Microwave integrated circuits

This research refers to a proof-of-concept study concerning the development of a
noninvasive blood-glucose monitoring system. The biosensor being considered is a
microwave-based transducer (that can be rendered compatible for ISM band of 2450
MHz and hence Zigbee™ and/or BluetoothTM compliant). The goal of this study is
tailored to develop eventually a unit for home-based healthcare and/or personalized
wellness monitoring of diabetic patients. This pilot effort is expected to culminate in
future in a wireless hyper/hypoglycemic risk-alert system and possible automatic insulin
infusion pump activation efforts.
The thesis addressed thereof provides details on the fundamentals of sensing
glucose content noninvasively across a finger. The underlying principle of biosensing
refers to detecting the change in the dielectric property of blood with differential changes
in the glucose influx in the finger by sensing microwave (such as 2450 MHz) absorption
and/or reflection so as to assay the glucose content of interest. Preliminary experimental
and theoretical results are presented and discussed.

In printed circuits employing high-speed digital circuits, the interconnects can be considered as transmission lines. The dispersion effects in signals transmitted via such interconnects are of importance in crosstalk phenomena inasmuch as the amount of interline coupling (or crosstalk) in a symmetric, coupled microstrip version of interconnect depends on the difference between the frequency-dependent propagation constants pertinent to even and odd modes of lines. This dissertation is concerned with the studies on the distortion and coupling of transient signals propagating in a symmetric, coupled and lossy (dispersive) microstrip transmission lines. Both time as well as frequency domain characteristics are analyzed and relevant mathematical expressions are obtained vis-a-vis pulse signals on signal lines and coupling on sense lines. Fourier transform technique (FT) and spectral domain approach (SDA) are the methods used in the studies pursued. Specifically, an optimization technique to minimize crosstalk in multilayered, multitrace microstrip lines is developed. Typical simulation results are finished which indicate the feasibility of achieving a crosstalk reduction by 76% at a given distance of 40 mm from the source-end excited with a 25 picosecond gaussian pulse by optimization of the geometry of the structure appropriately. This technique is a new strategy for optimal design of high-speed, digital interconnections on a printed circuit board (PCB). The anomalous behavior of the crosstalk versus the pulse-width of a high-speed digital signal in a closely-spaced, parallel coupled microstrip line is presented. It is shown that depending on the pulse-width of a pulse signal, the space between two lines must be beyond a certain limit for a given strip-width (w) and strip-thickness (h) so that crosstalk can be reduced by spacing lines away. The relevant analysis indicates plausible reasons which cause the said anomalous characteristics of crosstalk. A transient signal propagating on a multilayered, coupled microstrip line with lossy substrates is characterized. Relevant computational algorithm is presented. The Cole-Cole diagrams depicting the odd and even mode complex permittivity versus frequency are evolved. The concept of Cole-Cole representation is applied to analyze crosstalk in a microstrip line. Typical simulations show some very interesting and useful results. This study is the first of its kind and has not been done earlier. Lastly, relevant to above research, logical inferences and conclusions are enumerated and the scope for future research is presented.