| 1. |
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| 2. |
- Abbasi, Morteza, 1982, et al.
(författare)
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Single-Chip 220-GHz Active Heterodyne Receiver and Transmitter MMICs With On-Chip Integrated Antenna
- 2011
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 59:2, s. 466-478
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the design and characterization of single-chip 220-GHz heterodyne receiver (RX) and transmitter (TX) monolithic microwave integrated circuits (MMICs) with integrated antennas fabricated in 0.1-mu m GaAs metamorphic high electron-mobility transistor technology. The MMIC receiver consists of a modified square-slot antenna, a three-stage low-noise amplifier, and a sub-harmonically pumped resistive mixer with on-chip local oscillator frequency multiplication chain. The transmitter chip is the dual of the receiver chip by inverting the direction of the RF amplifier. The chips are mounted on 5-mm silicon lenses in order to interface the antenna to the free space and are packaged into two separate modules. The double-sideband noise figure (NF) and conversion gain of the receiver module are measured with the Y-factor method. The total noise temperature of 1310 +/- 100K(corresponding to an NF of 7.4 dB), including the losses in the lens and antenna, is measured at 220 GHz with a respective conversion gain of 3.5 dB. The radiated continuous-wave power from the transmitter module is measured to be up to -6 dBm from 212 to 226 GHz. The transmitter and receiver are linked in a quasi-optical setup and the IF to IF response is measured to be flat up to 10 GHz. This is verified to be usable for transmission of a 12.5-Gb/s data stream between the transmit and receive modules over a 0.5-m wireless link. The modules operate with a 1.3-V supply and each consume 110-mW dc power. The presented 220-GHz integrated circuits and modules can be used in a variety of applications, including passive and active imaging, as well as high-speed data communications. To the best of our knowledge, these MMICs are the highest frequency single-chip low-noise heterodyne receiver and transmitter pair reported to date.
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| 3. |
- Bower, G. C., et al.
(författare)
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THE ALLEN TELESCOPE ARRAY Pi GHz SKY SURVEY. I. SURVEY DESCRIPTION AND STATIC CATALOG RESULTS FOR THE BOOTES FIELD
- 2010
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 725:2, s. 1792-1804
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Tidskriftsartikel (refereegranskat)abstract
- The Pi GHz Sky Survey (PiGSS) is a key project of the Allen Telescope Array. PiGSS is a 3.1 GHz survey of radio continuum emission in the extragalactic sky with an emphasis on synoptic observations that measure the static and time-variable properties of the sky. During the 2.5 year campaign, PiGSS will twice observe similar to 250,000 radio sources in the 10,000 deg(2) region of the sky with b > 30 degrees to an rms sensitivity of similar to 1 mJy. Additionally, sub-regions of the sky will be observed multiple times to characterize variability on timescales of days to years. We present here observations of a 10 deg(2) region in the Bootes constellation overlapping the NOAO Deep Wide Field Survey field. The PiGSS image was constructed from 75 daily observations distributed over a 4 month period and has an rms flux density between 200 and 250 mu Jy. This represents a deeper image by a factor of 4-8 than we will achieve over the entire 10,000 deg(2). We provide flux densities, source sizes, and spectral indices for the 425 sources detected in the image. We identify similar to 100 new flat-spectrum radio sources; we project that when completed PiGSS will identify 10(4) flat-spectrum sources. We identify one source that is a possible transient radio source. This survey provides new limits on faint radio transients and variables with characteristic durations of months.
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| 4. |
- Cano, J. L., et al.
(författare)
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Ultra-Wideband Chip Attenuator for Precise Noise Measurements at Cryogenic Temperatures
- 2010
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 58:9, s. 2504-2510
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A 20-dB chip attenuator designed for cryogenic noise measurements from dc up to 40 GHz is presented. The chip is based on the use of temperature-stable tantalum-nitride thin-film resistors, a high thermal conductivity substrate such as crystal quartz (z-cut), and a suitable design that avoids inner conductor thermal heating, which is an important limiting factor for the precision of cryogenic noise measurements. A high-accuracy temperature sensor installed inside the attenuator module provides precise temperature characterization close to the chip location. The high thermal conductivity of the chip substrate in the designed attenuator assures a negligible temperature gradient between the resistive elements in the chip and the sensor, thus improving the measurement accuracy. The attenuator also shows an excellent electrical performance with insertion losses of 19.9 dB +/- 0.65 dB and return losses better than 20.6 dB in the whole frequency range at 296 K. The insertion loss change when cooled to 15 K is less than 0.25 dB, which demonstrates its temperature stability.
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| 5. |
- Cha, Eunjung, 1985, et al.
(författare)
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0.3-14 and 16-28 GHz Wide-Bandwidth Cryogenic MMIC Low-Noise Amplifiers
- 2018
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 66:11, s. 4860-4869
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Tidskriftsartikel (refereegranskat)abstract
- We present two monolithic microwave integrated circuit (MMIC) cryogenic broadband low-noise amplifiers (LNAs) based on the 100 nm gate length InP high-electron mobility transistor technology for the frequency range of 0.3-14 and 16-28 GHz. The 0.3-14 GHz three-stage LNA exhibited a gain of 41.6 ± 1.4 dB and an average noise temperature of 3.5 K with a minimum noise temperature of 2.2 K at 6 GHz when cooled down to 4 K. The 16-28 GHz three-stage LNA showed a gain of 32.3 ± 1.8 dB and an average noise temperature of 6.3 K with a minimum noise temperature of 4.8 K at 20.8 GHz at the ambient temperature of 4 K. This is the first demonstration of cryogenic MMIC LNA covering the whole K-band. To the best of the authors' knowledge, the cryogenic MMIC LNAs demonstrated the state-of-the-art noise performance in the 0.3-14 and 16-28 GHz frequency range.
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| 6. |
- Cha, Eunjung, 1985, et al.
(författare)
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A 300-mu W Cryogenic HEMT LNA for Quantum Computing
- 2020
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Ingår i: PROCEEDINGS OF THE 2020 IEEE/MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM (IMS). - 0149-645X .- 2576-7216. - 9781728168159 ; , s. 1299-1302
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Konferensbidrag (refereegranskat)abstract
- This paper reports on ultra-low power 4-8 GHz (C-band) InP high-electron mobility transistor (HEMT) cryogenic low-noise amplifiers (LNAs) aimed for qubit amplification in quantum computing. We have investigated dc power dissipation in hybrid three-stage cryogenic LNAs using 100-nm gate length InP HEMTs with different indium content in the channel (65% and 80%). The noise performance at 300 K was found to be comparable for both channel structures. At 5 K, an LNA with 65% indium channel exhibited significantly lower noise temperature at any dc power dissipation compared to the LNA with 80% indium channel. The LNA with 65% indium channel achieved an average noise of 3.2 K with 23 dB gain at an ultra-low power consumption of 300 mu W. To the best of authors' knowledge, the LNA exhibited the lowest noise temperature to date for sub-milliwatt power cryogenic C-band LNAs.
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| 7. |
- Cha, Eunjung, 1985, et al.
(författare)
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Cryogenic low-noise InP HEMTs: A source-drain distance study
- 2016
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Ingår i: 2016 Compound Semiconductor Week, CSW 2016. - 9781509019649 ; , s. Article number 7528576-
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Konferensbidrag (refereegranskat)abstract
- The scaling effect of the source-drain distance was investigated in order to improve the performance of low-noise InP HEMTs at cryogenic temperatures 4-15 K. The highest dc transconductance at an operating temperature of 4.8 K and low bias power was achieved at a source-drain distance of 1.4 mu m. The extracted HEMT minimum noise temperature was 0.9 K at 5.8 GHz for a 3-stage 4-8 GHz hybrid low-noise amplifier at 10 K.
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| 8. |
- Cha, Eunjung, 1985, et al.
(författare)
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InP HEMTs for Sub-mW Cryogenic Low-Noise Amplifiers
- 2020
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 41:7, s. 1005-1008
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on a 100-nm gate length InP high-electron-mobility transistor (HEMT) technology for cryogenic low-noise amplifiers (LNAs) with ultra-low power dissipation of 112 mu W. This result was obtained by using 100-nm gate length InP HEMTs with improved transconductance at low drain current through a scaled-down gate-channel distance while maintaining a low gate leakage current with the use of an InP etch stop layer and Pt gate metal. The noise performance of InP HEMTs was demonstrated in a 4-8 GHz (C-band) three-stage hybrid LNA at the ambient temperature of 5 K. At a dc power dissipation of 300 mu W, the average noise temperature was 2.8 K with 27 dB gain. At a dc power dissipation of 112 mu W, the LNA exhibited an average noise temperature of 4.1 K with a gain of 20 dB. The presented results demonstrate the large potential of InP HEMT technology for sub-mW cryogenic LNA design.
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| 9. |
- Cha, Eunjung, 1985, et al.
(författare)
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Optimization of Channel Structures in InP HEMT Technology for Cryogenic Low-Noise and Low-Power Operation
- 2023
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Ingår i: IEEE Transactions on Electron Devices. - 1557-9646 .- 0018-9383. ; 70:5, s. 2431-2436
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Tidskriftsartikel (refereegranskat)abstract
- We report the impact from channel composition on the cryogenic low-noise performance at low dc power for a 100-nm gate-length InGaAs-InAlAs-InP high-electron mobility transistor (HEMT). Two indium (In) channel compositions, 65% and 80%, were studied by dc and RF characterization at 300 and 5 K. For the cryogenic low-noise optimization, it was important to increase the transconductance to gate–source capacitance ratio in the weak inversion region implying that a higher maximum cutoff frequency in the HEMT does not guarantee lower noise. The HEMT noise performance was obtained from noise measurements in a hybrid three-stage 4–8-GHz ( $\textit{C}$ -band) low-noise amplifier (LNA) down to 300- $\mu$ W dc power dissipation. While the HEMT LNA noise performance for both the channel compositions at 300 K was found to be comparable, the HEMT LNA at 5 K with 65% In channel showed a minimum noise temperature of 1.4 K, whereas the noise temperature in the HEMT LNA with 80% In channel HEMTs increased to 2.4 K. The difference in the noise became more pronounced at reduced dc power dissipation. The ultralow dc power of 300 $\mu$ W demonstrated for a cryogenic $\textit{C}$ -band LNA with an average noise temperature of 2.9 K and 24-dB gain is of interest for future qubit read-out electronics at 4 K.
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| 10. |
- Cha, Eunjung, et al.
(författare)
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Two-Finger InP HEMT Design for Stable Cryogenic Operation of Ultra-Low-Noise Ka-and Q-Band LNAs
- 2017
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Ingår i: IEEE transactions on microwave theory and techniques. - : Institute of Electrical and Electronics Engineers Inc.. - 0018-9480 .- 1557-9670. ; 65:12, s. 5171-5180
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the cryogenic stability of two-finger 100-nm gate-length InP HEMTs aimed for Ka-and Q-band ultra-low noise amplifiers (LNAs). InP HEMTs with unit gate widths ranging between 30 and 50 mu text{m} exhibit unstable cryogenic behavior with jumps in drain current and discontinuous peaks in transconductance. We also find that shorter gate length enhances the cryogenic instability. We demonstrate that the instability of two-finger transistors can be suppressed by either adding a source air bridge, connecting the back end of gates, or increasing the gate resistance. A three-stage 24-40 GHz and a four-stage 28-52-GHz monolithic microwave-integrated circuit LNA using the stabilized InP HEMTs are presented. The Ka-band amplifier achieves a minimum noise temperature of 7 K at 25.6 GHz with an average noise temperature of 10.6 K at an ambient temperature of 5.5 K. The amplifier gain is 29 dB ± 0.6 dB. The Q-band amplifier exhibits minimum noise temperature of 6.7 K at 32.8 GHz with average noise temperature of 10 K at ambient temperature of 5.5 K. The amplifier gain is 34 dB ± 0.8 dB. To our knowledge, the Ka-and Q-band amplifiers demonstrate the lowest noise temperature reported so far for InP cryogenic LNAs. © 1963-2012 IEEE.
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