2 layers159 × 159 mm
Pdh v2
vuthalab/pdh_servo_v2
A servo controller for locking lasers to high-finesse cavities
156 parts8MIT
4 layers70 × 70 mm
Gpsdo
AndreasArendt/gpsdoLow cost GPS Disciplined Oscillator
- Size
- 70 × 70 mm
- Copper layers
- 4
- Thickness
- 1.6 mm
- Parts
- 88
- Nets
- 75
- Pads
- 316
- Tracks, vias
- 455, 104
- Pours
- 7
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 3 Sep 2025
- Updated
- 25 Nov 2025
Overview
Gpsdo is an open-source printed circuit board by AndreasArendt, from the AndreasArendt/gpsdo repository on GitHub, published under the MIT licence. It is a 4-layer board of 70 × 70 mm with 88 parts on 75 nets, routed with 455 tracks and 104 vias.
It is built around the SN74LVC1G125DBV, AD5541ARZ and SN74LVC1T45DCK, with the 74HC161S, AMS1117-3.3 and NTCG103JF103FT1 among its other parts. Its parts include 40 capacitors, 14 resistors, 9 ICs, 5 connectors and 3 diodes. It belongs with the STM32 boards of this library.
Main components
7
SN74LVC1G125DBV
SOT-23-5-40℃~+125℃ 1 1 1.65V~5.5V 10uA 3.7ns@3.3V,15pF 32mA 32mA 74LVC Tri-State Unidirectional SOT-23-5 Buffers, Drivers, Receivers, Transceivers ROHSTexas InstrumentsSpecialty Logic
AD5541ARZ
SOIC-8-40℃~+85℃ 1 125uA 16 1us 2.7V~5.5V 4LSB Power-on reset SPI、QSPI Voltage-Unbuffered SOIC-8 Digital to Analog Converters (DAC) ROHSAnalog DevicesDigital To Analog Converters (DACs)
SN74LVC1T45DCK
SC-70-6-40℃~+85℃ 1 1 1.65V~5.5V 1.65V~5.5V 420Mbps Bidirectional Level translator Power-off protection、Output enable high-impedance Tri-State SC-70-6 Translators, Level Shifters ROHSTexas InstrumentsTranslators, Level Shifters
74HC161S
SOP-160℃~+70℃ 20MHz 2V~6V 4 500mW Asynchronous Hexadecimal Counter Rising Edge Synchronous Up Counter SOP-16 Counters, Dividers ROHSGRCounters, Dividers
AMS1117-3.3
SOT-223-40℃~+125℃ 0.003%Vout 1 1.1V@(800mA) 15V 1A 3.3V 5mA 72dB@(120Hz) Fixed Over Current Protection、Short Circuit Protection、Thermal shutdown Positive SOT-223 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSAdvanced Monolithic SystemsVoltage Regulators - Linear, Low Drop Out (LDO) Regulators
NTCG103JF103FT1
0402-40℃~+125℃ 0.5mm 0.5mm 100mW 10kΩ 1mW/℃ 1mm 310uA 3380K 3422K 3435K 3453K ±1% ±1% 0402 NTC Thermistors ROHSTDKNTC Thermistors
X322516MLB4SI
SMD3225-4P-40℃~+85℃ 16MHz 50Ω 9pF Crystal Oscillator ±10ppm ±20ppm SMD3225-4P Crystals ROHSYXCCrystals
README
README.mdGPSDO
GPSDO (GPS Disciplined Oscillator) combines the precision of a high-quality OCXO (Oven-Controlled Crystal Oscillator) with the pulse-per-second (PPS) signal from a GNSS receiver. The goal is to achieve accurate time and frequency reference, down to the nanosecond level.
This project aims to create an open-source and affordable GPSDO from scratch, including designing custom hardware (PCB) and developing the supporting software.
Features
- Combines GNSS PPS with a high-precision OCXO
- Fully open-source hardware and software
- Targeting nanosecond-level timing precision
- Modular design for hardware and software development
Status
🚧 Under Construction
- The first hardware prototype is currently being tested; all findings are documented in Issue #1
- A Kalman-Filter to estimate
phase,frequency_offsetandfrequency_drifthas been implemented - A PI-Controller is running the GPSDO closed loop
- Flatbuf Messages are implemented to ensure easy-to-extend communication to a host system
Roadmap
✅ Improve hardware based on findings from V2 prototype
🔄 Integrate the GNSS receiver on-board for a fully standalone GPSDO
⚙️ Fine-tune the control loop and filtering algorithms
📊 Benchmark the true performance against reference standards
Contributing
Contributions are welcome! Whether it's hardware design suggestions, software improvements, or analysis scripts, feel free to open an issue or a pull request.
Compiling flatcc (Windows)
- Navigate into
flatccsubmodule folder. - Create
buildfolder - Navigate into
buildfolder - Run
cmake .. - Run
cmake --build . --config Release - Executable is in
flatcc/bin/Release/flatcc.exe
Parts
88| Qty | Value | Footprint | References |
|---|---|---|---|
| 26 | 100n | Capacitor_SMD:C_0603_1608Metric | C1, C2, C11, C14, C15, C19, C20, C21, C22, C23, C24, C27, C31, C32, C33, C34 +10 |
| 6 | 10u | Capacitor_SMD:C_0603_1608Metric | C3, C10, C13, C28, C29, C30 |
| 4 | 1u | Capacitor_SMD:C_0603_1608Metric | C6, C12, C26, C36 |
| 3 | 1.1k | Resistor_SMD:R_0603_1608Metric | R12, R13, R14 |
| 3 | 100 | Resistor_SMD:R_0603_1608Metric | R1, R5, R6 |
| 3 | 10k | Resistor_SMD:R_0603_1608Metric | R7, R9, R17 |
| 3 | 33 | Resistor_SMD:R_0603_1608Metric | R4, R8, R18 |
| 3 | LED | LED_SMD:LED_0805_2012Metric_Pad1.15x1.40mm_HandSolder | D1, D2, D3 |
| 3 | LOGO | LOGO | G***, G***, G*** |
| 3 | NetTie_2 | NetTie:NetTie-2_THT_Pad0.3mm | NT1, NT2, NT3 |
| 2 | 12p | Capacitor_SMD:C_0603_1608Metric | C16, C17 |
| 2 | 22k | Resistor_SMD:R_0603_1608Metric | R15, R16 |
| 2 | 4.7u | Capacitor_SMD:C_0603_1608Metric | C18, C25 |
| 2 | SN74LVC1T45DCK | Package_TO_SOT_SMD:SOT-363_SC-70-6 | U1, U2 |
| 2 | TestPoint | TestPoint:TestPoint_Pad_D1.5mm | TP1, TP3 |
| 1 | 10uH | Inductor_SMD:L_0603_1608Metric | L1 |
| 1 | 74HC161 | Package_SO:SO-16_3.9x9.9mm_P1.27mm | U8 |
| 1 | AD5541A | Package_SO:MSOP-10_3x3mm_P0.5mm | U4 |
| 1 | AMS1117-3.3 | Package_TO_SOT_SMD:SOT-223-3_TabPin2 | U7 |
| 1 | Conn_01x02 | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | J1 |
| 1 | Conn_01x05 | Connector_PinHeader_2.54mm:PinHeader_1x05_P2.54mm_Vertical | J7 |
| 1 | Conn_02x03_Top_Bottom | Connector_PinHeader_2.54mm:PinHeader_2x03_P2.54mm_Vertical | J2 |
| 1 | Conn_Coaxial | Connector_Coaxial:SMA_Samtec_SMA-J-P-H-ST-EM1_EdgeMount | J5 |
| 1 | NTCG103JF103FT1 | Resistor_SMD:R_0603_1608Metric | TH1 |
| 1 | OPA197xD | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U5 |
| 1 | REF5040AD | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U3 |
| 1 | SN74LVC1G125DBV | Package_TO_SOT_SMD:SOT-23-5 | U9 |
| 1 | STM32F411CEUx | Package_DFN_QFN:QFN-48-1EP_7x7mm_P0.5mm_EP5.6x5.6mm | U6 |
| 1 | TestPoint | TestPoint:TestPoint_Pad_D1.0mm | TP2 |
| 1 | USB_C_Receptacle_USB2.0_14P | Connector_USB:USB_C_Receptacle_G-Switch_GT-USB-7010ASV | J3 |
| 1 | X322516MLB4SI | Crystal:Crystal_SMD_3225-4Pin_3.2x2.5mm | X1 |
| 1 | ~ | OCXO:OSC5A2B02 | OSC5A2B1 |
The 84 most common of 88 parts.
Questions
How big is the Gpsdo PCB?
It measures 70 × 70 mm and has 4 copper layers, 1.6 mm thick.
What parts does the Gpsdo use?
88 parts, built around the SN74LVC1G125DBV, AD5541ARZ, SN74LVC1T45DCK and 74HC161S. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Gpsdo KiCad files?
From the AndreasArendt/gpsdo repository on GitHub, at the commit this page was made from: the board is hardware/gpsdo/gpsdo.kicad_pcb and its schematic hardware/gpsdo/Microcontroller.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Gpsdo design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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