Senior Mixed-Signal Embedded Hardware Engineer

We are developing a high-precision acoustic/vibration Time Difference of Arrival (TDOA) positioning system. The core architecture has already been proven using a combination of development kits:

• dsPIC Nano dev kit - acts as a precision digital TDOA timing simulator with correct, repeatable timing.

• dsPIC33CK Curiosity Development Board - processes TDOA signals using high-speed, synchronized ADC acquisition.

• Custom Analog Front End (AFE) PCB - buffers and filters real piezoelectric vibration sensor signals.

These boards currently communicate with each other and a host over USB, which also supplies power and firmware/debug access.

The Objective

We are moving from this multi-board proof-of-concept to a single, consolidated, highly optimized integrated PCB assembly. We need a Senior Mixed-Signal Hardware Engineer to design a custom board that merges our proven MCU architecture and analog front-end into one high-performance prototype that:

• Matches or exceeds the performance of the current dev-kit prototype.

• Seamlessly supports both the digital TDOA simulator and the real analog vibration sensors.

• Is ready for the next stage of product development and field testing.

Hardware Architecture & Scope

The resulting integrated assembly must provide:

1. ESP32-S3 Controller (DevKitC-1 equivalent): acts as the master TDOA controller and provides BLE services for result processing. USB-powered if the power budget allows, with USB also used for firmware updates and debugging.

2. Analog & Driver I/O: external connections for 3 high-impedance analog vibration sensors, plus a driver output for a calibration buzzer.

3. dsPIC33CK Integration: full support circuitry to operate, flash, and debug the dsPIC33CK DSP/MCU; serial communications with the ESP32-S3; and 3 synchronized high-speed ADCs for high-resolution TDOA processing.

4. Mixed-Signal Optimization: careful optimization of analog inputs, PCB layout, ground planes, and decoupling to preserve nanosecond-level timing accuracy and low-noise ADC performance.

5. Dual-Input Testing Capability: a clean, swappable input path that supports testing via either the digital dsPIC TDOA simulator (correct timing, logic-level output) or the three real analog vibration sensors.

Key Responsibilities

• Review & Reconstruct: review the current dev-kit/breadboard approach and reconstruct a complete, production-ready schematic, comparing it against the working AFE and dev kits.

• Circuit Correction: optimize and correct power, reset, oscillator, programming, and high-speed ADC circuitry.

• PCB Layout: create, update, and correct the 4-layer mixed-signal PCB layout with a strict focus on signal integrity, phase matching, and noise isolation.

• Manufacturing: prepare manufacturing files (Gerbers, BOM, Pick & Place, assembly drawings) and resolve assembly-house queries.

• Bring-Up & Debug: lead first-article board bring-up - power-on tests, supply rail and ripple/noise verification, flashing and debugging both MCUs, and validating communication, timing, and TDOA simulator results.

• Iterate & Repair: diagnose first-round prototype issues, repair/rework boards where practical, and iterate the schematic/layout for the final version.

• Ideal candidate: a senior mixed-signal embedded hardware engineer with direct experience designing boards around Microchip dsPIC33 (or similar 16-bit MCUs).

• Next-best candidate: a senior mixed-signal engineer who has designed boards around similar-class MCUs (PIC32, STM32, etc.) and can meticulously follow Microchip datasheets, reference schematics, and hardware-design guidance.

Required Experience - must demonstrate previous designs involving at least TWO of the following:

• Piezoelectric or other high-impedance sensors

• High-speed, multi-channel analog acquisition

• Low-noise amplifiers (LNAs)

• Audio-frequency or ultrasonic signal processing

• Precision timing or phase measurement

• ADC channel matching

• MCU-based DSP hardware integration

• Four-layer (or more) mixed-signal PCB layout, * Do you have mixed signal experience?
• Do you have DS PIC (Digital Signal processing chip) experience?
• Do you have TDOA (time delay of arrival) experience?

$80 - $130 an hour - Contract, Pulled from the full job description

• Flexible schedule, * Flexible schedule