A Fully-Integrated Quad-Band GSM/GPRS CMOS Power Amplifier

Concentric distributed active transformers (DAT) are used to implement a fully-integrated quad-band power amplifier (PA) in a standard 130 nm CMOS process. The DAT enables the power amplifier to integrate the input and output matching networks on the same silicon die. The PA integrates on-chip closed-loop power control and operates under supply voltages from 2.9 V to 5.5 V in a standard micro-lead-frame package. It shows no oscillations, degradation, or failures for over 2000 hours of operation with a supply of 6 V at 135° under a VSWR of 15:1 at all phase angles and has also been tested for more than 2 million device-hours (with ongoing reliability monitoring) without a single failure under nominal operation conditions. It produces up to +35 dBm of RF power with power-added efficiency of 51%

Transmitter Architectures Based on Near-Field Direct Antenna Modulation

A near-field direct antenna modulation (NFDAM) technique is introduced, where the radiated far-field signal is modulated by time-varying changes in the antenna near-field electromagnetic (EM) boundary conditions. This enables the transmitter to send data in a direction-dependent fashion producing a secure communication link. Near-field direct antenna modulation (NFDAM) can be performed by using either switches or varactors. Two fully-integrated proof-of-concept NFDAM transmitters operating at 60 GHz using switches and varactors are demonstrated in silicon proving the feasibility of this approach

A Scalable 6-to-18 GHz Concurrent Dual-Band Quad-Beam Phased-Array Receiver in CMOS

This paper reports a 6-to-18 GHz integrated phased- array receiver implemented in 130-nm CMOS. The receiver is easily scalable to build a very large-scale phased-array system. It concurrently forms four independent beams at two different frequencies from 6 to 18 GHz. The nominal conversion gain of the receiver ranges from 16 to 24 dB over the entire band while the worst-case cross-band and cross-polarization rejections are achieved 48 dB and 63 dB, respectively. Phase shifting is performed in the LO path by a digital phase rotator with the worst-case RMS phase error and amplitude variation of 0.5° and 0.4 dB, respectively, over the entire band. A four-element phased-array receiver system is implemented based on four receiver chips. The measured array patterns agree well with the theoretical ones with a peak-to-null ratio of over 21.5 dB

RF Electronics: design and simulation

[Extract] The material presented in this book evolved from teaching analogue electronics courses at James Cook University over many years. When I started teaching electronics design, computer simulation tools were non-existent and most of the design optimisation was done by replacing components in hardware. It was a big step forward when EESOF became available in the mid 1980's. The computer simulation tools have progressed enormously since then. Early in my career, I was given the following advice for designing electronic circuits. "Get the circuit to work and then start taking components out. Put back the one that stops the circuit from working." This is a silly statement, since in a proper design removing any component will stop if from working, but it does illustrate the goal of any designer: Design a circuit that will work first time, according to specification. It must do so reliably and at as low a cost as possible. Since labour is expensive, the circuits also should not require any adjustments after manufacture in order that they meet the specifications

Coherent control of NV- centers in diamond in a quantum teaching lab

The room temperature compatibility of the negatively-charged nitrogen-vacancy (NV-) in diamond makes it the ideal quantum system for a university teaching lab. Here, we describe a low-cost experimental setup for coherent control experiments on the electronic spin state of the NV- center. We implement spin-relaxation measurements, optically-detected magnetic resonance, Rabi oscillations, and dynamical decoupling sequences on an ensemble of NV- centers. The relatively short times required to perform each of these experiments (<10 minutes) demonstrate the feasibility of the setup in a teaching lab. Learning outcomes include basic understanding of quantum spin systems, magnetic resonance, the rotating frame, Bloch spheres, and pulse sequence development.Comment: 16 pages, 9 figure

Application of Active Learning in Microwave Circuit Design Courses

Application of active learning in microwave circuit design courses. We have recently expanded our undergraduate labs to include four 20 GHz VNA-s and four high-speed TDR oscilloscopes. They were obtained initially for junior electromagnetics labs but this opens up obvious opportunities for more hands-on approaches to teaching and learning microwave circuit design. We have redesigned our two quarter, senior-level sequence with these goals in mind: a) Emphasize complete design cycle, from paper development, to simulation, to prototype development and testing, followed by more advanced prototyping, testing and redesign. b) De-emphasize face-to-face lecture and emphasize in-class activities and peer interaction c) Provide students with as much immediate or early feedback as possible by utilizing a new classroom interaction system developed by Learning Catalytics. d) Reinforce student learning by having lab and lecture merge into one so that concepts can be immediately put to practice instead of waiting for assigned lab time. This means that as many designs from item a) should be attempted during class time so that instructor can provide immediate feedback. Work by R. Caverly at U. of Villanova has provided the initial impetus and work by K.C. Guptaon conceptual mapping is providing the framework. We will report on the details of lecture and course design, and lessons learned from the initial offering. Significant emphasis was placed on writing and presentation skills but mixed results were obtained. In the future we will provide more opportunity for students to re-write the reports on their activities instead of expecting that they will incorporate feedback into subsequent reports. We have also discovered some significant gaps or misconceptions in how students think about circuits. For example, they do not fully grasp the concept of admittance vs. impedance and why one may prefer to use one over the other. Similarly, basic concepts of impedance transformation took a long time to develop. We attempted to rank order the effectiveness of various components of the course, as judged by the students. Building and testing circuits and their simulations were perceived as most useful by students, as shown in the figure below. Examples of various class activities will be described, some assessment data provided, and plans for future improvements discussed

An Octave-Range, Watt-Level, Fully-Integrated CMOS Switching Power Mixer Array for Linearization and Back-Off-Efficiency Improvement

The power mixer array is presented as a novel power generation approach for non-constant envelope signals. It comprises several power mixer units that are dynamically turned on and off to improve the linearity and back-off efficiency. At the circuit level, the power mixer unit can operate as a switching amplifier to achieve high peak power efficiency. Additional circuit level linearization and back-off efficiency improvement techniques are also proposed. To demonstrate the feasibility of this idea, a fully-integrated octave-range CMOS power mixer array is implemented in a 130 nm CMOS process. It is operational between 1.2 GHz and 2.4 GHz and can generate an output power of +31.3 dBm into an external 50 Ω load with a PAE of 42% and a gain compression of only 0.4 dB at 1.8 GHz. It achieves a PAE of 25%, at an average output power of +26.4 dBm, and an EVM of 4.6% with a non-constant-envelope 16 QAM signal. It can also produce arbitrary signal levels down to -70 dBm of output power with the 16 QAM-modulated signal without any RF gain control circuit

Characterizing lab instructors' self-reported learning goals to inform development of an experimental modeling skills assessment

The ability to develop, use, and refine models of experimental systems is a nationally recognized learning outcome for undergraduate physics lab courses. However, no assessments of students' model-based reasoning exist for upper-division labs. This study is the first step toward development of modeling assessments for optics and electronics labs. In order to identify test objectives that are likely relevant across many institutional contexts, we interviewed 35 lab instructors about the ways they incorporate modeling in their course learning goals and activities. The study design was informed by the Modeling Framework for Experimental Physics. This framework conceptualizes modeling as consisting of multiple subtasks: making measurements, constructing system models, comparing data to predictions, proposing causes for discrepancies, and enacting revisions to models or apparatus. We found that each modeling subtask was identified by multiple instructors as an important learning outcome for their course. Based on these results, we argue that test objectives should include probing students' competence with most modeling subtasks, and test items should be designed to elicit students' justifications for choosing particular modeling pathways. In addition to discussing these and other implications for assessment, we also identify future areas of research related to the role of modeling in optics and electronics labs.Comment: 24 pages, 2 figures, 5 tables; submitted to Phys. Rev. PE