Ali Attaran

60 GHz Low Phase Error Rotman Lens Combined With Wideband Microstrip Antenna Array Using LTCC Technology

This paper presents a new design technique and analysis for a microstrip Rotman lens which is feeding a wide bandwidth series-fed microstrip patch antenna array. In the proposed Rotman lens method, the length of the transmission lines does not affect the progressive phase delay. This reduces the complexity of the design and improves the performance parameters. An antenna array is utilized using open ended λ/4 stubs to support high gain, directivity, and a wide bandwidth. The Rotman lens and antenna arrays are fabricated on the top layer of a multilayer low temperature cofired ceramic substrate. The Rotman lens has been designed based on the presented technique, which has five beam ports, five array ports, four dummy ports, and a footprint as small as 11 mm × 10.7 mm at 60 GHz operation frequency. The implemented lens and antenna array exhibits good insertion loss, return loss, and wide bandwidth and shows phase error as small as 0.45° in the worst case scenario.

Fabrication of a 77 GHz Rotman Lens on a High Resistivity Silicon Wafer Using Lift-Off Process

Fabrication of a high resistivity silicon based microstrip Rotman lens using a lift-off process has been presented. The lens features 3 beam ports, 5 array ports, 16 dummy ports, and beam steering angles of ±10 degrees. The lens was fabricated on a 200 m thick high resistivity silicon wafer and has a footprint area of 19.7 mm × 15.6 mm. The lens was tested as an integral part of a 77 GHz radar where a tunable X band source along with an 8 times multiplier was used as the RF source and the resulting millimeter wave signal centered at 77 GHz was radiated through a lens-antenna combination. A horn antenna with a downconverter harmonic mixer was used to receive the radiated signal and display the received signal in an Advantest R3271A spectrum analyzer. The superimposed transmit and receive signal in the spectrum analyzer showed the proper radar operation confirming the Rotman lens design.

Rotman lens combined with wide bandwidth antenna array for 60 GHz RFID applications

This paper presents a novel technique to design a Rotman lens feeding a wide bandwidth microstrip patch antenna array for 60 GHz radio frequency identification (RFID) applications. The proposed scheme supports both location positioning and increases the communication range through beam forming. The antenna array is designed using λ/4 microstrip transmission lines to support high gain, directivity, and bandwidth. The progressive phase delay using the Rotman lens is realized independently using transmission lines to reduce the complexity of the design and improve the performance parameters. The dummy ports are terminated by λ/4 radial stubs which eliminates the need for via holes and expensive connectors which reduces the fabrication costs.

Test method for capacitive MEMS devices utilizing pierce oscillator

In this paper a test method for MEMS devices is presented in which physical defects are detected in the frequency domain rather than the time domain. A resonator, that can be part of a read out circuit, is utilized to test capacitive Micro-Electro-Mechanical Systems (MEMS). The proposed technique is based on the principle of resonant frequency where variations of the resonant frequency are observed to detect structural defects. To verify the validity of the proposed approach, a MEMS comb-drive is designed and fabricated. Measurement and simulation results indicate that the proposed method can be used to capture common comb-drive defects such as missing or broken fingers, shorted fingers and tilted arms.

An embedded low-overhead PLL-based countermeasure against DPA side channel attack

Side channels attacks are considered among physical, noninvasive methods employed to obtain private key of cryptographic devices such as smart cards. In this paper, a new approach for countermeasure against Differential Power Analysis (DPA) with an extremely low-area and -power overhead is proposed. The proposed method employs a Phase Locked Loop (PLL) which is placed in the power path of an Advanced Encryption Standard (AES) based encryption system. This method suppresses the power characteristic of the encryption system through both masking and hiding the private key information. Moreover, the proposed method is successful in maintaining high frequency operation of the encryption engine. The proposed method is implemented in TSMC CMOS 65nm technology. The protection circuit has only 5% area overhead, and 6% increase in power consumption, with frequency degradation of only 1%.

DLL based test solution for interposers in 2.5-D ICs

Silicon interposer is the enabling technology for 2.5D IC integration which supports higher levels of integration and improved electrical performance. An interposer can suffer from various physical defects affecting the overall performance of 2.5D ICs. This paper presents a new method to perform manufacturing tests for interposers utilizing a Delay Locked Loop (DLL). In the proposed method short-time intervals are first amplified through a time-amplifier and then measured. Simulation results using ADS software with 65 nm TSMC CMOS technology indicates that proposed method can detect minor structural defects affecting the propagation delay of interconnect by more than 1.5ps resolution.

Power harvesting using tuned comb drive

Wireless power transfer has gained considerable interest due to its wide range of applications. The power harvesting systems that extract the power from the electromagnetic waves are tuned to the frequency of the incoming signal. In this work, a mathematical model has been developed for MEMS comb-drive which can be used in power harvesting systems, to estimate its resonant frequency. The effects of different design parameters on the resonant frequency have been studied. Simulation results using Coventerware CAD tools indicate that the mathematical model properly predict the response of the MEMS comb drive for different ratio of finger length and finger pitch. The implemented comb drive was also analyzed for its power scavenging capacity. The result shows 592 μJ available energy for an area of 7mm2. The simulation results also confirm that the desired frequency is attainable with an accuracy in the range of few hertz.

Resonant-based test method for MEMS devices

In this paper a test method for capacitive Micro-Electro-Mechanical Systems (MEMS) is presented. The proposed method utilizes the principle of resonant circuits to detect structural defects of capacitive MEMS devices. It is shown that a small variation of MEMS capacitance due to a defect alters the resonance frequency considerably. It is also shown that the variation of the output amplitude can be observed for fault detection if an inductor with a high quality factor is employed in the test circuit. Simulation results using an implemented MEMS comb-drive indicate that the proposed method can detect common faults such as missing, broken and short fingers.

High performance silicon based Rotman lens for automotive radar applications

Design and fabrication of a silicon based microstrip Rotman lens for use in automotive collision avoidance applications is presented. The lens has 3 beam ports, 5 array ports, 16 dummy ports, and beam steering angles of ±10 degrees. 3-D full wave simulation using XFDTD™ shows better than 8 dB return loss, less than 0.5 degrees beam to array phase error and sidelobes level of less than -12 dB. The lens is fabricated on a 200 μm thick high resistivity silicon wafer. A functional test of the lens is conducted in a 77 GHz radar setup and the test results show that the lens is working fine as designed.