Quadrature Frequency Synthesis for Wideband Wireless Transceivers

University of Minnesota Ph.D. dissertation. May 2014. Major: Electrical Engineering. Advisor: Ramesh Harjani. 1 computer file (PDF); xi, 112 pages.In this thesis, three different techniques pertinent to quadrature LO generation in high data rate and wideband RF transceivers are presented. Prototype designs are made to verify the performance of the proposed techniques, in three different technologies: IBM 130nm CMOS process, TSMC 65nm CMOS process and IBM 32nm SOI process. The three prototype designs also cover three different frequency bands, ranging from 5GHz to 74GHz. First, an LO generation scheme for a 21 GHz center-frequency, 4-GHz instantaneous bandwidth channelized receiver is presented. A single 1.33 GHz reference source is used to simultaneously generate 20 GHz and 22 GHz LOs with quadrature outputs. Injection locking is used instead of conventional PLL techniques allowing low-power quadrature generation. A harmonic-rich signal, containing both even and odd harmonics of the input reference signal, is generated using a digital pulse slimmer. Two ILO chains are used to lock on to the 10th and 11th harmonics of the reference signal generating the 20 GHz and the 22 GHz quadrature LOs respectively. The prototype design is implemented in IBM's 130 nm CMOS process, draws 110 mA from a 1.2 V supply and occupies an active area of 1.8 square-mm. Next, a wide-tuning range QVCO with a novel complimentary-coupling technique is presented. By using PMOS transistors for coupling two VCOs with NMOS gm-cells, it is shown that significant phase-noise improvement (7-9 dB) can be achieved over the traditional NMOS coupling. This breaks the trade-off between quadrature accuracy and phase-noise, allowing reasonable accuracy without a significant phase-noise hit. The proposed technique is frequency-insensitive, allowing robust coupling over a wide tuning range. A prototype design is done in TSMC 65nm process, with 4-bits of discrete tuning spanning the frequency range 4.6-7.8 GHz (52% FTR) while achieving a minimum FOM of 181.4dBc/Hz and a minimum FOMT of 196dBc/Hz. Finally, a wide tuning-range millimeter wave QVCO is presented that employs a modified transformer-based super-harmonic coupling technique. Using the proposed technique, together with custom-designed inductors and metal capacitors, a prototype is designed in IBM 32nm SOI technology with 6-bits of discrete tuning using switched capacitors. Full EM-extracted simulations show a tuning range of 53.84GHz to 73.59GHz, with an FOM of 173 dBc/Hz and an FOMT of 183 dBc/Hz. With 19.75GHz of tuning range around a 63.7GHz center frequency, the simulated FTR is 31%, surpassing all similar designs in the same band. A slight modification in the tank inductors would enable the QVCO to be employed in multiple mm-Wave bands (57-66 GHz communication band, 71-76 GHz E-band, and 76-77 GHz radar band)

Potentiometric determination of oxybutynin hydrochloride in pharmaceutical formulations at modified carbon paste electrodes

A new potentiometric sensitive and selective modified carbon paste (MCPE) electrodes based on phosphotungestic acid (PTA),  sodium tetraphenyl borate (NaTPB),  phosphomolybdic acid (PMA) or ammonium reineckate (RN) ion pairing agents for determination of (Ox.HCl) were developed. The proposed electrodes have a Nernstian slope values of 58.50±0.71, 58.71±1.20, 54.80±1.30 and 59.20±0.70 mV decade-1for electrodes modified with 20, 10, 5 and 10 mg of Ox-TPB (electrode I), Ox-RN (electrode II), Ox-PMA (electrode III) and Ox-PTA (electrode IV) ion pairs, respectively, with a dynamic drug concentration range at 25 (C was 1.0x10-5 - 1.0x10-2 mole L-1 with detection limit of 1.0× 10-5 mol L-1. The response of MCPEs were pH independent in the range 2.0-6.0 with a fast response time of 10 s for electrode I and 12 s for electrodes II-IV. The MCPEs showed a relatively long life time of 36 days. A pure and pharmaceutical formulation of Ox.HCl was quantified using calibration and standard addition methods and the obtained results agreed with that of the official HPLC method. Validation parameters were optimized according to ICH recommendations.

Quadrature frequency generation for wideband wireless applications

This book describes design techniques for wideband quadrature LO generation for software defined radio transceivers, with frequencies spanning 4GHz to around 80GHz. The authors discuss several techniques that can be used to reduce the cost and/or power consumption of one of the key components of the RF front-end, the quadrature local oscillator.  The discussion includes simple and useful insights into quadrature VCOs, along with numerous examples of practical techniques. ·         Provides a thorough survey of  quadrature LO generation; ·         Offers an intuitive explanation of the different quadrature VCO architectures, and categorization of these architectures based on the intuitive explanations; ·         Describes a new technique for simultaneous quadrature LO generation for channelized receivers; ·         Includes simple and detailed explanation of two new quadrature VCO techniques that improve phase-noise performance of QVCOs, while providing a large tuning range