I Love Power Electronics

Power · RF · Analog — from DC to daylight

Hi. I love power electronics! Here is some of my work.

I'm Sierra, an electrical engineer with 18 years in power electronics, RF/microwave, and analog design. This site is my portfolio of past work and a home for the browser tools I use every day.

Open the tools See past work

Currently: happily building hardware at a Bay Area startup

Tools I use every day

Built for my own work · free · no install, no login

/webrfsim WebRFsim Planar EM simulation for printed RF structures including hairpin and stepped-impedance filters right in your browser. WebRFsim current-density plot of a coupled-line bandpass filter Open tool → /webmagsim WebMagSim 2-D finite-element magnetics in the browser including magnetostatics, eddy currents, and electrostatics. WebMagSim flux plot of a transformer core and windings over its triangular mesh Open tool → /webelectools WebElecTools Everyday design calculators: core flux density, LC and solenoid inductors, capacitor loss, LLC and class-E design, dividers, thermal, and many more. WebElecTools buck converter schematic Open tool →

Areas of expertise

15 years

Switching power supplies

SMPS, PFC and inverter design from 1 W to over 50 kW in pulsed applications. Low-distortion sine synthesis into non-linear loads. Motor drives, VFDs, deadbeat and digital control loops.

10 years

RF & microwave

Design up to 24 GHz. Cascade analysis and receiver design, LNAs, printed antennas and filters, class-E power amplifiers up to 100 W, hybrid PTFE/FR-4 stackups up to 10 layers.

18 years

Analog

Amplifiers, current sources, level shifters and RF detectors. Transimpedance amplifiers for high-speed optical receivers.

10 years

EMC, FCC, UL & CE

Conducted and radiated emissions reduction for industrial and consumer products. Clearance, creepage and product-safety design for certification.

Topologies

  • Resonant
  • LLC
  • PSFB
  • Full bridge
  • Forward
  • Flyback
  • Buck
  • Boost
  • ZVS/ZCS

Control

  • Classical voltage & current mode
  • Hysteretic voltage & current mode
  • Deadbeat current mode
  • PID loops
  • Digital loop compensation
  • DSP control firmware

Magnetics

  • Transformer & inductor design
  • Ferrite · powdered iron · laminated steel cores
  • FEMM: transformers, motors, electromagnets

Power

  • SiC · GaN · IGBT
  • Power PCB layout
  • Pulsed thermal design
  • Solar DC-DC
  • MPPT & shade-tolerant PV
  • Battery charging & BMS
  • "OMG It keeps exploding!" fixes

Also

  • Signal integrity
  • FPGA & CPLD gateware
  • Patent artwork & writing
  • Mechanical CAD/CAM & FEA

Software

  • KiCad
  • FreeCAD
  • FEMM
  • Sonnet EM
  • STM32CubeIDE
  • MPLAB X
  • LTspice
  • QSPICE
  • PSpice
  • TINA-TI
  • Android Studio
  • Git
  • Linux (Debian, Arch)

Selected past work

Green control board mounted in the welder chassis, wired between large blue capacitors and the power stage
Control logic for 2 kA pulsed TIG welder with pulse forming
Inverter power board with toroidal inductors, 450 V bulk capacitors and heatsinked switches in its enclosure
1 kW AC-to-AC arbitrary waveform generator / inverter
Compact control board with a dsPIC microcontroller and a hand-wound toroidal transformer
Analog and RF electronics for a blend electrolysis machine
LEV 6 control board with a microcontroller, USB port and labeled UART, OUT and SENSE headers
Inductive proximity sensing and DSP control for EM levitation
Purple steel-frame gantry mill with a spindle on linear rails above a drilled aluminum table
Custom CNC gantry milling machine
Purple CC Boost Rev 1 driver board with a large power inductor, mounted on a black finned heatsink
Constant-current boost LED driver
Bridge board with screw-terminal IGBT modules and a white film capacitor on a finned aluminum heatsink
200 A IGBT full bridge
Inductor Blaster test board with pulse button and current-limit knob, clipped to a wound test inductor
Pulsed inductor saturation tester

A hobby first, a career second

I started building circuits on breadboards around age twelve, competed in regional science fairs through high school and placed at ISEF. I studied electrical engineering with an emphasis on control loop design, then spent ten years at an RF and microwave design firm before going out on my own as a consultant.

After years of consulting, I'm now full-time at a Bay Area startup and loving it. Along the way I've become a named inventor on four patents: two granted and two pending. I still tinker on my own time — this site collects the projects and tools that came out of all of it.

My love of EE and Mech E has never faded and I hope it never does. Engineering for me is a wonderfully creative field that seems to be open and limitless. Over the years my greatest areas of interest have moved between analog, RF engineering, and power electronics. I'm currently in a long phase of pushing the limits of what Si, GaN, and custom magnetics can do for high efficiency power conversion.

Equipment I own

Oscilloscopes, spectrum analyzers, DMMs, and power supplies for accurate measurements.

Soldering stations including hot air, plus microscopes for fine-pitch work.

An extensive collection of parts and prototyping supplies.

An engine Lathe and granite CNC mill for mechanical prototypes.

10K resin printer for production-quality plastic parts.

FDM printer for fast functional prototypes.