Broadband equivalent circuit derivation for multi-port circuits based on eigen-state formulation

In this paper a passive guaranteed wide-band equivalent circuit derivation methodology, attempting to bridge physical geometry considerations with equivalent circuits model extractions, is proposed. Electromagnetic (EM) eigen-states formulation is introduced to bridge between physical topology (geometry) and equivalent network architectures. Instead of casting global Z or Y parameters in pole-residue expansions following or T-networks, the proposed methodology considers eigen-states input impedances/admittances as primary goal functions to derive in canonical equivalent circuit models. While classical or T representations are based on global ground assumptions, the proposed methodology refers to local ground references. The validity of the broadband extraction methodology is demonstrated through correlations with RF measurement carried out on CPW transmission lines and coupled RF inductors up to very high frequencies

Modeling of Spiral Inductors

Non

Boundary-integral method for poloidal axisymmetric AC magnetic fields

This paper presents a boundary-integral equation (BIE) method for the calculation of poloidal axisymmetric magnetic fields applicable in a wide range of ac frequencies. The method is based on the vector potential formulation and it uses the Green's functions of Laplace and Helmholtz equations for the exterior and interior of conductors, respectively. The work is particularly focused on a calculation of axisymmetric Green's function for the Helmholtz equation which is both simpler and more accurate compared to previous approaches. Three different approaches are used for calculation of the Green's function depending on the parameter range. For low and high dimensionless ac frequencies we use a power series expansion in terms of elliptical integrals and an asymptotic series in terms of modified Bessel functions of second kind, respectively. For the intermediate frequency range, Gauss-Chebyshev-Lobatto quadratures are used. The method is verified by comparing with the analytical solution for a sphere in a uniform external ac field. The application of the method is demonstrated for a composite model inductor containing an external secondary circuit.Comment: 8 pages, 4 figure

CIRCUIT MODULES FOR SIX-PORT REFLECTOMETER ON CHIP

Broadband signal generator is an indispensable module for broadband Six-Port Reflectometer (SPR). To integrate a whole SPR system on a chip, the source must be compact. In this thesis, a three-stage voltage-controlled oscillator (VCO), using two parallel weak invertor-chain oscillators and sense amplifiers, is proposed and designed in a 0.13 µm CMOS process. These two parallel weak inverter-chain oscillators extend the low frequency operating range and the sense amplifiers expand the high frequency operation. The measurement results show that the oscillator can be tuned from 430 MHz to 12 GHz, which satisfies the targeted SPR operating frequency range. In order to expand the operating frequency band of the SPR, an introduction of the tuning mechanisms is necessary. Inductors and capacitors are the two basic components for the circuit modules of an SPR. Varactors are provided by process vendors. In this thesis, a novel differential active inductor is proposed and implemented in a 0.13 µm CMOS process. The measured self-resonance frequency is 6 GHz, which is the highest self-resonance frequency published thus far for a differential inductor. The proposed structure is further improved by adding a symmetrical negative resistor. Post layout shows a 10 GHz self-resonance frequency. A power divider is a common module in the SPR and microwave circuits. A new lumped-element power divider structure, which presents the strongest tolerance to parasitic resistors in capacitors and inductors, is proposed and analyzed in this thesis by even- and odd-mode method. Varactors and the above-mentioned active inductors are used to build the proposed power divider. The circuit is designed in 0.13 µm CMOS technology with a core area of 300 µm_265 µm. Post layout simulation yields a tuning range from 1 GHz to 7.5 GHz

A review and modern approach to LC ladder synthesis

Ultra low power circuits require robust and reliable operation despite the unavoidable use of low currents and the weak inversion transistor operation region. For analogue domain filtering doubly terminated LC ladder based filter topologies are thus highly desirable as they have very low sensitivities to component values: non-exact component values have a minimal effect on the realised transfer function. However, not all transfer functions are suitable for implementation via a LC ladder prototype, and even when the transfer function is suitable the synthesis procedure is not trivial. The modern circuit designer can thus benefit from an updated treatment of this synthesis procedure. This paper presents a methodology for the design of doubly terminated LC ladder structures making use of the symbolic maths engines in programs such as MATLAB and MAPLE. The methodology is explained through the detailed synthesis of an example 7th order bandpass filter transfer function for use in electroencephalogram (EEG) analysis. © 2012 by the authors; licensee MDPI, Basel, Switzerland.Published versio

Multi-transit Echo Suppression for Passive Wireless Surface Acoustic Wave Sensors Using 3rd Harmonic Unidirectional Transducers and Walsh-Hadamard-like Reflectors

A passive wireless surface acoustic wave sensor of a delay-line type is composed of an antenna, a transducer that converts the EM signal into a surface acoustic wave, and a set of acoustic reflectors that reflect the incoming signal back out through the antenna. A cavity forms between the transducer and the reflectors, trapping energy and causing multiple unwanted echoes. The work in this dissertation aims to reduce the unwanted echoes so that only the main transit signal is left--the signal of interest with sensor information. The contributions of this dissertation include reflective delay-line device response in the form of an infinite impulse response (IIR) filter. This may be used in the future to subtract out unwanted echoes via post-processing. However, this dissertation will use a physical approach to echo suppression by using a unidirectional transducer. Thus a unidirectional transducer is used and also optimized for 3rd harmonic operation. Both the directionality and the coupling of the 3rd harmonic optimized SPUDT are improved over a standard electrode width controlled (EWC) SPUDT. New type of reflectors for the reflective delay-line device are also presented. These use BPSK type coding, similar to that of the Walsh-Hadamard codes. Two types are presented, variable reflectivity and variable chip-lengths. The COM model is used to simulate devices and compare the predicted echo suppression level to that of fabricated devices. Finally, a device is mounted on a tunable antenna and the echo is suppressed on a wireless operating device