A Comparative Study Between a Micromechanical Cantilever Resonator and MEMS-based Passives for Band-pass Filtering Application

Over the past few years, significant growth has been observed in using MEMS based passive components in the RF microelectronics domain, especially in transceiver components. This is due to some excellent properties of the MEMS devices like low loss, excellent isolation etc. in the microwave frequency domain where the on-chip passives normally tend to become leakier and degrades the transceiver performance. This paper presents a comparative analysis between MEMS-resonator based and MEMS-passives based band-pass filter configurations for RF applications, along with their design, simulation, fabrication and characterization. The filters were designed to have a center frequency of 455 kHz, meant for use as the intermediate frequency (IF) filter in superheterodyne receivers. The filter structures have been fabricated in PolyMUMPs process, a three-polysilicon layer surface micromachining process.Comment: 6 pages, 15 figure

A study to evaluate the adequacy of pelvic lymph node coverage in carcinoma cervix patients in Indian population by conventional four field box technique using computerized tomography simulation based pelvic lymph node contouring

Background: Traditionally pelvic External Beam Radiotherapy is delivered with four field box technique in carcinoma cervix patients. The primary aim of this prospective observational study is to determine the adequacy of pelvic lymph nodal coverage by conventional Four Field Box Technique with the help of pelvic lymph node contouring by CT simulation.Methods: Between January 2013 and August 2015 sixty patients with biopsy proven Carcinoma Cervix were enrolled in this study. Of these fifty-three patients were available for final analysis. CT simulation based Pelvic lymph node contouring was done for each patient. Then two External Beam Radiotherapy plans were generated, one contoured based and the other based on bony landmark based Four Field Box Technique. The number of patients whose contoured lymph nodes lies partly outside the field borders of the bony landmark-based plan and also its extent was determined. D90 of various groups of pelvic lymph nodes obtained from both the plans were compared using ‘paired sample t - test’.Results: It was seen that with Four Field Box Technique there is inadequate coverage of common iliac lymph nodes in 34/53 patients. The difference between the mean D90 of common iliac lymph nodes in two sets of plans was found to be statistically significant.Conclusions: Pelvic field planning should be individualized. CT simulation-based radiotherapy planning should be done for each individual patient to adequately cover the nodal microscopic disease

Delta-Sigma Modulator based Compact Sensor Signal Acquisition Front-end System

The proposed delta-sigma modulator ($\Delta\Sigma$M) based signal acquisition architecture uses a differential difference amplifier (DDA) customized for dual purpose roles, namely as instrumentation amplifier and as integrator of $\Delta\Sigma$M. The DDA also provides balanced high input impedance for signal from sensors. Further, programmable input amplification is obtained by adjustment of $\Delta\Sigma$M feedback voltage. Implementation of other functionalities, such as filtering and digitization have also been incorporated. At circuit level, a difference of transconductance of DDA input pairs has been proposed to reduce the effect of input resistor thermal noise of front-end R-C integrator of the $\Delta\Sigma$M. Besides, chopping has been used for minimizing effect of Flicker noise. The resulting architecture is an aggregation of functions of entire signal acquisition system within the single block of $\Delta\Sigma$M, and is useful for a multitude of dc-to-medium frequency sensing and similar applications that require high precision at reduced size and power. An implementation of this in 0.18-$\mu$m CMOS process has been presented, yielding a simulated peak signal-to-noise ratio of 80 dB and dynamic range of 109dBFS in an input signal band of 1 kHz while consuming 100 $\mu$W of power; with the measured signal-to-noise ratio being lower by about 9 dB.Comment: 13 pages, 16 figure