detection and heterodyne gain fluctuations of 35-, 30-, and 25-nm gate-length InP MMIC low-noise amplifiers (LNAs) designed for the 200-670-GHz frequency range. Of the twelve MMIC LNAs, five pairs have also been measured in multistage or cascaded configuration. In direct detection mode, the MMICs room temperature (RT) 1/f noise spectrum and responsivity were measured. From these the power spectral density, the noise equivalent temperature difference (NETD), equivalent system noise temperature (T sys DD ), and low-frequency normalized gain fluctuations (ΔG/G) are derived. On the same set of MMIC LNAs, using a heterodyne down conversion technique, the Allan variance method is applied to obtain the Allan stability time and normalized 4-8 GHz gain fluctuation noise at both RT and two cryogenic temperatures. We find in the case of 35-, 30-, and 25-nm gate-length InP MMIC LNAs that the derived direct detection and heterodyne gain stability is highly process dependent with only a secondary dependence on gate periphery, the number of gate fingers, and/or gain stages. This observation confirms the underlying solid-state physics understanding that gain fluctuation noise is the result of a temporal distribution of the generation and recombination of electron free carriers due to lattice defects and surface impurities. Upon cooling below ~66 K, it is observed that on average gain fluctuations increase by ≳2.2× and the Allan stability time decreases by ~2.5×. The presented measurement results compare favorably
In this paper, we describe a miniature power-combiner for monolithic millimeter-wave integrated circuit (MMIC) chips using spatial power-combining with cavity modes. We have designed GaN MMIC power ...amplifier chips for 94 GHz, and illustrate the concept of the W-Band Spatial Power Combining Amplifier (WSPCA). Using 1 Watt, 94 GHz MMIC chips in a two-way cavity mode combiner, we were able to achieve 2 Watts of output power with 9 dB gain and 15 % PAE. This technique could be extended to high power MMICs and larger numbers of chips to achieve higher output power in a compact size. Current applications include earth science radar, and may be extended to other applications requiring wider bandwidth.
In this paper, we describe a miniature power-combiner for monolithic millimeter-wave integrated circuit (MMIC) chips using spatial power-combining with cavity modes. We have designed GaN MMIC power ...amplifier chips for 94 GHz, and illustrate the concept of the W-Band Spatial Power Combining Amplifier (WSPCA). Using 1 Watt, 94 GHz MMIC chips in a two-way cavity mode combiner, we were able to achieve 2 Watts of output power with 9 dB gain and 15 % PAE. This technique could be extended to high power MMICs and larger numbers of chips to achieve higher output power in a compact size. Current applications include earth science radar, and may be extended to other applications requiring wider bandwidth.
A low Terahertz (324 GHz) frequency generator is realized in 90 nm CMOS by linearly superimposing quadruple (N=4) phase shifted fundamental signals at one fourth of the output frequency (81 GHz). The ...developed technique minimizes the fundamental, second and third order harmonics without extra filtering and results in a high fundamental-to-4 th harmonic signal conversion ratio of 0.17 or -15.4 dB. The demonstrated prototype produces a calibrated -46 dBm output power when biased at 1 V and 12 mA with 4 GHz tuning range and extrapolated phase noise of -91 dBc/Hz at 10 MHz frequency offset. The linear superposition (LS) technique can be generalized for all even number cases (N=2k, where k=1,2,3,4,...,n) with different tradeoffs in output power and frequency. As CMOS continues to scale, we anticipate the LS N=4 VCO to generate signals beyond 2 Terahertz by using 22 nm CMOS and produce output power up to -1.5 dBm with 1.7% power added efficiency with an LS VCO + Class-B Power Amplifier cascaded circuit architecture.
Existing spaceborne radiometer receivers, particularly below 40GHz, have typically utilized analog direct detection, but recently have been pushing toward heterodyne systems with digital signal ...processing to deal with the problem of radio frequency interference (RFI). But, radar and radiometer receivers have yet to be integrated in an optimized manner for spaceborne systems. Fast sampling analog-to-digital converters (ADCs) have been evolving to where we can consider in the 2025 time frame digitizing broad IF signals containing the desired radar signal, natural brightness emission and extraneous man-made RF signals (e.g. RFI) which can then be distributed and processed by radar and radiometer specific digital processors. In this way, a common RF front-end architecture can interface with an agile reconfigurable backend and can be used across several systems (e.g. small, large class sensors). In this study, we designed and demonstrated a multi-purpose receiver that can serve both the needs for the radar and radiometer, first focusing on Ka-band.
V-band MMIC LNAs and mixers for observing the early universe Samoska, Lorene A.; Varonen, Mikko; Kangaslahti, Pekka ...
2016 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz),
2016-Sept.
Conference Proceeding
We have developed V-Band (50-75 GHz) monolithic millimeter-wave integrated circuit (MMIC) low noise amplifiers using NGC's 35 nm InP HEMT technology. The MMIC LNAs exhibit noise temperatures of ...150-270K over the full waveguide band. Subharmonic MMIC mixers were also developed using United Monolithic Semiconductor's GaAs Schottky diode process, and cover V-band with 15-21 dB conversion loss. These components form the front end of receivers that could be used for radio astronomy. While much of V-Band is opaque to the atmosphere, a future space probe to map the intensity of carbon monoxide (CO) in V-band would help astronomers understand the early universe.
We present deep CCS and HC7N observations of the L1495-B218 filaments in the Taurus molecular cloud obtained using the K-band focal plane array on the 100 m Green Bank Telescope. We observed the ...L1495-B218 filaments in CCS JN = 21-10 and HC7N J = 21−20 with a spectral resolution of 0.038 km s−1 and an angular resolution of 31″. We observed strong CCS emission in both evolved and young regions and weak emission in two evolved regions. HC7N emission is observed only in L1495A-N and L1521D. We find that CCS and HC7N intensity peaks do not coincide with NH3 or dust continuum intensity peaks. We also find that the fractional abundance of CCS does not show a clear correlation with the dynamical evolutionary stage of dense cores. Our findings and chemical modeling indicate that the fractional abundances of CCS and HC7N are sensitive to the initial gas-phase C/O ratio, and they are good tracers of young condensed gas only when the initial C/O is close to solar value. Kinematic analysis using multiple lines, including NH3, HC7N, CCS, CO, HCN, and HCO+, suggests that there may be three different star formation modes in the L1495-B218 filaments. At the hub of the filaments, L1495A/B7N has formed a stellar cluster with large-scale inward flows (fast mode), whereas L1521D, a core embedded in a filament, is slowly contracting because of its self-gravity (slow mode). There is also one isolated core that appears to be marginally stable and may undergo quasi-static evolution (isolated mode).
In this letter, a rectangular waveguide to conductor backed-coplanar waveguide electromagnetic transition suitable of operating at sub-millimeter wave frequencies is demonstrated. The dipole based ...transition is fabricated using InP monolithic microwave integrated circuit technology. The compact transition eliminates wire-bonding problems (return loss and insertion loss) and is suitable for direct integration of sub-millimeter wave monolithic integrated circuits. Measured transition loss of ~1 dB has been achieved in the frequency range of 340 to 380 GHz.
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