Armin Jam

A Non-Contact Waveguide Probe for On-Wafer -Parameter Measurements for Submillimeter-Wave to Terahertz Band

This paper presents a non-contact on-wafer S- parameter measurement method for submillimeter-wave and terahertz frequency range. The proposed method is based on using open-ended waveguide probes along with on-wafer waveguide transitions to measure the S-parameters of waveguide based components and devices. To enable non-contact measurements, an RF choke is designed and machined on the metallic cross section of the probes using electric discharge machining. Additionally, to enhance the accuracy and repeatability of the measurements, a probe aligner is micromachined over the on-wafer transition. In order to validate the measurement concept, a full-band transition operating at J-band (220-325 GHz) is designed and tested. To achieve high accuracy, the fabrication of the on-wafer waveguide and the transition is performed using silicon micromachining. It is shown that the designed back-to-back transition has a return loss of better than 15 dB and an insertion loss of less than 0.2 dB over the entire frequency band. The measurement results of the fabricated transition also show a good agreement with the simulated results.

A novel method for chip integration and packaging for millimeter-wave to terahertz band applications

In this paper a novel chip integration and packaging methodology for millimeter-wave to terahertz band applications is demonstrated. The new method is based on peg and socket connection where the line and pads on the MMIC chip mate the lines and pads on the wafer. The socket is micromachined in the wafer and has the exact dimensions of the active chip (peg) with extended membranes to support the lines and pads on the wafer. The lines on the wafer are then transitioned to waveguide using a recently developed grounded-CPW line to waveguide transition. Metalized micro-cylindrical bumps are fabricated on the pads and lines to enhance contact. In order to validate the performance of the proposed integration methodology a prototype is designed and microfabricated at J-band and excellent measured performance is reported in the desired frequency range (220-260 GHz). The new method is a strong candidate for a standardized integration and packaging technique at MMW to THz frequencies and is expected to find a wide range of applications in this area due to its scalability, low fabrication cost, compact form-factor and superb RF performance.

A sub-millimeterwave micromachined frequency beam-steering antenna array

This paper describes a novel travelling-wave frequency beam-scanning array antenna operating at Y-band. The proposed antenna is composed of over 40 cavity-backed patch arrays as the radiating elements, with a total of 588 patch elements. The array generates a very narrow beam (HPBW of less than 2.5°) at the broadside of the antenna with ±25° steering capability. A prototype of the proposed antenna is fabricated using silicon micromachining with high level of accuracy and low mass and cost. To characterize the micromachined antenna, a novel waveguide-probe near-field measurement setup is proposed and good agreement between the measurement and the full-wave simulation results of the antenna is shown.

A novel frequency beam-steering antenna array at Y-band

In this article, a novel frequency beam-scanning phased array antenna operating at Y-band is presented. The proposed antenna is a travelling-wave antenna, with cavity-backed patch arrays as the radiating elements. The array generates a very narrow beam (less than 2.5°) at the broadside of the antenna with ±25° steering capability. A prototype of the antenna is fabricated using silicon micromachining with high level of accuracy and low mass and cost. Moreover, a novel waveguide-probe near-field measurement setup is introduced and utilized to characterize the radiation characteristics of the micromachined beam-steering antenna and an excellent agreement between the measurement and full-wave simulation results is shown.

A Submillimeter-Wave Near-Field Measurement Setup for On-Wafer Pattern and Gain Characterization of Antennas and Arrays

This paper presents a measurement system for on-wafer characterization of antennas operating in the high millimeter wave (MMW) to sub-MMW bands. Most existing antenna measurement systems at these frequencies require complex custom-made structures, which are costly and hard to set up. To address this problem, a simple and yet effective near-field antenna measurement setup consisting of a vector network analyzer (VNA) with proper frequency extenders, a probe station, an on-wafer waveguide probe, and a precision XY-positioner is considered. The waveguide probe attached from one end to a frequency extender of VNA is used to feed the micromachined waveguide port of an on-wafer antenna. A second waveguide probe, connected to the other frequency extender of VNA, is moved over the antenna in the near-field region using the precision XY-positioner. The absolute gain measurement is accomplished by measuring and comparing the near field of a standard gain horn antenna against that of the antenna under test. To validate the performance of the setup, radiation characteristics of a beam-steering traveling wave array antenna and a standard pyramidal horn antenna are measured over 220–325 GHz band and good agreement between the measured and simulated radiation patterns and gains is shown.

A horizontally polarized beam-steerable antenna for sub-millimeter-wave polarimetrie imaging and collision avoidance radars

This paper presents the design, fabrication and evaluation of a novel horizontally-polarized frequency scanning large phased array antenna with high gain and very small form-factor. This antenna is intended for integration with a dual-polarized sub-millimeterwave radar for imaging and navigation applications. The concept is based on a travelling-wave structure composed of 440 cavity-backed patch antenna elements. The array generates a very narrow beam (~2.5° HPBW) with ±25° steering capability. A prototype of the waveguide-fed slot-coupled patch array antenna is fabricated at 240 GHz using multi-layer silicon micromachining and is characterized using a near-field measurement setup at Y-band (i.e. 220-325 GHz). Measurement results, radiation pattern, HPBW, scan range, and gain, agree extremely well the design parameters. A minimum gain of 27 dBi over the desired scan range, and HPBW of less than 3° and 10° in azimuth and elevation planes, respectively, are measured.

Microfabricaion and measurement of a sub-millimeterwave beam-scanning antenna array at Y-band

This paper presents the concept, design and fabrication of beam-scanning array antenna operating at Y-band (230-245 GHz) for light-weight collision avoidance applications. The array consists of over 40 radiating sub-arrays, generating a very narrow beam of less than 3° in azimuth and about 10° in elevation with ±25° azimuth steering capability. Slot-coupled cavity-backed patch arrays are used as the radiating elements of the main antenna in order to confine the beam of the antenna in the elevation plane. Silicon micromaching technology is used to microfabricate the prototype of the antenna. To characterize the micromachined antenna, a waveguide-probe near-field measurement setup is utilized. In the approach an open-ended waveguide probe is used along with on-wafer waveguide transitions to effectively feed the antenna. Measurement results are in excellent agreement with the full-wave simulation results of the antenna.

A micromachined packaging with incorporated RF-choke for integration of active chips at submillimeter-wave frequencies

This paper presents the design, fabrication and evaluation of a novel packaging method for integration of active MMIC at millimeter-wave (MMW) and sub-MMW frequencies. This packaging approach is intended for integration with a micromachined sub-MMW radar system operating at 240 GHz. The concept is based on a peg and socket structure composed of RF transitions and biasing circuitry where the RF and DC pads on the MMIC chip mate with the on-wafer RF transitions and biasing pads, respectively, for a seamless packaging method. To prevent instability of the packaged active device, an ultrawideband RF-choke is devised to provide better than 15 dB of RF isolation between the chip and the biasing circuitry from 30 GHz to 330 GHz. A prototype of the RF-choke along with the rest of the packaging block is fabricated using multi-layer silicon mi-cromachining technology at Y-band (i.e. 220–325 GHz) and the performance is measured where close agreement of the measured and simulated results is shown. Additionally, the proposed integration method is used for packaging of an amplifier at 210 GHz where excellent RF and biasing results are achieved.

Ridge waveguide probe for estimation of the scattering parameters of a device at millimeter- and sub-millimeter-wave frequencies

In this study, we investigate a novel approach for on-wafer testing of active and passive circuits at Y-band and higher. This represents an alternative approach to the conventional coaxial- or CPW-based probes used at lower frequencies. The measurements based on coaxial probes at these high frequencies are unreliable and non-repeatable due to the small size of the fragile probe tips. The small dimensions of coaxial probes are needed to avoid over-moding and radiation from the fingertips of the probe. However, at high MMW and sub-MMW frequencies manufacturing tolerances limits the minimum size of such coaxial probes which inevitably leads to unreliable mode conversion and probe radiation. Another limitation in utilization of coaxial probes is that the smooth physical connection of the probes with on-wafer lines is very hard to achieve due to the small dimensions of the probes and the lines. Besides, the probe tips tend to deform after a number of measurements resulting in unreliable measurements.