Yumin Lu

A MEMS reconfigurable matching network for a class AB amplifier

This letter presents the design of a reconfigurable amplifier with an adaptive matching network implemented by shunt MEMS switches. In particular, the MEMS switches are used as capacitive stubs in double-stub matching circuit designs. The effective capacitance of the switches can be varied by switch activation which results in a change of the matching configuration. The RF response of the adaptive matching network is studied and the power performance of the amplifier is presented.

High-power MEMS varactors and impedance tuners for millimeter-wave applications

A high-power contactless RF microelectromechanical system (MEMS) varactor and an impedance tuner that utilizes this varactor and is simultaneously optimized for maximum impedance coverage and power handling are presented in this paper. The proposed varactor can successfully handle 4 W of RF power (hot tuning) for more than 10/sup 8/ cycles when tested with no hermetic packaging or nitrogen protection. This is the highest power handling under hot tuning conditions reported to date. In addition to this MEMS device, a 30-GHz four-varactor impedance tuner optimized for high-power operation is demonstrated. The power handling capability of this tuner is 4.5 times higher than conventional designs. These results experimentally demonstrate for the first time the significant advantages of contactless MEMS devices over contact-based structures (e.g., switches) for high-power applications.

A fully integrated 24 GHz SiGe receiver chip in a low-cost QFN plastic package

A fully integrated, plastic packaged, 24 GHz SiGe receiver chip is presented. The chip has been manufactured using a commercially available SiGe foundry process. It can be used in a variety of applications including automotive radar sensors and phased-array receivers. The receiver supports two channels which can be used to support sum and delta antenna pattern inputs. The receiver comprises of two LNAs, a DPST switch, an I/Q downconverter, baseband variable gain amplifiers, and integrate-and-dump filters. The receiver has 45 dB of conversion gain with 7.8 dB noise figure (with plastic package) at 24 GHz

A novel MEMS impedance tuner simultaneously optimized for maximum impedance range and power handling

This paper introduces a novel design technique for developing microwave MEMS impedance tuners. Unlike existing designs we simultaneously optimize both the impedance coverage and power handling of the tuner. This allows the tuner to be used in real-life load-pull systems where power handling is equally important to impedance tuning. We further increase the power handling by utilizing contact-less MEMS varactors that can reliably handle more than 3.5 W of power. These principles are demonstrated with a 30 GHz tuner that exhibits very wide impedance tuning and an improvement of 4.5 times (compared to conventional MEMS designs) in terms of the power it can deliver.

Si Based UWB Radar Sensors

Automotive short-range sensor networks at 24 GHz represent the first truly high volume commercial system at mm-wave, with first year production quantities already eclipsing previous products such as autonomous cruise control (ACC), and the various microwave radio networks (e.g. LMDS). The emphasis on product quality, reliability, cost, and performance demanded by automotive OEMs has meant that an innovative approach to product development, packaging, and test has had to be introduced to mm-wave products. This paper will highlight some of the key technical hurdles and their solutions in the development and introduction to production of a 24 GHz UWB radar sensor based on custom-designed SiGe ICs.

A Closed-Loop Pulsed Power Control Circuit for UWB 24 GHz Automotive Radar Transmitter

This paper presents a closed-loop power control circuit for a UWB pulse radar transmitter. It provides over 10 dB of dynamic power control on a 24 GHz pulsed signal with pulse width of 1.59 nS and duty cycle of 0.5%. The circuit consists of an on-board directional coupler, a three-stage power detector and an error amplifier. All the circuits are integrated on the same chip with the transmitter in a SiGe HBT process. Temperature compensation schemes are applied to improve the circuits temperature stability. The circuit consumes 2.7 mA current and occupies only 360 times 480 mum2

RF performance of passive components on state-of-art trap rich silicon-on-insulator substrates

Trap rich silicon-on-insulator (TR-SOI) substrates have been widely adopted for high performance RFICs in cellular front-ends over the past few years. With the more stringent loss and harmonic requirements for 4G and even 5G networks, TR-SOI substrates quality has been improved continuously since its introduction. Two representative types of commercially available TR-SOI substrates are investigated in this paper to demonstrate both small and large signal performance up to 10 GHz. 50 Ohm CPW lines and spiral inductors were fabricated on HR-SOI, TR-SOI, and quartz substrates. The experiment results show that TR-SOI substrates present attenuation coefficient less than 0.2 dB/mm, which is close to that of quartz substrates, and much improved harmonic suppression than HR-SOI substrates.