Eduard F. Stikvoort

Some remarks on the stability and performance of the noise shaper or sigma-delta modulator

The stability constraints of the noise shaper are examined for the purpose of coder design. The author shows that the presence of a limiter in the noise shaper strongly influences the stability criteria on the loop filter of a third- or higher-order coder. A third-order coder was designed according to these results for high-fidelity audio. It performs with a dynamic range of over 100 dB, and the measured in-band noise agrees fairly well with the calculated value. The proposed design procedure also applies to the (sigma-) delta modulator, which is in essence the same device. >

Low power 12-bit SAR ADC for autonomous wireless sensors network interface

Design strategies for power effective and high resolution Successive-Approximation ADCs for autonomous multi-sensor systems are discussed. Specifically, an optimisation for lowest possible power consumption of comparators is addressed and evaluated using both simulations and measurements of a fabricated Si test-chip. The proposed design solution is capable to provide a 12-bit resolution at 50-kHz with only 0.1uW power consumption on a 1.2-V supply. The achieved Figure-of-Merit is 165 ƒJ/convertion-step is, to our knowledge, the best ever reported. The complete ADC area is 0.35 mm2 in NXP 0.14um CMOS technology with only three metal layers.

Polyphase filter section with opamps

An RC active polyphase filter section is presented. The section uses three conventional operational amplifiers (opamps). The transfer function has a single pole and optionally a single zero. With a cascade of these sections, any polyphase filter function can be realized. The paper deals with the leakage caused by element deviation and the effects of a limited gain and gain-bandwidth product of the amplifiers.

Highly linear, varactor-less, 24GHz IQ oscillator

This paper presents a varactor-less, quadrature oscillator with high linearity. It is based on two identical sections comprising a differential Colpitts part and a coupling part. Tuning of the common-mode current and/or differentially changing the tail currents of the coupling and Colpitts parts can achieve the variation of the oscillation frequency. The oscillation frequency can be changed from 23 GHz to 24.4 GHz (10%) for a variation in bias current from 1 mA to 2.25 mA. The linearity in the whole tuning range is better than /spl plusmn/1.5%. The measured phase-noise @1 MHz is about -94 dBc/Hz. At a nominal supply voltage of 3.3 V/spl plusmn/10%, the supply pushing is better than 250 MHz/V. The IQ VCO has been realized in a BiCMOS process (QUBIC4) with 38 GHz f/sub T/ and 3 /spl mu/m thick top metal layer for inductors. The occupied area is 0.23 mm/sup 2/ and the power consumption is 22 mW. Possible applications for this oscillator are IQ downconverters, transceivers for mm-wave and FMCW radar sensors where the linearity of the VCO is an important design specification.

Low Power High-Resolution Smart Temperature Sensor for Autonomous Multi-Sensor System

A low power temperature sensor followed by a switched capacitor amplifier, a buffer stage, and a 12-bit successive approximation analogue-to-digital converter (ADC) for autonomous multi-sensor systems is presented. The proposed design is accurate within 0.01°C from -55°C to 125°C . A proportional to absolute temperature source was used as a temperature sensor. The read-out enables a differential reading of a reference and actual temperature. The subsequent ADC digitizes the output signal. The ADC has a figure-of-merit of 66 fJ/conversion-step at a bit-clock of 50 kHz. The system is implemented in an NXP CMOS 0.14-μm technology. The die area is 0.27 mm2, and the whole system consumes less than 16 μW. Design and measurements are presented.

The CD System as Standardized by Philips and Sony

It should be stressed that this introduction does not intend to mention and recognize all people within Philips and Sony who contributed to establish the CD digital audio system standard in 1980. This standard is based on the collaborative work of many persons, both from Philips and from Sony, and it would be impossible to properly acknowledge all these individuals in the space of only a few pages. More information on the persons involved can be found in the doctoral thesis (in German) by Jurgen Lang (“Das Compact Disc Digital Audio System”, 1996, RWTH, Aachen, ISBN 3-00-001052-1) introduction only aims at describing some important decisions that were made between the successful demonstration of the CD prototype on March 8, 1979, and the establishment of the Philips-Sony CD standard in June 1980.

An accurate RF 0°/180° phase splitter

In most receivers a balanced mixer is used, while the output of the LNA is single ended. The presented phase splitter generates an accurately balanced signal out of a single-ended source. The wide-band circuit consists of two RF transistors and a DC control loop. The circuit operates up to, say, ƒT/4. In the article the basic circuit is discussed and an IC implementation is given.