Arbitrary Waveform Generator
Developing a portable, dual-channel arbitrary waveform generator with wireless iOS app control over Bluetooth Low Energy (BLE). Designed by a four-person team, the system integrates an ESP32-S3 microcontroller, Xilinx Spartan-6 FPGA, and a 16-bit DAC with precision analog filtering and output amplification.
The instrument targets a 250 kHz maximum waveform frequency, ±5 V output range, and 6.25 MS/s sampling rate per channel. The hardware features custom four-layer PCBs, rechargeable battery operation, and USB-C connectivity.
My primary responsibilities include the DAC and precision analog subsystem, mixed-signal circuit design, and FPGA/DAC/analog PCB layout.
LINKS
Links to project files temporarily confidential.
ROLE
PROBLEM
Design a compact, battery-powered waveform generator capable of producing two independent, high-resolution analog signals while maintaining waveform accuracy, low distortion, and sufficient output-drive capability.
The primary engineering challenges include high-speed digital-to-analog conversion, analog reconstruction filtering, driving 50 Ω loads, and minimizing noise and interference between digital and precision analog circuitry within a custom PCB.
RESULTS
Designed and routed a custom four-layer PCB integrating FPGA logic, high-speed DAC circuitry, precision analog signal conditioning, and output stages using KiCad.
Designed precision reference and local power-distribution circuitry, incorporating regulated supply rails, component decoupling, ground planes, and mixed-signal PCB layout practices.
Coordinated FPGA-to-DAC interfaces and subsystem interconnections, completing PCB layout and preparing the hardware for fabrication, assembly, and electrical validation.
A lab instrument, made portable
Traditional waveform generators are powerful laboratory instruments, but their size and dependence on external power limit portability. Our four-person team is developing a compact alternative that produces two independently programmable analog waveforms, controlled wirelessly through an iOS application over Bluetooth Low Energy (BLE).
The system combines an ESP32-S3 microcontroller, a Xilinx Spartan-6 FPGA, and a 16-bit digital-to-analog converter (DAC) with precision analog output circuitry. Our design targets a 250 kHz maximum waveform frequency, ±5 V output range, and 6.25 MS/s sampling rate per channel.
Engineering the analog signal chain
I am responsible for the DAC and precision analog subsystem, which converts digital waveform samples from the FPGA into continuous analog signals suitable for driving external loads.
The design uses an AD3542R 16-bit DAC feeding two independent fourth-order Bessel reconstruction filters and OPA564 output amplifiers. The filters suppress unwanted high-frequency components introduced by digital-to-analog conversion while preserving waveform shape. The output amplifiers provide the current-driving capability needed to achieve the target ±5 V output into 50 Ω loads.
I also worked extensively on the custom four-layer FPGA/DAC/analog PCB in KiCad, integrating high-speed digital interfaces, precision voltage references, regulated power rails, and analog output circuitry. Particular attention was given to component placement, decoupling, grounding, and signal routing to reduce interference between digital and analog sections.
Hardware integration & validation
With the FPGA/DAC/analog PCB design completed and submitted for fabrication, the project is transitioning from circuit design to hardware assembly and testing.
Upcoming validation will focus on DAC communication, output voltage accuracy, waveform fidelity, frequency response, and performance under 50 Ω loading. Oscilloscope measurements will be used to compare actual output behavior against the design requirements.
The project provides hands-on experience developing a complete mixed-signal system, from component selection and schematic design to PCB implementation and hardware verification.