Showing papers by "Richard Lai published in 2014"

Cryogenic Probing of mm-Wave MMIC LNAs for Large Focal-Plane Arrays in Radio-Astronomy

Abstract: In this paper, we demonstrate non-destructive cryogenic probing of monolithic microwave integrated circuit (MMIC) amplifiers at W-band and discuss the implications for the development of large-format focal plane arrays for radio astronomy. Using a purpose-built cryogenic probe station to measure S-parameters and noise temperature of MMIC low-noise amplifiers (LNAs), an order of magnitude increase in efficiency can be achieved when compared with measurements on individually packaged amplifiers. The amplifiers are tested non-destructively, which enables selection based on cryogenic noise and gain; this is crucial for the development of highly-integrated miniaturized receivers for focal plane arrays, such as those used for the measurement of the cosmic microwave background (CMB) polarization and future arrays aimed at probing the epoch of reionization (EoR).

LNA modules for the WR4 (170–260 GHz) frequency range

Abstract: In this work, we report on developments toward ultra-low noise amplifier modules for the WR4 frequency range, covering 170-260 GHz. The amplifiers in question utilize 35 nm HEMT transistors on a 50 μm thick InP substrate, and were developed at NGC. While recent work in this frequency band has demonstrated the usefulness and advanced technology of utilizing integrated waveguide transitions fabricated on the high dielectric constant MMIC amplifiers themselves, we present evidence here that more standard, cost effective techniques like merging low-loss quartz probes with short wire bonds can provide excellent noise performance, even at these high frequencies. The amplifiers discussed in this paper demonstrate a record 600K noise (4.8 dB) at 220 GHz and 700K (5.2 dB) noise at 240 GHz.

A W-band heterodyne receiver module prototype for focal plane arrays

Abstract: A compact W-band heterodyne receiver module populated with MMIC LNAs designed and fabricated using a 35 nm InP HEMT process, and an IQ mixer designed and fabricated using the UMS Schottky diode process is developed as the prototype for Argus, a 16-pixel focal plane array to be deployed on the 100-meter Robert C. Byrd Green Bank Telescope in West Virginia to study star formation. The module has a WR-10 waveguide input. GPPO connectors are used for the LO input and the I and Q IF outputs. The module is tested at both ambient (300 K) and cryogenic (26 K) temperatures. A minimum receiver noise temperature of 27 K was achieved, with less than 45 K noise and more than 20 dB gain in the 85 GHz to 116 GHz band. The band-averaged noise temperature is 34 K and 249 K for a physical temperature of 26 K and 300 K, respectively. The IQ amplitude and phase balance shows image rejection better than 15 dB over 90 percent of the band with constant current operation of both mixers. Image rejection better than 25 dB is measured when optimized currents are used to drive the I and Q mixers.

A practical implementation of millimeter and submillimeter wave length on-wafer S-parameter calibration

Abstract: We present an approach for two-port on-wafer calibration to establish the test reference planes within the substrate of the device under test for the WR3 (220-325 GHz) and WR5 (140-220 GHz) frequency bands. On-wafer calibration is useful for characterizing elements such as transistors for modeling or for the confirmation of circuit models. There are numerous publications for on-wafer calibrations, this discussion differs in that we will present our on-wafer calibration approach with comparison of measurements and simulations of passive structures and that of a transistor model constructed from lower frequency measurements. We discuss practical considerations for the approach we have utilized for high frequency characterization.

High electron mobility transistor semiconductor device and method for manufacturing the same

Abstract: PROBLEM TO BE SOLVED: To provide a method for forming a semiconductor device, which allows production of the semiconductor device to be suitable for a sub-millimeter wave operation.SOLUTION: In a method for forming a semiconductor device, a photoresist layer is deposited on a semiconductor substrate 100, a window 106 is formed in the photoresist layer by electron beam lithography, a conformal layer is deposited on the photoresist layer and in the window 106, and substantially all of the conformal layer is selectively removed from the photoresist layer 102 and a bottom portion of the window to form dielectric sidewalls in the window 106.