Relationship Between Time-constants and 3dB Cutoff of High-Order Damped LTI Systems

This paper deals with linear time-invariant (LTI) systems and examines the link between the 3dB cutoff and time-constants. It shows that the cutoff frequency of a low-pass damped network can be estimated from the reciprocal of a p-norm calculated from the system\u27s time-constants. Furthermore, to achieve good accuracy the p factor must have a fractional value, for example, p=1.7. Two formulas are derived, and their performance evaluated using Monte Carlo simulations which reveal a sub-3% error for most cases

Buffer Interference Architecture

An up to 3× breakdown voltage tristate capable integrated circuit CMOS buffer includes a level shifter circuit and a driver circuit. The driver stage includes a series connected n-channel and p-channel cascode stacks, each including at least three transistors. Dynamic gate biasing is provided for the third n-channel and p-channel cascode transistors to prevent voltage overstress of the cascode transistors. The level shifter circuit includes at least one pseudo N-MOS inverter including an input transistor, a protective cascode stack including at least one n-channel cascode transistor, and a load transistor. The level shifter provides at least one voltage shifted input signal to the driver

Identifying At-Risk Students: How Use of Optional Study Materials and Collection of Graded Work Correlate with Academic Performance

We report on a study designed to identify students at risk by monitoring certain academic behaviors. Two different approaches were implemented. The first one involves monitoring student access of optional homework problems. While this approach was successful in the early identification of students at-risk, optional homework (as opposed to mandatory one) degrades attainment of learning objectives. The second approach relies upon “counting” of uncollected work. Since no grades were posted, the only way for the students to keep track of their performance was to collect their work. Failure to collect graded work, we argue, is indicative of weak motivation, poor class attendance and poor attendance of office hours. In a class of 114 students, 29 students failed to collect at least one major graded work. Twenty-one of them had below-average class ranking and all students with final grades of F and D+ were part of the underperforming group of 21 students. We also studied the motivating impact of rank-performance plots. The impact of these plots was assessed using an anonymous survey. Total of 89 students participated and 78 of them state they have used the plots to determine their ranking. Total of 36 students (47% of 78) report increased efforts; for students ranking in the bottom 1/3 of the class this percentage was close to 60%. The disadvantage of using rank-performance plots as a motivation tool is an increased anxiety

Robust High-pass and Notch Gm - (grounded) C Biquads: How Many Different Topologies Are There?

This paper deals with Gm-C biquadratic filters that use grounded capacitors. We derive all practical HP and notch filter topologies that do not require critical component matching. The aim of this derivation was to discover new architectures. The result of this derivation is quite unexpected: there are only three distinct topologies (one notch and: two high-pass). None of them is particularly new because all reported in the literature biquad circuits are their embodiments

A System Approach to Integrated Power Amplifier Analysis and Design

Numerous power amplifier circuits are described in the literature, which seem to follow many distinct design approaches. While circuit implementations may be quite different indeed, the underlining system-level signaling inside these circuits follows similar conditions dictated by the common design objective for high efficiency. This paper presents a general theory for analyzing and designing power amplifiers, providing an insight on the fundamental factors limiting the performance, irrespective of the implementation circuits or technology

Method for selecting coupling and by-pass capacitors in multi-stage linear circuits

A method for selecting a set of coupling and by-pass capacitors is presented. The approach uses short-circuit time-constant analysis and for a given −3 dB cut-off frequency minimises the total capacitance used. This study offers a derivation of design formulas and shows their use via examples

Experimental Study and Modeling of the g\u3csub\u3em\u3c/sub\u3e-I Dependence of Long-Channel MOSFETs

This paper describes an experimental study and modeling of the current-transconductance dependence of the ALD1106 and ALD1107 arrays. The study tests the hypothesis that the I-g m dependence of these 7.8 μm MOSFETs conforms to the Advanced Compact Model (ACM). Results from performed measurements, however, do not support this expectation. Despite the relatively large length, both ALD1106 and ALD1107 show sufficiently pronounced `short-channel\u27 effects to render the ACM inadequate. As a byproduct of this effort, we confirmed the modified ACM equation. With an m factor of approximately 0.6, it captures the I-g m dependence quite well. The paper also introduces several formulas and procedures for I-g m model extraction and tuning. These are not specific to the ALD transistor family and can be applied to MOSFETs with different physical size and electrical performance

Alumni Grassroots Leadership Enables Sponsored Course Development

This paper presents a lab-centric course development where alumni, employed by an IAB member company, play a pivotal role. Recently the lead author of this paper qualified for a sabbatical leave and the college enthusiastically approved the proposal (a 400-level elective in networked sensors). He considered two class structures: lecture-only and lecture-lab. While lecture-lab is the desired mode of instruction, the development of such a course would take at least 2 quarters. Since extended sabbaticals are only partly funded by the university the creation of a lecture-lab course hinged on the availability of a sponsor. Simultaneously an alumnus, now with one of our IAB member company, approached the Dept. head with the idea of a company-sponsored lab with emphasis on Internet of Things (IoT). His efforts led to financial and hardware support for the lab enabling the new lecture-lab class. Additionally, he arranged for a summer intern for the firmware development (summer of 2017); the intern is a senior in our department. Another alumnus also joined the team and volunteered his time working on the hardware design. Over the summer, the team completed the hardware and gave the instructor three prototypes allowing him to develop the lab part of the class. The course was approved for the spring quarter of 2018 with the interning senior serving as a lab TA through a departmentally financed position. The format of the partnership allowed us to meet the needs of the stakeholders while minimizing bias in course coverage. Specifically, the professor defined a system based on students’ learning outcomes whereas company participants chose the proper system partition, the form-factor of the boards, and the architecture of each board. Several iterations followed with the goal to support the learning outcomes and use parts that best showcase the company products while also accounting for software availability and students’ level of preparation. In that respect, collaborating with former students proved invaluable. We could not meet all needs exclusively with company products, so the lab hardware also includes products of other manufacturers. This illustrates the partners’ understanding and commitment to the educational goals. The lecture part of the class presents an abstracted view of the material covered in the lab with only partial dependence on sponsor’s technology and technical materials. Besides alumni giving, this paper brings into a focus four other aspects of academic-industry collaboration examined in the literature: 1) industry-supported sabbaticals offer professors an opportunity for a professional growth with a long-term benefits to the university [Batson, 2015]; 2) IAB plays an important role in creating vibrant academic-industry collaborations [Davis, 2008]; 3) academic-industry partnership should extend beyond the commercialization and patenting of innovation and incorporate projects with broader social and economic impact [Filippetti, 2017]; 4) collaborative design of instructional materials, a new paradigm, is becoming an important form of academia-industry collaboration [Crepon, 2015]

Student Perception of Lecture Video Use as a Means to Increase Time for in Class Problem Solving Applications

The purpose of this study is to examine student perceptions of lecture video use as a means to increase available time for in class problem solving in a teaching and learning context. A portion of face to face lectures was replaced with prerecorded lecture video whose viewing was assigned for homework. The freed lecture period was used for additional in class problem solving development, without sacrificing the theory and background that is fundamental. In order to assess the effectiveness of the change in format, student perception was assessed through an anonymous online survey. The survey was given at the completion of a course. The data was collected in two electrical engineering courses. The first was a required sophomore level circuits course and the second was a senior technical elective power electronics course. The survey is a tool to both determine the value of the additional face to face problem solving time and the effectiveness of the video lecture as seen by the student. Students will be asked if they enjoyed the class more than a traditional lecture course and also if they feel they were able to perform at a higher level due to the format. They will also be surveyed to determine if full use was made of both the video lecture and the in class problem solving sessions. The responses showed strong student support for the format and students perceived that they were able to learn material more effectively. There was little difference in the proportions of responses from the different courses despite the different level of students and different instructors. Only student perception was measured and actual student performance data was not assessed as a fair control group could not be established without imposing a perceived disadvantage on one group of students. In total there were 90 students surveyed across the two courses

CMOS Current Mirrors With Reduced Input and Output Voltage Requirements

A CMOS current mirror with lower than VDS(sat) input voltage requirement is presented. It is shown that the structure can be modified to provide cascode-type output resistance for output voltages even lower than 2 VDS(sat). The topology of the proposed current mirror allows low distortion operation from a single 1.5V supply, which makes it attractive for low-voltage applications