Tunable C Band Coupled-C BPF with Resonators using Active Capacitor and Inductor

In this thesis, a classic second-order coupled-capacitor Chebyshev bandpass filter with resonators using active capacitor and inductor is presented. The low cost and small size of CMOS active components makes the band pass filter (BPF) attractive in fully-integrated CMOS applications. The active capacitor is designed to compensate active inductor\u27s resistance for resistive match in the resonator. Meanwhile, adjusting design parameter of the active component provides BPF tunability in center frequency, pass band and pass band gain. Designed in 1.8V 180 nanometer CMOS process, the BPF has a tuning frequency range of 758-864 MHz, a controllable pass band of 7.1-65.9 MHz, a Q factor of 12-107, a pass band gain of 6.5-18.1dB and a stopband rejection of 38-50 dB

Log-domain electronically-tuneable fully differential high order multi-function filter

This paper presents the synthesis of fully deferential circuit that is capable of performing simultaneous high-pass, low-pass, and band-pass filtering in the log domain. The circuit utilizes modified Seevinck’s integrators in the current mode. The transfer function describing the filter is first presented in the form of a canonical signal flow graph through applying Mason’s gain formula. The resulting signal flow graph consists of summing points and pick-off points associated with current mode integrators within unity-gain negative feedback loops. The summing points and the pick-off points are then synthesized as simple nodes and current mirrors, respectively. A new fully differential current-mode integrator circuit is proposed to realize the integration operation. The proposed integrator uses grounded capacitors with no resistors and can be adjusted to work as either lossless or lossy integrator via tuneable current sources. The gain and the cutoff frequency of the integrator are adjustable via biasing currents. Detailed design and simulation results of an example of a 5th order filter circuit is presented. The proposed circuit can perform simultaneously 5th order low-pass filtering, 5th order high-pass filtering, and 4th order band-pass filtering. The simulation is performed using Pspice with practical Infineon BFP649 BJT model. Simulation results show good matching with the target

Design Of Receiver Lowpass Filter For UWB Application Using 0.18μm Cmos Technology

The design and analysis of a baseband lowpass filter for UWB application in front end receiver is presented in this report. The objective of this project is to design a lowpass filter which operates with voltage 1.80V and has a bandwidth 264.00MHz by using Silterra 0.18um SMCMOS technology. Transconductor-capacitor filter is the filter architecture being chosen to design and analysis the lowpass filter due to its capability to operate in high frequency, but low power and low cost as compared to passive filter. First to fourth order Gm-C Butterworth lowpass filter is designed and their performance is compared to allow effective filter order selection. First order Gm-C Butterworth lowpass filter has bandwidth 264.00MHz and DC gain of -0.25dB. The 1dB compression point of first order filter is 3.68dBm and third order intercepts point (IP3) at 11.69dBm. The power consumption of first order filter is 5.00mW. Second order filter has bandwidth of 264.00Mhz, DC gain of -0.13dB, 1dB compression point at -0.64dBm, IP3 at 6.05dBm and power consumption of 10.01mW. The third order Gm-C filter has bandwidth 264.00MHz, DC gain of -0.38dB, 1dB compression point at -0.077dBm IP3 at 6.61dBm, power consumption of 15.02mW. The forth order Gm-C filter has bandwidth 264.00MHz, DC gain of -0.26dB, 1dB compression point at -1.92dBm IP3 at 4.50dBm, power consumption of 20.02mW. Third order Gm-C Butterworth lowpass filter has been chosen as baseband filter due to its sharper rolloff in transition from passband to stopband than first and second order filter, and has a better linearity than fourth order filter. The third order filter consists of 72 transistors and 3 MIM capacitor. The size of layout of third order Gm-C filter is 294 286 μm× μm . The designed filter will be sent to Silterra for fabrication into chip and furthermore chip characterization and measurement will be carried out to make sure the measurement of real filter chip can match well as closed as to the simulated result of filter design

Wired, wireless and wearable bioinstrumentation for high-precision recording of bioelectrical signals in bidirectional neural interfaces

It is widely accepted by the scientific community that bioelectrical signals, which can be used for the identification of neurophysiological biomarkers indicative of a diseased or pathological state, could direct patient treatment towards more effective therapeutic strategies. However, the design and realisation of an instrument that can precisely record weak bioelectrical signals in the presence of strong interference stemming from a noisy clinical environment is one of the most difficult challenges associated with the strategy of monitoring bioelectrical signals for diagnostic purposes. Moreover, since patients often have to cope with the problem of limited mobility being connected to bulky and mains-powered instruments, there is a growing demand for small-sized, high-performance and ambulatory biopotential acquisition systems in the Intensive Care Unit (ICU) and in High-dependency wards. Furthermore, electrical stimulation of specific target brain regions has been shown to alleviate symptoms of neurological disorders, such as Parkinson’s disease, essential tremor, dystonia, epilepsy etc. In recent years, the traditional practice of continuously stimulating the brain using static stimulation parameters has shifted to the use of disease biomarkers to determine the intensity and timing of stimulation. The main motivation behind closed-loop stimulation is minimization of treatment side effects by providing only the necessary stimulation required within a certain period of time, as determined from a guiding biomarker. Hence, it is clear that high-quality recording of local field potentials (LFPs) or electrocorticographic (ECoG) signals during deep brain stimulation (DBS) is necessary to investigate the instantaneous brain response to stimulation, minimize time delays for closed-loop neurostimulation and maximise the available neural data. To our knowledge, there are no commercial, small, battery-powered, wearable and wireless recording-only instruments that claim the capability of recording ECoG signals, which are of particular importance in closed-loop DBS and epilepsy DBS. In addition, existing recording systems lack the ability to provide artefact-free high-frequency (> 100 Hz) LFP recordings during DBS in real time primarily because of the contamination of the neural signals of interest by the stimulation artefacts. To address the problem of limited mobility often encountered by patients in the clinic and to provide a wide variety of high-precision sensor data to a closed-loop neurostimulation platform, a low-noise (8 nV/√Hz), eight-channel, battery-powered, wearable and wireless multi-instrument (55 × 80 mm2) was designed and developed. The performance of the realised instrument was assessed by conducting both ex vivo and in vivo experiments. The combination of desirable features and capabilities of this instrument, namely its small size (~one business card), its enhanced recording capabilities, its increased processing capabilities, its manufacturability (since it was designed using discrete off-the-shelf components), the wide bandwidth it offers (0.5 – 500 Hz) and the plurality of bioelectrical signals it can precisely record, render it a versatile tool to be utilized in a wide range of applications and environments. Moreover, in order to offer the capability of sensing and stimulating via the same electrode, novel real-time artefact suppression methods that could be used in bidirectional (recording and stimulation) system architectures are proposed and validated. More specifically, a novel, low-noise and versatile analog front-end (AFE), which uses a high-order (8th) analog Chebyshev notch filter to suppress the artefacts originating from the stimulation frequency, is presented. After defining the system requirements for concurrent LFP recording and DBS artefact suppression, the performance of the realised AFE is assessed by conducting both in vitro and in vivo experiments using unipolar and bipolar DBS (monophasic pulses, amplitude ranging from 3 to 6 V peak-to-peak, frequency 140 Hz and pulse width 100 µs). Under both in vitro and in vivo experimental conditions, the proposed AFE provided real-time, low-noise and artefact-free LFP recordings (in the frequency range 0.5 – 250 Hz) during stimulation. Finally, a family of tunable hardware filter designs and a novel method for real-time artefact suppression that enables wide-bandwidth biosignal recordings during stimulation are also presented. This work paves the way for the development of miniaturized research tools for closed-loop neuromodulation that use a wide variety of bioelectrical signals as control signals.Open Acces

The design of active resistors and transductors in a CMOS technology

Merged with duplicate record 10026.1/2618 on 07.20.2017 by CS (TIS)This thesis surveys linearisation techniques for implementing monolithic MOS active resistors and transconductors, and investigates the design of linear tunable resistors and transconductors. Improving linearity and tunability in the presence of non-ideal factors such as bulk modulation, mobility-degradation effects and mismatch of transistors is a principal objective. A family of new non-saturation-mode resistors and two novel saturation-mode transconductors are developed. Where possible, approximate analytical expressions are derived to explain the principles of operation. Performance comparisons of the new structures are made with other well-known circuits and their relative advantages and disadvantages evaluated. Experimental and simulation results are presented which validate the proposed linearisation techniques. It is shown that the proposed family of resistors offers improved linearity whilst the transconductors combine extended tunability with low distortion. Continuous-time filter examples are given to demonstrate the potential of these circuits for application in analogue signal-processing tasks.GEC Plessey Semiconductors, Plymout

Behavioral modeling for sampling receiver and baseband in Software-Defined Radio

Projecte realitzat en col.laboració amb Illinois Institute of TechnologySoftware Defined-Radio (SDR) consists of a wireless communication in which the transmitter and the receiver are controlled by means of software. Its ultimate goal is to provide a single universal radio transceiver capable of multi-mode multi-standard wireless communications. Modeling of the proper circuits and new designs aimed at SDR is necessary for further development and experimentation. It sharpens our understanding of fundamental processes, helps to make decisions and provides a guide for training exercises. Due to the lack of these models two independent and different models have been created based on new proposed designs. Each modeled design belongs to a different layer of abstraction and therefore, the tool used is different as well. The first proposed model consist of a Simulink (Matlab) file which models the discrete-time signal processing used in a Discrete-time receiver for Bluetooth Radio. The results show good performance when processing a signal that has been transmitted through a noisy channel. The signal at each step is visualized to see the individual effect of each building block. The second proposed model narrows down the topic and focuses on a Widely-tunable, Reconfigurable Analog Baseband filter, for which a Verilog-A model, by using Cadence, has been created. The outstanding feature of the filter is that its programmability is based on the duty-cycle of the input control signals. Moreover, Verilog-A modules bring the design really close to the real circuit, allowing the designer to face problems that the real circuit will present and easing the replacement of the building blocks with new ones when desired. The results for this model show a very little error within the passband of the filter that increases when the attenuation introduced for the stopband becomes higher

Tunable Filters and RF MEMS Variable Capacitors with Closed Loop Control

Multi-band and multi-mode radios are becoming prevalent and necessary in order to provide optimal data rates across a network with a diverse and spotty landscape of coverage areas (3G, HSPA, LTE, etc.). As the number of required bands and modes increases, the aggregate cost of discrete RF signal chains justi es the adoption of tunable solutions. Tunable fi lters are one of the pieces crucial to signal chain amalgamation. The main requirements for a tunable fi lter are high unloaded quality factor, wide tuning range, high tuning speed, high linearity, and small size. MEMS technology is the most promising in terms of tuning range, quality factor, linearity and size. In addition, a fi lter that maintains a constant passband bandwidth as the center frequency is tuned is preferred since the analog baseband processing circuitry tends to be tailored for a particular signal bandwidth. In this work, a novel design technique for tunable fi lters with controlled and predictable bandwidth variation is presented. The design technique is presented alongside an analysis and modeling method for predicting the final filter response during design optimization. The method is based on the well known coupling matrix model. In order to demonstrate the design and modeling technique, a novel coupling structure for stripline fi lters is presented that results in substantial improvements in coupling bandwidth variation over an octave tuning range when compared to combline and interdigitated coupled line fi lters. In order for a coupled resonator filter to produce an equal ripple Chebyshev response, each resonator of the fi lter must be tuned to precisely the same resonant frequency. Production tuned fi lters are routinely tuned in the lab and production environments by skilled technicians in order to compensate for manufacturing tolerances. However, integrated tunable filters cannot be tuned by traditional means since they are integrated into systems on circuit boards or inside front end modules. A fixed tuning table for all manufactured modules is inadequate since the required tuning accuracy exceeds the tolerance of the tuning elements. In this work, we develop tuning techniques for the automatic in-circuit tuning of tunable filters using scalar transmission measurement. The scalar transmission based techniques obviate the use of directional couplers. Techniques based on both swept and single frequency scalar transmission measurement are developed. The swept frequency technique, based on the Hilbert transform derived relative groupdelay, tunes both couplings and resonant frequencies while the single frequency technique only tunes the center frequency. High performance filters necessitate high resonator quality factors. Although fi lters are traditionally treated as passive devices, tunable fi lters need to be treated as active devices. Tuning elements invariably introduce non-linearities that limit the useful power handling of the tunable fi lter. RF MEMS devices have been a topic of intense research for many years for their promising characteristics of high quality factor and high power handling. Control and reliability issues have resulted in a shift from continuously tunable devices to discretely switched devices. However, fi lter tuning applications require fine resolution and therefore many bits for digital capacitor banks. An analog/digital hybrid tuning approach would enable the tuning range of a switched capacitor bank to be combined with the tuning resolution of an analog tunable capacitor. In this work, a device-level position control mechanism is proposed for piezoresistive feedback of device capacitance over the device's tuning range. It is shown that piezoresistve position control is ef ective at improving capacitance uncertainty in a CMOS integrated RF MEMS variable capacitor