Artificial transmission lines, realized using standard passive components of the foundry library, were utilized to design 180-degree baluns for millimetre wave frequency doublers. Monolithic ...integration of the complete doubler was achieved on extremely small chip area, 0.6mm2. However, the performance of the frequency doubler was not sacrificed, since the operating frequency bandwidth was 30 %. These results show the suitability of this new technique for integration of several of the functions of a transmit/receive unit economically on a very small area on chip.
The Q/U Imaging ExperimenT (QUIET) has observed the cosmic microwave background (CMB) at 43 and 95GHz. The 43-GHz results have been published in QUIET Collaboration et al. (2011), and here we report ...the measurement of CMB polarization power spectra using the 95-GHz data. This data set comprises 5337 hours of observations recorded by an array of 84 polarized coherent receivers with a total array sensitivity of 87 uK sqrt(s). Four low-foreground fields were observed, covering a total of ~1000 square degrees with an effective angular resolution of 12.8', allowing for constraints on primordial gravitational waves and high-signal-to-noise measurements of the E-modes across three acoustic peaks. The data reduction was performed using two independent analysis pipelines, one based on a pseudo-Cl (PCL) cross-correlation approach, and the other on a maximum-likelihood (ML) approach. All data selection criteria and filters were modified until a predefined set of null tests had been satisfied before inspecting any non-null power spectrum. The results derived by the two pipelines are in good agreement. We characterize the EE, EB and BB power spectra between l=25 and 975 and find that the EE spectrum is consistent with LCDM, while the BB power spectrum is consistent with zero. Based on these measurements, we constrain the tensor-to-scalar ratio to r=1.1+0.9-0.8 (r<2.8 at 95% C.L.) as derived by the ML pipeline, and r=1.2+0.9-0.8 (r<2.7 at 95% C.L.) as derived by the PCL pipeline. In one of the fields, we find a correlation with the dust component of the Planck Sky Model, though the corresponding excess power is small compared to statistical errors. Finally, we derive limits on all known systematic errors, and demonstrate that these correspond to a tensor-to-scalar ratio smaller than r=0.01, the lowest level yet reported in the literature.
The Q/U Imaging ExperimenT (QUIET) employs coherent receivers at 43GHz and 95GHz, operating on the Chajnantor plateau in the Atacama Desert in Chile, to measure the anisotropy in the polarization of ...the CMB. QUIET primarily targets the B modes from primordial gravitational waves. The combination of these frequencies gives sensitivity to foreground contributions from diffuse Galactic synchrotron radiation. Between 2008 October and 2010 December, >10,000hours of data were collected, first with the 19-element 43GHz array (3458hours) and then with the 90-element 95GHz array. Each array observes the same four fields, selected for low foregrounds, together covering ~1000deg^2. This paper reports initial results from the 43GHz receiver which has an array sensitivity to CMB fluctuations of 69uK sqrt(s). The data were extensively studied with a large suite of null tests before the power spectra, determined with two independent pipelines, were examined. Analysis choices, including data selection, were modified until the null tests passed. Cross correlating maps with different telescope pointings is used to eliminate a bias. This paper reports the EE, BB and EB power spectra in the multipole range ell=25-475. With the exception of the lowest multipole bin for one of the fields, where a polarized foreground, consistent with Galactic synchrotron radiation, is detected with 3sigma significance, the E-mode spectrum is consistent with the LCDM model, confirming the only previous detection of the first acoustic peak. The B-mode spectrum is consistent with zero, leading to a measurement of the tensor-to-scalar ratio of r=0.35+1.06-0.87. The combination of a new time-stream double-demodulation technique, Mizuguchi-Dragone optics, natural sky rotation, and frequent boresight rotation leads to the lowest level of systematic contamination in the B-mode power so far reported, below the level of r=0.1
Broadband Predistortion Linearisers Kangaslahti, P.; Ruokokoski, L.; Pohjalainen, J. ...
2001 31st European Microwave Conference,
2001-Sept.
Conference Proceeding
Digital communications place ever-increasing demands on the linearity of power amplifiers. To meet these challenges, the system engineer needs to either increase the maximum output power of the ...amplifier, if the DC power or thermal limitations allow this, or improve the linearity of the amplifier. We have developed very broadband predistortion linearisers for traveling wave tube amplifiers (TWTA). These predistortion linearisers are based on only two custom MMICs and operate at S,C, Ku, K and Ka frequency bands, thus covering the most important frequency bands currently in use.
A set of monolithic microwave integrated circuits for millimeter-wave radio front end was developed. The circuits operate in the 60-63 GHz frequency range and have been fabricated with a commercially ...available 0.15-μm GaAs PHEMT technology. Designed, fabricated and measured circuits reported here are a general-purpose medium power amplifier, a low noise amplifier and signal generation circuits for generation of the 56 GHz local oscillator signal. Excellent measured performance was obtained. The MPA delivers 16 dBm of output power along with a gain of 12 dB. Measured LNA noise figure at 60 GHz is 5 dB and the gain is 18 dB. The mixer in up-conversion configuration exhibited 12 dB conversion loss.
The scientific performance of the Planck Low Frequency Instrument (LFI) after one year of in-orbit operation is presented. We describe the main optical parameters and discuss photometric calibration, ...white noise sensitivity, and noise properties. A preliminary evaluation of the impact of the main systematic effects is presented. For each of the performance parameters, we outline the methods used to obtain them from the flight data and provide a comparison with pre-launch ground assessments, which are essentially confirmed in flight.
The QUIET Instrument QUIET Collaboration; Bischoff, C; Brizius, A ...
arXiv.org,
07/2012
Paper, Journal Article
Odprti dostop
The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the Cosmic Microwave Background, targeting the imprint of inflationary gravitational waves at large angular scales (~ 1 ...degree). Between 2008 October and 2010 December, two independent receiver arrays were deployed sequentially on a 1.4 m side-fed Dragonian telescope. The polarimeters which form the focal planes use a highly compact design based on High Electron Mobility Transistors (HEMTs) that provides simultaneous measurements of the Stokes parameters Q, U, and I in a single module. The 17-element Q-band polarimeter array, with a central frequency of 43.1 GHz, has the best sensitivity (69 uK sqrt(s)) and the lowest instrumental systematic errors ever achieved in this band, contributing to the tensor-to-scalar ratio at r < 0.1. The 84-element W-band polarimeter array has a sensitivity of 87 uK sqrt(s) at a central frequency of 94.5 GHz. It has the lowest systematic errors to date, contributing at r < 0.01. The two arrays together cover multipoles in the range l= 25-975. These are the largest HEMT-based arrays deployed to date. This article describes the design, calibration, performance of, and sources of systematic error for the instrument.
We have developed noise sources at 90 GHz, 130 GHz and 168 GHz each using a custom-designed beam-lead noise diode from M-Pulse Microwave Inc. These noise sources measure a high excess noise ratio ...(ENR) of 17 dB, 9.6 dB and 6 dB at 90 GHz, 130 GHz and 168 GHz, respectively and are to be used for internal calibration in the high-frequency millimeter-wave nadir-viewing radiometers, which are expected to provide increased spatial resolution of wet-tropospheric path delay correction for coastal regions and inland water. The noise sources meet the ENR, radiometric stability, mass and size requirements, which enables us to achieve internal calibration for the high-frequency millimeter-wave channels. Furthermore, we have developed a novel approach that utilizes a MMIC LNA as a noise source in the 168 GHz frequency band. Both of these noise sources have demonstrated excellent stability of 0.07% per hour. This translates to <; 0.1K per hour T A stability for cold ocean scene.
70 GHz radiometer front-end and back-end modules for the Low Frequency Instrument of the European Space Agencys Planck Mission were built and tested. The operating principles and the design details ...of the mechanical structures are described along with the key InP MMIC low noise amplifiers and phase switches of the units. The units were tested in specially designed cryogenic vacuum chambers capable of producing the operating conditions required for Planck radiometers, specifically, a physical temperature of 20 K for the front-end modules, 300 K for the back-end modules and 4 K for the reference signal sources. Test results of the low noise amplifiers and phase switches, the front and back-end modules, and the combined results of both modules are discussed. At 70 GHz frequency, the system noise temperature of the front and back end is 28 K; the effective bandwidth 16 GHz, and the 1/f spectrum knee frequency is 38 mHz. The test results indicate state-of-the-art performance at 70 GHz frequency and fulfil the Planck performance requirements.
We present a medium power amplifier covering frequency range from 18 GHz to 40 GHz and two low noise amplifiers for 94 GHz cloud profiling radar. These integrated amplifiers were manufactured using a ...0.15 μm GaAs based metamorphic high electron mobility transistor (MHEMT) technology. We measured in on-wafer tests for the medium power amplifier, a small-signal gain of 22.5 ± 2.5 dB at K-and Ka-bands. The measured 1 dB output compression point is better than t13 dBm at K-band and better than +9.5 dBm at Ka-band using a 2.5 volts supply. The scattering parameters and the noise figures of the low noise amplifiers were measured at W-band and the results are presented. The best measured gain at 94 GHz was 16 dB and the noise figure 5.7 dB using a supply voltage of 25 V and current of 60 mA.
