Volume 2 Issue 4
Authors: René Gagné; Jean Belzile; Claude Thibeault
Abstract: A glitch masking circuit that masks metastability and synchronization problems for arbitrary input signals is presented. The goals are to define the required elements for circuit implementation and implement a circuit able to, physically, implement the constraints to mask metastability sources so that synchronization appears transparent for the designer. Spice simulation results confirm that the glitch masking circuit produces a viable output for all input signals. It can completely mask all the sources of metastability without performance degradation, at the cost of a latency equivalent to the setup time of a downstream memory element.
Keywords: Metastability Masking; Positive Feedback; Minimum Operation Time
Authors: Shoba Krishnan; Kamala Hariharan
Abstract: Wireless systems customarily use LDO for excellent noise performance at the expense of poor power efficiency. Switching regulators using Pulse Width Modulation (PWM) controllers offer better efficiency but have greater magnitude spurs at multiples of the clock frequency. In this paper, a switching regulator that uses a delta sigma (ΔΣ) controller is considered as a substitute to provide both high power efficiency and improved spurious performance. Tradeoffs in selecting the ΔΣ parameters are investigated for several wireless standards such as WIFI, Bluetooth, GSM, W-CDMA, HSPA, LTE and WIMAX. Simulations in 0.5 µm CMOS technology, performed for key parameters such as spurious performance, efficiency and transient response show that the ΔΣ controller having 3rd order and over sampling ratio (OSR) of 32 can meet the stringent spectral conditions of a GSM system by a 10 dB margin. It also has 8% better power efficiency compared to the PWM controller. The performance of using this ΔΣ buck regulator for dynamically changing load applications is also analyzed. It is shown that for a 13% change in output voltage VOUT, the ΔΣ buck regulator can still meet the spurious constraints of the GSM system.
Keywords: Buck Converter; Delta Sigma Controller; PWM Controller; Wireless Applications; Wireless Standards; Noise Performance; Noise Shaping; Transient Performance; Envelope Tracking
Authors: Salima Balghouzal; Jean-Louis Lilien; Mustapha El Adnani
Abstract: Power lines are thermally designed for decades using standards and sometimes advanced simulation tools. They are using conductor temperature as a key factor for clearance determination. But what is conductor temperature when we all know about temperature changes along the line, even inside one span, circumferential temperature gradient and radial gradient inside the conductor, especially with new type of high temperature conductor, none of existing methods are able to give a fully clear picture of temperature action on the multi-span line along its everyday behaviour. Actually sensors are coming on the market of dynamic line rating, using temperature sensors. These sensors themselves are introducing significant local effects. What is actual link between ampacity and a measurable conductor temperature (which one to consider?). This paper will focus on temperature recording owing to smart sensor which is giving access to behaviour of power line span. Laboratory testing heating up HTLS (high temperature low sag) conductor up to 200°C with a smart sensor installed on the conductor is detailed.
Keywords: Conductor Temperature; Conductor Thermal Behavior; Smart Grids; Sensors; Transmission Lines