01
Motor-drive layout
Half-bridge gate loops, shunt sensing and current-feedback paths laid out for clean FOC operation at MHz-class PWM — without rattling the encoder analog.
Hardware that moves — without falling over itself.
Robotics PCBs put a fast-switching motor drive next to a quiet MCU next to an encoder, in a vibrating enclosure with a tight EMC budget. We design layouts that respect every one of those constraints — not just the one in the datasheet.
BLDC + PMSMFOC motor drives
kHz – MHzcontrol + telemetry
CISPR 11industrial EMC
FuSa-awareISO 13849 / IEC 61508
The deliverables.
02
Mixed-signal partitioning
MCU + analog sensing + power on the same board, planned as zones with controlled returns — not a hope and a guard ring.
03
EMC discipline
CISPR 11 emissions controlled at the source: dV/dt management, shielded sensor cabling layout, common-mode filter design at the inverter pin.
04
Sensor + bus integration
Encoder, IMU, CAN-FD, EtherCAT and SPI sensor interfaces — terminated, shielded and timed, with safety partitioning where the standard demands it.
Built for this sector.
Standards we design to
- CISPR 11 / EN 61000-6 (industrial EMC)
- ISO 13849 / IEC 61508 (functional safety, supporting)
- IEC 61000-4-x (ESD / surge / EFT)
- ISO 26262 (mobile / AMR roles)
- IPC Class 2 / 3 reliability
Motion + power
- BLDC / PMSM / stepper drives
- FOC — sensored and sensorless
- GaN / SiC inverters where speed matters
- Regen + brake-chopper management
- Bus-bar + capacitor-bank layout
Sensing + comms
- Encoder, IMU, force-torque front-ends
- EtherCAT, CAN-FD, SPI sensor
- Quiet ADC layout near switching
- Optical / magnetic isolation barriers
- Cable and shield management
A 6-axis cobot joint passing CISPR 11 on the first article.
The brief
A 200 W joint controller on a collaborative robot was failing CISPR 11 conducted emissions by ~8 dB and confusing its own encoder during high-speed moves.
What we did
- Re-laid the gate loop and switched the input filter from a generic π to a CMC-first topology — conducted emissions dropped ~12 dB.
- Moved the encoder analog onto a stitched quiet island over a continuous ground, away from the switching half-bridge.
- Partitioned the safety inputs onto an independent supply with diagnostic feedback, supporting the customer’s ISO 13849 PL-d argument.
Outcome
CISPR 11 Class A passed with ~4 dB margin; encoder false-counts went from ~1/min to none over a 48-hour soak.
Common questions.
Can you design GaN-based motor drives?
Yes — that’s where the encoder-noise problem gets interesting. The faster the edges, the more your layout choices matter. We measure loop inductance and dV/dt at the gate, not just simulate them.
Do you support PL-d / SIL-3 / ASIL-D layouts?
Yes — independence between channels, diagnostic coverage and redundancy partitioning. The certification and assessment work is yours; the layout that makes it possible is ours.
Can you do the end-of-arm + body controllers too?
Yes — many robotics engagements span the joint, body controller and tool boards as a stack, so the EMC and power budgets work together rather than against each other.
Robotics PCB engineering challenges
- Motor drive layout: 100 A BLDC half-bridge: gate drive loop must be <5 nH. Bootstrap cap must be within 5 mm of the high-side switch. Kelvin-sense resistor shares no copper with the high-current path. Getting this wrong means shoot-through at 48 V — catastrophic failure.
- IMU isolation: A 6-DOF IMU on the same board as a 48 V motor driver requires physical isolation — cut copper under the IMU, keep it away from power switching, and use soft-mount PCB standoffs if vibration >2g. Embedding the IMU 2 mm from a half-bridge is how you get garbage odometry data.
- Size vs. current: Modern joint actuator boards: 48 V, 30 A per axis, <60 mm square. 2 oz copper, multi-phase buck, thermal vias under every FET. We’ve designed to this envelope. TRM validates the thermal budget before tape-out.
- CAN FD and EtherCAT: 5 Mbps CAN FD needs 120 Ω termination, stub length <10 mm, differential pair impedance 120 Ω. EtherCAT at 100 Mbps full-duplex is Ethernet under the hood — follow 100BASE-TX layout rules. We don’t guess; we calculate.
Make the motion smooth — and quiet.
Motor drives, sensing and EMC, designed as one system. Fixed-fee band in 60 seconds.