Multistandard Analogue Baseband Filters for Software-Defined and Cognitive Radio Receivers

Analogue baseband filters are an important circuit for channel select and anti-aliasing in wireless and mobile communication systems. For software and cognitive radio, they must be widely tunable and reconfigurable to accommodate existing, emerging, and future wireless and mobile standards. In this paper, design considerations of tunable and programmable filters for highly integrated multistandard receivers are presented. General background of multistandard integrated receivers and design challenges of analogue baseband filters are given. Circuit techniques for baseband filter design including the widely used active-RC and Gm-C circuits are described. Filter structures and design methods for high-order baseband filters are reviewed. On-chip tuning issues and methods are discussed. Results and performances of some published design examples are summarized. Future directions are also pointed out.     

Design of high-order active filters in integrated circuits

This correspondence considers the design of high-order filters using follow-the-leader feedback configurations and active-R biquadratic blocks. Statistical sensitivities of various second-order active-R and active-RC sections are compared, and experimental results of a sixth-order Butterworth bandpass filter are also included. The FLF configuration and versatile active-R blocks are also suitable for fully integrated filters.     

Large signal instability in active-R and a class of compensated active-RC filters

Analysis of the large signal instability in compensated active-RC and active-R filters with high pole-Q and pole-frequency is presented. The instability is produced by an oscillator loop formed by two operational amplifiers (OA's). The condition for and the frequency of oscillations are derived.     

A class of predictive analog filters for sensor signal processingand control instrumentation

A class of analog continuous-time filters is introduced, having predictive properties for specified narrow-band signal models, such as low-order polynomials or sinusoids. Such filters are designed by using model transfer functions designed in the discrete-time domain. Z-to-s-domain mapping is done using the inverse bilinear transformation. The analog filters are implemented with active-RC structures, using the state-variable structure for biquads and a single-op-amp structure for real poles and zeros. The application examples include a filter for zero-crossing detectors, polynomial predictors for sensor signal smoothing, and an optimized sixth-order ramp-tracking filter for anti-aliasing and anti-imaging in digital signal processor (DSP) systems where high selectivity is required     

New conversion methods for realizing nonminimum phase transfer functions

New methods are described for converting second-order active-RC low-pass, high-pass, and bandpass filters to obtain nonminimum phase-transfer characteristics. Some of the realizations obtained are superior to other realizations arrived at using well-known conversion methods. Design equations for each realization are summarized in a table. Experimental results are included.     

Large signal instability in active RC biquadratic filter building blocks

A comprehensive report on the investigation of large signal instability in second-order high-Q active-RC filters is given. The condition for oscillation and formulas for evaluating the frequencies are derived. Among the several filter building blocks considered, the ones, which are unconditionally stable, are indicated.     

Employing R-0.5R networks in ultra-low bio-medical active-RC lowpass filters

Utilizing R-2R ladders in design of active-RC approach promotes IC implementation of low frequency filters and leads to high linear and low power design solution for biomedical applications. However, area of R-2R ladders limits low frequency operation of this approach to few tens of Hz. This range is sufficient for designing 60 Hz powerline notch filter, but biomedical lowpass filers requires much lower pole frequencies. This paper investigates the use of other types of ladders (R-αR) in filter design. It shows that among various R-αR ladders, the R-0.5R ladders provide the most attractive solution for designing lowpass filters with ultra-low pole frequency. It is shown that R-0.5R ladders would require as low as 0.7 % of the area of R-2R ladders for realizing a given pole frequency. A second-order fully differential filter was fabricated in a standard 0.18 µm CMOS process. Experimental results showing cutoff frequency of around 1 Hz are provided.     

General sensitivity formulas for lossless two-ports

Simple first-order sensitivity relations, which give the effects of component-value variations, losses and stray elements in both singly and doubly terminated lossless two-ports, are introduced. They provide a generalisation of some earlier results, and also lead to some new formulas. They are also applicable to active-RC and switched-capacitor filters modelled on doubly terminated lossless ladder two-ports.     

Correlated double sampling technique for continuous-time filters

A correlated double sampling technique, applicable to continuous-time active-RC filters, is proposed. It provides suppression of DC offset and 1/f noise, and performs gain boosting and level shifting for the opamps used. A biquad lowpass filter is described to demonstrate the application of the technique.     

Limitations on input signal level in current-mode active-RC filtersusing CCIIs

The maximum input signal level that does not cause clipping and slew-rate limiting effects is investigated for current-mode active-RC filters involving second generation current conveyors (CCIIs), and a simple formula is derived for the maximum input signal amplitude that does not cause nonlinearities     

Dynamic power optimization of active filters with application to zero-IF receivers

This paper describes the use of dynamic impedance scaling and dynamic biasing to dynamically optimize the power dissipation of filters depending on the inband signal level. Transients due to the dynamical changes inside the filter are prevented thanks to the implementation of appropriate switching algorithms. To illustrate the concept, a fifth-order Chebychev low-pass active-RC filter with 100-kHz cutoff frequency, designed for partial channel selection in a zero-IF GSM receiver, is presented. The filter is fabricated in a standard 0.18-/spl mu/m CMOS process and uses a 1.2-V power supply. It consumes 2.22-mA supply current during the presence of the minimum receivable signal. The power dissipation decreases by a factor of 2 as the desired signal strength increases by 3 dB, until it reaches its minimum possible value of 0.46 mW. There are a total of five power settings in the filter.     

Systematic Synthesis of Active-RC Circuit Building-Blocks

In this paper, we show how some basic building blocks for active-RC circuit design, such as amplifiers, impedance converters and simulated inductance circuits, may be synthesised in a systematic way by expansion of their port admittance matrices. The circuit topology emerges from the synthesis procedure, allowing all possible implementations to be identified and explored. Nullors representing ideal op-amps and transistors are represented within the nodal admittance matrix of a synthesised circuit by linked infinity parameters. In nodal admittance matrices describing ideal circuits synthesised, the replacement of linked infinity parameters by finite parameters provides a seamless transition to non-ideal analysis and practical circuit design.Now with the Singaporean Armed Services.David Haigh was born in Middlesex, England, in 1946. He obtained the B.Sc. degree in Electrical Engineering from Bristol University in 1968 and in 1976 he received the Ph.D. degree from the University of London. From 1968 until 1972 he worked under Dr. Wolja Saraga first at the GEC Hirst Research Centre and then, from 1972, at Imperial College London where he worked on microelectronic high precision filters. In 1987 he joined the staff of the Electronic and Electrical Engineering Department of University College London, where he studied analogue integrated circuit design with particularly interest in high frequency circuits. In 2003 he re-joined the Department of Electrical and Electronic Engineering at Imperial College London, where his interests broadened to include general approaches for analogue circuit synthesis. He is editor-in-chief (Europe) of the Analog Integrated Circuits and Signal Processing Journal.Fang Qun Tan graduated with a B.Eng. degree from Imperial College London in 2002. He then studied for the M.Sc. in Analogue and Digital integrated Circuit Design at Imperial College and graduated with distinction in 2003. His M.Sc. project was on the subject of systematic synthesis methods for analogue circuits. At present Fang Qun is with the Singapore Armed Services.Christos Papavassiliou was born in Athens, Greece, in 1960. He received the B.Sc. degree in physics from the Massachusetts Institute of Technology and the Ph.D. degree in Applied Physics from Yale University. He has worked on monolithic microwave integrated circuit (MMIC) design and measurements at FORTH in Crete, Greece, and has been involved in several European and regional projects on GaAs MMIC technology. In 1996 he joined Imperial College London, where he is currently a Senior Lecturer. He currently works on SiGe technology development as well as instrumentation and substrate noise coupling in mixed mode integrated circuit design. He has 30 publications.     

0.5-V analog circuit techniques and their application in OTA and filter design

We present design techniques that make possible the operation of analog circuits with very low supply voltages, down to 0.5 V. We use operational transconductance amplifier (OTA) and filter design as a vehicle to introduce these techniques. Two OTAs, one with body inputs and the other with gate inputs, are designed. Biasing strategies to maintain common-mode voltages and attain maximum signal swing over process, voltage, and temperature are proposed. Prototype chips were fabricated in a 0.18-/spl mu/m CMOS process using standard 0.5-V V/sub T/ devices. The body-input OTA has a measured 52-dB DC gain, a 2.5-MHz gain-bandwidth, and consumes 110 /spl mu/W. The gate-input OTA has a measured 62-dB DC gain (with automatic gain-enhancement), a 10-MHz gain-bandwidth, and consumes 75 /spl mu/W. Design techniques for active-RC filters are also presented. Weak-inversion MOS varactors are proposed and modeled. These are used along with 0.5-V gate-input OTAs to design a fully integrated, 135-kHz fifth-order elliptic low-pass filter. The prototype chip in a 0.18-/spl mu/m CMOS process with V/sub T/ of 0.5-V also includes an on-chip phase-locked loop for tuning. The 1-mm/sup 2/ chip has a measured dynamic range of 57 dB and draws 2.2 mA from the 0.5-V supply.     

Design of optimum actively compensated networks

This paper describes an active compensation technique which is readily applicable to all active-RC networks, independently of the circuit topology. This procedure considers the network in its totality and derives general active compensation conditions for a generic active-RC network employing 2 or 3 operational amplifiers. Furthermore, the remaining degrees of freedom of the circuits are used to optimize the performance of the actively compensated circuits to further extend its operating frequency range. Simulation and experimental results are also reported.     

微电子技术实验教学平台的构建

通过对以集成电路为核心的微电子技术人才培养的分析和研究,提出了微电子技术实验教学平台的建设规划和内容。针对微电子学专业的特点,微电子技术实验教学平台应包括三个方面:专业基础实验室、半导体工艺实习基地和集成电路设计实践教学平台。通过微电子技术实验教学平台的建设,将可以形成完善的北京工业大学微电子技术实验教学体系。     

A Power Optimized Continuous-Time ∆Σ ADC for Audio Applications

We present design considerations for low-power continuous-time modulators. Circuit design details and measurement results for a 15 bit audio modulator are given. The converter, designed in a 0.18 mum CMOS technology, achieves a dynamic range of 93.5 dB in a 24 kHz bandwidth and dissipates 90 muW from a 1.8 V supply. It features a third-order active-RC loop filter, a very low-power 4-bit flash quantizer, and an efficient excess-delay compensation scheme to reduce power dissipation.     

NOVEL SECOND-ORDER CURRENT MODE FILTERS USING CCIIs

Two new current mode active-RC networks using the second generation current conveyer (CCII) devices are presented. The circuits provide high-Q bandpass (BP)/lowpass(LP) filter characteristics; the highpass(HP) response may also be obtained with suitable design. Current mode sine wave signal generation (Q→α) is possible by tuning a grounded resistor. With non-ideal CCIIs the design equations are slightly altered owing to CCII port current and voltage tracking errors (Ei,v).     

Thin-film distributed RC parameter strain gauges

Thin-film cermet resistance strain gauges provide gauge factors of the order of 15, while providing higher stability than achievable with discontinuous thin-film metallic strain gauges. Strain-sensitive cermet resistors can be incorporated advantageously into thin-film distributed parameter notch filters. This results in a highly sensitive strain-sensing device which can be fabricated by a simple process germain to the thin-film microelectronic technology.     

依托专业特色,培养创新人才

培养创新人才是高校教育的基本方针,加强实践教学建设,是培养创新人才的关键所在。北京工业大学电子科学与技术专业定位于培养微电子器件、集成电路设计和芯片制备工艺等方面的专业技术人才,在实践教学中建设了由集成电路设计实验室(设计)、微电子工艺实习基地(工艺)和专业基础实验室(测试)构成的微电子实践教学体系,另一方面采取多种措施,加强实践教学队伍建设,从而达到了依托专业特色、培养创新人才的目的。