RF front end design (PA, LNA, controls) contract and consulting. Rapid PCB / hardware design and new product introduction.

Responsibilities:• Interpret customer needs to system requirements• Establish practical block level performance expectations based on modern, available components• Assess component requirements based upon available data to drive system requirements• Utilize simulation and models to derive device performance• Develop application specific system block prototypes to validate performance prior to design-in• Component selection and schematic capture• Layout, fabrication, and assembly• PCBA bring-up and design verification• Performance margin and yield analysis• Customer validation, support, and successful deploymentProjects:• Prometheus-2 spacecraft comms system PCBAsUHF and S-band dual RF receiver front end and low-loss central RF signal routing PCBAs interfacing five separate RF front ends with dual GOMSpace TR600 SDRs• Titania spacecraft RFFEDesigned octave-bandwidth VHF and UHF RF front ends including FCC compliant medium power amplifiers onto compact PCBA• Faraday Phoenix 6U Cubesat MissionDerived system link requirements based upon orbital altitude, spacecraft antenna gain, and ground station equipment capabilitiesDesigned multi-channel integrated L-band RF front end PCBA featuring low noise amplifiers, filtering, output power limiting, dual-band FCC compliant discrete transmit power amplifiers, and RF signal routingDelivered validated PCBA in conformance with satellite system CONOPs on 3.5 month hardware delivery schedule

Myriota 7 3U Cubesat Mission:Designed, validated, and launched multi-channel integrated VHF and UHF RF front end on 1U (10x10cm) cubesat standard form factor PCBADesign features quad channel LNAs with preselect filtering, output power limiting, and dual FCC compliant discrete medium power UHF transmitter front ends

Designed and layed out digital trimming system for analog control circuit in AltiumDesigned semi-automated characterization system for GaN power amplifier linearity vs. quiescent current in MatlabDesigned hardware to accommodate successful bus sharing between modern I2C and legacy bit-banged systems

Designed, prototyped, and characterized GaN power amplifier interface PCB with programmable bias, supply sequencing, and self-test featuresImpedance controlled PCB transition design using HFSS, Mentor Graphics PCB layout, behavioral and model based SPICE simulationTime and frequency domain and performance verification across wide temperature rangeDeveloped test plans and procedures to perform wide dynamic range spectrum measurements with large resolution bandwidth and low noise requirementsHardware characterization with vector IQ signal generators, Keysight PXA with digital communications options, 89600, time-domain pulsed RF signal characterization, designed post-processing routines in MATLABCharacterized hardware and software based DPD solutions for linearity improvement and PAPR reduction

Designed, prototyped, and characterized high-power 3.5GHz-6GHz GaN PA module using hybrid microstrip, chip & wire, and surface mount technology.Designed, prototyped, and characterized 2-18GHz Wilkinson power combiners at 200W.Developed test plans and procedures.Software experience includes HFSS, Ansys Mechanical, AWR Microwave Office, MATLAB, Autocad.Hardware characterization using VNA, spectrum analyzer, RF power meter, signal generators, programmable power supplies, time-domain reflectometry (TDR), and measuring microscope for mechanical verification.Developed new code and leveraged existing test automation software using VISA and GPIB.

Below is a video of the wireless inertia measurement solution that I developed as a System Applications Engineering Co-op with Analog Devices on demonstration at Electronica 2014 in Munich, Germany.Project skills included embedded programming (Arduino), sensor library development (C++), and a PC-based visual display (Processing). The source code for the demo is available at:https://github.com/dtatum7In addition to my main project, I performed ADC characterization and test of discrete front ends including SFDR, SNR, passband flatness, and harmonics across frequency and temperature. I soldered and debugged evaluation boards to meet client requirements and organized automated or semi-automated tests to verify performance.

Assisted students with assignments and test preparation. Topics included transmission lines, E and H fields, Ampere's, Gauss', Faraday's laws, Maxwell's equations, vector analysis, boundary conditions, constitutive relations, capacitance, inductance, and plane wave propagation.Graded student homework assignments and provided feedback to help with their understanding of the material.Prepared lecture for the class in the absence of the professor.

Developed laboratory experiments for a senior level communications lab class to teach pseudorandom number sequences, eye diagrams, additive white Gaussian noise (AWGN) effects.Programmed a LabVIEW interface for a National Instruments / Ettus 2920 software radio to demonstrate multiple modulation schemes and spread spectrum technologies including direct sequence, CDMA, frequency hopping, and OFDM.

Proposed a discrete component Doherty high efficiency C-band power amplifier design.Worked on a tunable X-band band-pass and band-stop RFIC filter design in Jazz SBC18H3 integrated circuit process.

Developed an embedded radio control system.Analyzed frequency hopping, direct sequence, and hybrid spread spectrum protocols.Designed digitally controllable RF power amplification TX and RX bypass paths.Integrated digital and RF components into one assembly.

Assisted students with multi-semester robotics project using 16-bit accumulator architecture on FPGA, optical encoders, and ultrasonic distance sensors.Demonstrated design practices to prototype discrete analog and digital circuits on a breadboard.Instructed and debugged VHDL code for FPGA based digital designs.Instructed students on usage of oscilloscopes, logic analyzers, programmable DMMs, and function generators with both analog and digital applications.

Developed a model to quantitatively analyze production throughput using a centralized database and distributed reporting from industrial PLCs for future model lines.Coded a server side automated auditing system for backups of industrial computers to identify problems with automated weekly backup.Scripted a client side fault timer for internal company production reporting website.

Taught students electronics soldering, assembly, and inspection.Instructed mobile electronics installation class.

Migrated prototype designs into mass production for clients in the telecommunication, energy management, law enforcement, and medical industries.Communicated manufacturing solutions to production staff, management, and clients to increase first pass production yield.Repaired production and warranty electronic assemblies at component level.Maintained and repaired test fixtures for product quality assurance.Recorded data compliant with ISO standards.