Robert E. Mihailovich

MEM relay for reconfigurable RF circuits

We describe a microelectromechanical (MEM) relay technology for high-performance reconfigurable RF circuits. This microrelay, fabricated using surface micromachining, is a metal contact relay with electrical isolation between signal and drive lines. This relay provides excellent switching performance over a broad frequency band (insertion loss of 0.1 dB and isolation of 30 dB at 40 GHz), versatility in switch circuit configurations (microstrip and coplanar, shunt and series), and the capability for monolithic integration with high-frequency electronics. In addition, this MEM relay technology has demonstrated yields and lifetimes that are promising for RF circuit implementation.

Low-loss 2- and 4-bit TTD MEMS phase shifters based on SP4T switches

2- and 4-bit microelectromechanical system (MEMS) X- to K/sub u/-band true-time-delay phase shifters with a very low insertion loss are described. The phase shifters are fabricated on 200-/spl mu/m GaAs substrates and the low loss is achieved using MEMS SP4T switches, which reduce the number of switches in the signal path by half when compared to conventional designs with SP2T switches. Measurements indicate an insertion loss of -0.6/spl plusmn/0.3 and -1.2/spl plusmn/0.5 dB at 10 GHz for the 2- and 4-bit designs, respectively. The measured losses agreed very well with Momentum simulations and are the lowest reported to date. The 2-bit phase shifter performed well from dc-18 GHz, with -0.8/spl plusmn/0.3-dB insertion loss at 18 GHz and a return loss of <-10.5 dB over dc-18 GHz.

A Ka-band 3-bit RF MEMS true-time-delay network

A monolithic Ka-band true-time-delay (TTD) switched-line network containing 12 metal-to-metal contact RF microelectromechanical system switches has been successfully fabricated and characterized on a 75-/spl mu/m-thick GaAs substrate. The compact 9.1-mm/sup 2/ TTD network was designed to produce flat delay time over a dc-to-40-GHz bandwidth with full 360/spl deg/ phase control at 45/spl deg/ intervals at 35 GHz. Measurements show a match to within 2% to the designed delay times at 35 GHz for all eight switch states with 2.2-dB average insertion loss over all states. Peak rms phase error is 2.28/spl deg/ and peak rms amplitude error is 0.28 dB from dc to 40 GHz. Return loss better than 15 dB from dc to 40 GHz for all eight states confirms the circuits broad-band operation.

A novel MEMS LTCC switch matrix

A novel planar 4/spl times/4 switch matrix using microelectromechanical system (MEMS) switches and low temperature cofired ceramic (LTCC) substrate is presented for the first time. Together a 9-layer LTCC substrate and 32 MEMS switches are integrated to create a non-blocking 4/spl times/4 switch matrix functionality with excellent RF performance up to 7 GHz. An accurate model for predicting the interconnect circuit and switch matrix RF performance up to 20 GHz is also presented.

A 2-bit miniature X-band MEMS phase shifter

The design and performance of a compact low-loss X-band true-time-delay (TTD) MEMS phase shifter fabricated on 8-mil GaAs substrate is described. A semi-lumped approach using microstrip transmission lines and metal-insulator-metal (MIM) capacitors is employed for the delay lines in order to both reduce circuit size as well as avoid the high insertion loss found in typical miniaturized designs. The 2-bit phase shifter achieved an average insertion loss of -0.70 dB at 9.45 GHz, and an associated phase accuracy of /spl plusmn/1.3/spl deg/. It occupies an area of only 5 mm/sup 2/, which is 44% the area of the smallest known X-band MEMS phase shifter . The phase shifter operates over 6-14 GHz with a return loss of better than -14 dB.

A very-low-loss 2-bit X-band RF MEMS phase shifter

A novel low-loss phase shifter, based on RF MEMS series switches and a single-pole four-throw (SP4T) switch design, is presented. The phase shifter is fabricated on a 200 /spl mu/m-thick GaAs substrate, and occupies less than 12 mm/sup 2/ of space. The measured average insertion loss is -0.55 dB, with a reflection loss of less than -17 dB over the 8-12 GHz frequency range. The 2-bit phase shifter performs well up to 18 GHz with an average loss of only -0.85 dB and a near-perfect linear phase shift from DC-18 GHz. This is the lowest loss MMIC-type phase shifter to-date at 8-18 GHz.

Microelectromechanical system radio frequency switches in a picosatellite mission

Rockwell Science Center (RSC) has designed and implemented a microelectromechanical-system- (MEMS-) based radio frequency switch experiment in a miniature satellite format (picosat) as an initial demonstration of MEMS for space applications. This effort is supported by DARPA-MTO, and the mission was conducted with Aerospace Corporation and Stanford University as partners. MEMS surface-micromachined metal contacting switches were manufactured and used in a simple, yet informative, experiment aboard the miniature satellites to study the device behavior in space, and its feasibility for space applications in general. Communication links between multiple miniature satellites, as well as between the satellites and ground, were also achieved using communications circuits constructed and provided by RSC. Details of both the MEMS and radio communications and networking efforts will be discussed in this paper.

Compact, microchip-based systems for practical applications of ultracold atoms

We present a set of building blocks for constructing and utilizing compact, microchip-based, ultrahigh vacuum (UHV) chambers for the practical deployment of cold- and ultracold-atom systems. We present two examples of chip-compatible approaches for miniaturizing UHV chambers—double-magneto-optical-trap cells and channel cells—as well as compact, free-space optical systems into which these cells can be easily inserted and quickly swapped. We discuss progress in atom chip technology, including miniature through-chip electrical feedthroughs and optical windows for transferring light between the trapping region on the chip and the ambient environment. As an example of the latter, we present some of the first through-chip fluorescence images of a Bose–Einstein condensate. High numerical apertures can be achieved with this technique, allowing for submicron resolution. Whether for optical detection, trapping, or control, such fine resolution will have numerous applications in quantum information, especially for experiments based on ultracold atoms trapped in optical lattices.