Ultra-Low-Noise W-Band MMIC Detector Modules

A monolithic microwave integrated circuit (MMIC) receiver can be used as a building block for next-generation radio astronomy instruments that are scalable to hundreds or thousands of pixels. W-band (75-110 GHz) low-noise receivers are needed for radio astronomy interferometers and spectrometers, and can be used in missile radar and security imagers. These receivers need to be designed to be mass-producible to increase the sensitivity of the instrument. This innovation is a prototyped single-sideband MMIC receiver that has all the receiver front-end functionality in one small and planar module. The planar module is easy to assemble in volume and does not require tuning of individual receivers. This makes this design low-cost in large volumes

ALMA Band 5 receiver cartridge. Design, performance, and commissioning

We describe the design, performance, and commissioning results for the new ALMA Band 5 receiver channel, 163–211 GHz, which is in the final stage of full deployment and expected to be available for observations in 2018. This manuscript provides the description of the new ALMA Band 5 receiver cartridge and serves as a reference for observers using the ALMA Band 5 receiver for observations. At the time of writing this paper, the ALMA Band 5 Production Consortium consisting of NOVA Instrumentation group, based in Groningen, NL, and GARD in Sweden have produced and delivered to ALMA Observatory over 60 receiver cartridges. All 60 cartridges fulfil the new more stringent specifications for Band 5 and demonstrate excellent noise temperatures, typically below 45 K single sideband (SSB) at 4 K detector physical temperature and below 35 K SSB at 3.5 K (typical for operation at the ALMA Frontend), providing the average sideband rejection better than 15 dB, and the integrated cross-polarization level better than –25 dB. The 70 warm cartridge assemblies, hosting Band 5 local oscillator and DC bias electronics, have been produced and delivered to ALMA by NRAO. The commissioning results confirm the excellent performance of the receivers

A 660-GHz Electronically Tunable Local Oscillator

We present an electronically tunable local oscillator from 630-675 GHz with upcoming extension to 600-720 GHz using a 13.33-16.00 GHz source followed by a x45 multiplier chain. Output power measurements show >30 μW from 630-675 GHz. FTS and receiver noise measurements using this LO are also presented

Ultra-Thin Silicon Chips for Submillimeter-Wave Applications

We present a process for fabricating ultra-thin silicon chips for submillimeter-wave mixing applications using SOI (Silicon On Insulator) wafers. Such chips allow the profile of the mixer substrate to be minimized within the microstrip channel, thereby simplifying RF design considerations and minimizing machining constraints. The chips feature gold beam leads, RF filter structures, and hot-electron bolometers as the non-linear element. We designed a prototype receiver to demonstrate the feasibility of the ultra-thin silicon chip technology. The receiver has a center frequency of 585GHz and accommodates both diffusion-cooled and phonon-cooled hotelectron bolometer mixers fabricated atop an ultra-thin silicon chip. The chip fits within the microstrip channel of a split-block horn antenna. Protruding from the sides and ends of the silicon chip are thick gold beam leads, which provide electrical and thermal contact between the chip and the waveguide block. In addition, the beam leads provide mechanical support to the chip, allowing the chip to be suspended within the middle of the microstrip channel between the two block halves. Ultra-thin silicon chips with beam leads will facilitate the construction of large format spectroscopic imaging arrays. Such arrays would contain an assembly of individual chips, each featuring a single nonlinear mixing element. The chips could be added, removed of replaced without disturbing the rest of the elements within the array. There are myriad potentials for such systems, examples include atmospheric research, astrophysics, and security systems

ALMA Project Book, Chapter 7: LOCAL OSCILLATORS

reference signals derived from a common master oscillator. The LO subsystem also forms part of the array master clock, in cooperation with a computer of the monitor-control subsystem. It does this by providing an interface to an external time scale (currently GPS) and by measuring the difference between external time and array time. Measures of time larger than 48 msec are obtained in the MC system by integration. Further details are given in a later section. Table 1: Specification Summary Item Specification Goal (if different) Frequency Range, 1st LO 1st LO: 27.3 to 938 GHz (see Table 2) 2nd LO: 8-10 and 12-14 GHz Output Power 1st LO: band dependent (see Table 3) 2nd LO: +10dBm ea. to 2 converters. 100 :W Sideband Noise, 1st LO 10 K/:W3K/:W Amplitude Stability, 1st LO .03% <1s; 3% between adjustments .01%; 1% Phase Noise (>1 Hz) 63 fsec (18.9 :m) 31.4 fsec (9.4 :m) Phase Drift (<1 Hz) 29.2 fsec (8.8 :m) 6.9 fsec (2.1 :m) Tuning step size, maximum On the sky: 250 MHz SIS mixer 1s

Broken-step Phenomenon in SIS Mixers

In this paper, we discuss a “broken step” phenomenonin an SIS mixer. This phenomena was observed in the production version of the SIS mixers, designed for the 159-211 GHz RF band,being used for the construction of the ALMA Band 5 receiver The broken step typically appears at LO frequencies above 180 GHz and manifests itself as a sharp onset in the DC current at the middle of the quasiparticle step. Correspondingly, this affects the mixer IF response in a way that is similar to the Josephson step but is however of a different nature. Such behaviour affects the SIS mixer dynamic range and complicates the tuning of the 2SB mixer to optimize its performance, for both the receiver noise as well as the sideband rejection. In this paper, we describe results of a few experiments which were performed to understand this undesirable phenomenon