PCB Design for Low-Power Sensor System

flux

3:14

Chat History
Project
Review (ERC/DRC)
Schematic
Accessed Knowledge (3)

Using Knowledge Base Tool.

Using Review (ERC/DRC) Tool.

Using Schematic Tool.

Here’s what still needs correction before you can create the PCB, plus practical workarounds where needed.
Critical blockers to fix first
  • Power net short into ground:
    • GND contains IC1, U2, U2, and U3 (fatal).
    • Fix:
      • Create a 1V8 net. Connect U2 → 1V8 → IC1, U3, temp sensor VDD.
      • Rewire decouplers so each cap has P1 to its supply (1V8 or VIN) and P2 to GND. Right now many P1 pins are on GND.
      • Ensure U2 is ONLY tied to the piezo input path (via J1), not to GND.
  • RF airwire:
    • DRC shows an airwire between IC1 and J2. You must hand-route this 50 Ω trace and add the via-fence/keepout.
  • TIA and I2C connectivity gaps:
    • Airwires: R6–R7–R8 junction not fully connected; U3 not actually tied to 1V8; IC1/IC1 to pull-ups show missing routes.
  • Temperature sensor part mismatch:
    • U4 is TT8M2TR (not STTS22H). Replace with STTS22H (preferred) or TMP117, then wire VDD to 1V8, GND to GND, SDA/SCL to IC1/IC1.
  • Missing MPNs for generics:
    • DRC “Manufacturer Part Number” errors on nearly all generics (R10, R11, C18, C19, C20, C21, C22, C23, etc.). Replace each with a real library part to clear manufacturing checks.
High-priority corrections (guided by best practices)
  • Decoupling (authoritative KB):
    • Use a typical capacitor combo “100 nF + 1 µF + 10 µF” per rail for high/low-frequency coverage and place 100 nF within 5 mm of each VDD/GND pair.
    • Apply to: IC1 with C18/C19 + a bulk (e.g., C8 or C17); U2 with C20/C21 and C22/C23; U3 with a local 100 nF.
  • I2C pull-ups (authoritative KB):
    • Base value on bus capacitance (spec max is “400 pF”) and 100 kHz. Lower resistance improves edge rates but increases sink/idle current. At 1.8 V, typical starting values are 4.7 kΩ for short, low-capacitance buses; move to 2.2 kΩ if the layout or cable adds capacitance. Remember idle current is VDD/Rpu continuously.
    • Action: Replace R10, R11 with real 1.8 V pull-ups (e.g., 4.7 kΩ 0603) tied to 1V8, not GND.
  • Ground/returns (authoritative KB):
    • Prevent switching ground bounce from coupling into the TIA by ensuring the return path for the TIA around U3 is not shared with U2’s switching loop. Prefer a continuous ground plane; steer returns using placement and stitching, guard sensitive nodes, and avoid hard split planes unless absolutely required.
RF path to finish
  • Route the RF net:
    • Hand-route IC1 → J2 straight and short on the top layer over a continuous ground reference layer. Add a via-fence along both sides of the trace.
  • Keepouts:
    • Add a keepout around the RF pad/trace (2 mm around the launch you specified). Single-layer is fine; use a Zone if you later need multi-layer cutouts.
Schematic-specific fixes (seen in current nets)
  • Move these pins off GND and onto proper nets:
    • IC1 → 1V8
    • U3 → 1V8
    • U2 → 1V8
    • U2 → piezo input only (from J1)
    • Ensure each decoupler P1 goes to its supply net, and P2 goes to GND.
  • TIA network:
    • The R6/R7/R8 junction is unrouted. Complete the inverting node connections, and connect the TIA output through R9/C7 to the ADC pin on IC1.
    • Values currently read as 500 Ω. For pA–µA work, populate at least one high-value option (1 MΩ or 10 MΩ) footprint; use a guard ring around the inverting input. Consider switching the feedback legs with a low-leakage analog switch rather than GPIO, if leakage becomes a problem.
  • Harvester configuration:
    • Strap U2 for a 1.8 V output setting; wire PGOOD if used. Size/attach the output storage cap per datasheet on CAP/VOUT (you already have C11/C5, verify values).
Layout readiness issues
  • Board outline is huge (about 1005 × 1652 mm). Shrink to a realistic footprint target for your device (for example 20 × 20 mm as a starting point) to shorten traces and reduce parasitics before routing.
  • Ensure Layer 2 is a continuous ground plane beneath the RF trace and the TIA. Stitch ground around the RF and around the TIA guard area.
Workarounds if something isn’t solvable immediately
  • Temp sensor availability:
    • If STTS22H cannot be placed now, use TMP117 temporarily. Both are I2C at 1.8 V; keep the same pull-ups and decoupling.
  • TIA gain switching/leakage risk:
    • If GPIO-controlled ladder injection is problematic, switch to a low-leakage analog switch (e.g., search: TS5A3359 or ADG819) to select feedback resistors without loading the inverting node.
  • 50 Ω constraint:
    • If you can’t compute exact CPWG width with your current stackup, keep the RF trace as short/straight as possible over a solid ground plane, use a conservative keepout, and match the connector launch with tight ground via fencing. You can refine trace width later with an impedance calculator without upsetting most of the layout.
DRC/Manufacturing to close out
  • Route all airwires flagged in DRC:
    • [IC1:RFIOP] ↔ [J2:1], [R6:P2]–[R7:P2]–[R8:P2], [IC1:GPIO03] ↔ [R11:P2], [U3:V+] ↔ 1V8 from [U2:VOUT], etc.
  • Replace generics with real library parts (assign MPNs) for resistors and capacitors:
Would you like me to prepare a small, ordered fix list you can run (power net de-merge → sensor replacement → I2C pull-up values → TIA wiring → RF route → MPN updates)? I can also create a plan to apply these changes automatically and then re-run DRC.
138 days
flits101

flits101

Yes, please outline the ordered fix list you mentioned.
138 days

flux

0:32

138 days
Sign up to send
U2 VIN - U2 VOUT
C4
Capacitance
100nF
C1
Capacitance
100nF
C3
Capacitance
100nF
U2 EP - C4 P2
C4 P2 - C11 P2
GND
C2
Capacitance
100nF
C5
Capacitance
10uF
  • Ground
    Ground
    A common return path for electric current. Commonly known as ground.
    jharwinbarrozo
    20.5M
  • Net Portal
    Net Portal
    Wirelessly connects nets on schematic. Used to organize schematics and separate functional blocks. To wirelessly connect net portals, give them same designator. #portal
    jharwinbarrozo
    43.0M
  • Power Net Portal
    Power Net Portal
    Wirelessly connects power nets on schematic. Identical to the net portal, but with a power symbol. Used to organize schematics and separate functional blocks. To wirelessly connect power net portals, give them the same designator. #portal #power
    jharwinbarrozo
    11.4M
  • Generic Resistor
    Generic Resistor
    A generic fixed resistor for rapid developing circuit topology. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard resistor values: 1.0Ω 10Ω 100Ω 1.0kΩ 10kΩ 100kΩ 1.0MΩ 1.1Ω 11Ω 110Ω 1.1kΩ 11kΩ 110kΩ 1.1MΩ 1.2Ω 12Ω 120Ω 1.2kΩ 12kΩ 120kΩ 1.2MΩ 1.3Ω 13Ω 130Ω 1.3kΩ 13kΩ 130kΩ 1.3MΩ 1.5Ω 15Ω 150Ω 1.5kΩ 15kΩ 150kΩ 1.5MΩ 1.6Ω 16Ω 160Ω 1.6kΩ 16kΩ 160kΩ 1.6MΩ 1.8Ω 18Ω 180Ω 1.8KΩ 18kΩ 180kΩ 1.8MΩ 2.0Ω 20Ω 200Ω 2.0kΩ 20kΩ 200kΩ 2.0MΩ 2.2Ω 22Ω 220Ω 2.2kΩ 22kΩ 220kΩ 2.2MΩ 2.4Ω 24Ω 240Ω 2.4kΩ 24kΩ 240kΩ 2.4MΩ 2.7Ω 27Ω 270Ω 2.7kΩ 27kΩ 270kΩ 2.7MΩ 3.0Ω 30Ω 300Ω 3.0KΩ 30KΩ 300KΩ 3.0MΩ 3.3Ω 33Ω 330Ω 3.3kΩ 33kΩ 330kΩ 3.3MΩ 3.6Ω 36Ω 360Ω 3.6kΩ 36kΩ 360kΩ 3.6MΩ 3.9Ω 39Ω 390Ω 3.9kΩ 39kΩ 390kΩ 3.9MΩ 4.3Ω 43Ω 430Ω 4.3kΩ 43KΩ 430KΩ 4.3MΩ 4.7Ω 47Ω 470Ω 4.7kΩ 47kΩ 470kΩ 4.7MΩ 5.1Ω 51Ω 510Ω 5.1kΩ 51kΩ 510kΩ 5.1MΩ 5.6Ω 56Ω 560Ω 5.6kΩ 56kΩ 560kΩ 5.6MΩ 6.2Ω 62Ω 620Ω 6.2kΩ 62KΩ 620KΩ 6.2MΩ 6.8Ω 68Ω 680Ω 6.8kΩ 68kΩ 680kΩ 6.8MΩ 7.5Ω 75Ω 750Ω 7.5kΩ 75kΩ 750kΩ 7.5MΩ 8.2Ω 82Ω 820Ω 8.2kΩ 82kΩ 820kΩ 8.2MΩ 9.1Ω 91Ω 910Ω 9.1kΩ 91kΩ 910kΩ 9.1MΩ #generics #CommonPartsLibrary
    jharwinbarrozo
    1.5M
  • Generic Capacitor
    Generic Capacitor
    A generic fixed capacitor ideal for rapid circuit topology development. You can choose between polarized and non-polarized types, its symbol and the footprint will automatically adapt based on your selection. Supported options include standard SMD sizes for ceramic capacitors (e.g., 0402, 0603, 0805), SMD sizes for aluminum electrolytic capacitors, and through-hole footprints for polarized capacitors. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard capacitor values: 1.0pF 10pF 100pF 1000pF 0.01uF 0.1uF 1.0uF 10uF 100uF 1000uF 10,000uF 1.1pF 11pF 110pF 1100pF 1.2pF 12pF 120pF 1200pF 1.3pF 13pF 130pF 1300pF 1.5pF 15pF 150pF 1500pF 0.015uF 0.15uF 1.5uF 15uF 150uF 1500uF 1.6pF 16pF 160pF 1600pF 1.8pF 18pF 180pF 1800pF 2.0pF 20pF 200pF 2000pF 2.2pF 22pF 20pF 2200pF 0.022uF 0.22uF 2.2uF 22uF 220uF 2200uF 2.4pF 24pF 240pF 2400pF 2.7pF 27pF 270pF 2700pF 3.0pF 30pF 300pF 3000pF 3.3pF 33pF 330pF 3300pF 0.033uF 0.33uF 3.3uF 33uF 330uF 3300uF 3.6pF 36pF 360pF 3600pF 3.9pF 39pF 390pF 3900pF 4.3pF 43pF 430pF 4300pF 4.7pF 47pF 470pF 4700pF 0.047uF 0.47uF 4.7uF 47uF 470uF 4700uF 5.1pF 51pF 510pF 5100pF 5.6pF 56pF 560pF 5600pF 6.2pF 62pF 620pF 6200pF 6.8pF 68pF 680pF 6800pF 0.068uF 0.68uF 6.8uF 68uF 680uF 6800uF 7.5pF 75pF 750pF 7500pF 8.2pF 82pF 820pF 8200pF 9.1pF 91pF 910pF 9100pF #generics #CommonPartsLibrary
    jharwinbarrozo
    1.5M
  • Generic Inductor
    Generic Inductor
    A generic fixed inductor for rapid developing circuit topology. *You can now change the footprint and 3D model at the top level anytime you want. This is the power of #generics
    jharwinbarrozo
    15.5k
  • Terminal
    Terminal
    An electrical connector acting as reusable interface to a conductor and creating a point where external circuits can be connected.
    natarius
  • RMCF0805JT47K0
    RMCF0805JT47K0
    47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film #forLedBlink
    jharwinbarrozo
    1.2M
  • 875105359001
    875105359001
    10uF Capacitor Aluminum Polymer 20% 16V SMD 5x5.3mm #forLedBlink #commonpartslibrary #capacitor #aluminumpolymer #radialcan
    jharwinbarrozo
    1.2M
  • CTL1206FYW1T
    CTL1206FYW1T
    Yellow 595nm LED Indication - Discrete 1.7V 1206 (3216 Metric) #forLedBlink
    jharwinbarrozo
    1.1M
Alert Rose TARDIS thumbnail
Ultra-Low-Power 1.8V Piezoelectric Energy Harvesting RF Sensor Node with Apollo3 Blue, LTC3588-1, STTS22H, and OPA333

Properties

mm
mm
mm
mm
mm
mm
V
mm
mm
mm

Pricing & Availability

Distributor

Qty 1

Assets

No assets added.

Controls