Juha Häkkinen

Bio: Juha Häkkinen is an academic researcher from University of Oulu. The author has contributed to research in topics: Phase-locked loop & Direct digital synthesizer. The author has an hindex of 9, co-authored 44 publications receiving 328 citations.

A practical /spl Delta/-/spl Sigma/ modulator design method based on periodical behavior analysis

Abstract: A method for digital delta-sigma modulator design for fractional-N frequency synthesis is presented in this paper. The design method is based on the modulator periodical behavior analysis. The modulator is designed to maintain a constant output signal sequence length which can be controlled for all input dc levels. As a result, the quantization noise power is spread over a known, arbitrarily large number of tones within the Nyquist bandwidth. Therefore, the quantization noise power never concentrates into a few dominant spurious tones. The sequence length is controlled by applying predefined initial conditions and scaling modulator buses. Consequently, the spurious-free range can be controlled as a function of the bus width. Known modulator sequence length defines the time required for full modulator and synthesizer characterization.

A practical Δ-Σ modulator design method based on periodical behavior analysis.

Abstract: A method for digital delta-sigma modulator design for fractional- frequency synthesis is presented in this paper. The design method is based on the modulator periodical behavior analysis. The modulator is designed to maintain a constant output signal sequence length which can be controlled for all input dc levels. As a result, the quantization noise power is spread over a known, arbitrarily large number of tones within the Nyquist band- width. Therefore, the quantization noise power never concentrates into a few dominant spurious tones. The sequence length is con- trolled by applying predefined initial conditions and scaling mod- ulator buses. Consequently, the spurious-free range can be con- trolled as a function of the bus width. Known modulator sequence length defines the time required for full modulator and synthesizer characterization. Index Terms—Delta-sigma modulation (DSM), digital circuits, frequency synthesizers, limit cycles, phase noise.

A Robust Algorithm to Identify the Test Stimulus in Histogram-Based A/D Converter Testing

Abstract: Traditional testing of analog-to-digital converters (ADCs) with automatic test equipment is time-consuming and expensive, and a built-in self-test (BIST) can be one solution to this problem. Most of the proposed BIST routines require a well-known test stimulus which is much more linear than the device under test. A stimulus error identification and removal (SEIR) method that does not require a high-linearity stimulus has been proposed recently, and it is evident that reliable test results could be achieved with a stimulus linearity lower than the required measurement accuracy. This paper presents a simple and easy-to-implement calculation algorithm for use with the stimulus-identification method, particularly for BIST purposes. Simulations demonstrate that the integral-nonlinearity measuring accuracy of the SEIR method with the new calculation algorithm is 1 least significant bit for 14-b ADCs, even though the linearity of the test stimulus is only 7 b. The SEIR method and the new simpler calculation algorithm can reduce the hardware resources required for ADC BIST.

All Silk-Screen Printed Polymer-Based Remotely Readable Temperature Sensor

Abstract: In this paper, we present the fabrication and characterization results of a remotely readable flexible temperature sensor. The sensor has been fabricated with screen printing technology and it consists of a polymer-based capacitor (ASAHI CR18-KTI polymer paste) as a temperature sensitive component added to the antenna coil (ASAHI LS411-AW silver paste) for remote reading purposes. The resonance frequency of the sensor (i.e., the formed LC network) is measured as a function of temperature. The sensor has been characterized in the temperature range of 0 °C-70 °C and the total sensitivity over this range is ~9 kHz/°C. The sensor's normalized temperature response is independent from the polymer capacitor's thickness and the effective capacitor area, which enables reasonable performance despite fabrication process induced inaccuracies. Due to the inexact nature of the resonance peak measurement, a dataanalysis algorithm was developed to enhance the accuracy of the measurement method. In addition, the sensor response to the misaligned reader and the sensor self-heating effect, due to the inductive excitation voltage, are considered. Finally, the calibration of such a sensor is discussed.

Bending reliability of printed conductors deposited on plastic foil with various silver pastes

Abstract: The cyclic bending reliability of printed conductors fabricated with different polymer thick film pastes is studied in this article. Three silver pastes with different properties, Asahi SW1400, Asahi LS411AW, and DuPont 5064H, were utilized to deposit test specimens on a 125-μm thick polyethylene terephthalate foil, Melinex ST506, and to investigate the paste characteristics affecting the mechanical durability of the test specimens. The main fabrication method for the traces was roll-to-roll printing with a rotary screen, but also a sheet-based screen printing process was used to compare the results between the two manufacturing techniques. The electrical behavior of the test components was monitored by measuring the DC resistance of the test samples in situ under cyclic bending in both compression and tension with about a 6 mm bending radius. The reliability of the studied test populations was assessed with the statistical Weibull analysis as the failure criterion was a 20 % increase in resistance. It was found that the conductors fabricated with the paste with the smallest silver particle size, Asahi SW1400, had the highest lifetimes. This was due to the more flexible micro-scale structure with a lower volume fraction of silver in the paste. In addition, heat-treatment during the printing process was observed to be a crucial factor from the both electrical and mechanical perspectives of the printed conductors.

UWB theory and applications

Abstract: Introduction. UWB Channel Models. Modulation Schemes. Receiver Structures. Integrated Circuit Topologies. UWB Antennas. Medium Access Control. Positioning.

Beyond the Boundary

Abstract: Preparing the books to read every day is enjoyable for many people. However, there are still many people who also don't like reading. This is a problem. But, when you can support others to start reading, it will be better. One of the books that can be recommended for new readers is beyond a boundary. This book is not kind of difficult book to read. It can be read and understand by the new readers.

The Design of CMOS Radio-Frequency Integrated Circuits: RF CIRCUITS THROUGH THE AGES

Abstract: This expanded and thoroughly revised edition of Thomas H. Lee's acclaimed guide to the design of gigahertz RF integrated circuits features a completely new chapter on the principles of wireless systems. The chapters on low-noise amplifiers, oscillators and phase noise have been significantly expanded as well. The chapter on architectures now contains several examples of complete chip designs that bring together all the various theoretical and practical elements involved in producing a prototype chip. First Edition Hb (1998): 0-521-63061-4 First Edition Pb (1998); 0-521-63922-0

Review of Flexible Temperature Sensing Networks for Wearable Physiological Monitoring

Abstract: Physiological temperature varies temporally and spatially Accurate and real-time detection of localized temperature changes in biological tissues regardless of large deformation is crucial to understand thermal principle of homeostasis, to assess sophisticated health conditions, and further to offer possibilities of building a smart healthcare and medical system Additionally, continuous temperature mapping in flexible and stretchable formats opens up many other potential areas, such as artificially electronic skins and reflection of emotional changes This review exploits a comprehensive investigation onto recent advances in flexible temperature sensors, stretchable sensor networks, and platforms constructed in soft and compliant formats for wearable physiological monitoring The most recent examples of flexible temperature sensors are first discussed regarding to their materials, structures, electrical and mechanical properties; temperature sensing network technologies in new materials and structural designs are then presented based on platforms comprised of multiple physical sensors and stretchable electronics Finally, wearable applications of the sensing network are described, such as detection of human activities, monitoring of health conditions, and emotion-related bodily sensations Conclusions are made with emphasis on critical issues and new trends in the field of wearable temperature sensor network technologies