AnalogadvancedanalogADCop-ampfiltersignal conditioning

ADC Frontend with Filtering

Op-amp signal conditioning front-end with anti-aliasing filter and input protection. Designed for interfacing 0–5 V industrial sensors to 3.3 V MCU ADC inputs.

Connecting sensors to microcontroller ADCs requires careful attention to gain, offset, bandwidth limiting, and protection. This template provides a configurable two-stage op-amp circuit: a differential input buffer with CMRR optimisation followed by a 4th-order Butterworth anti-aliasing filter. The design notes include the filter coefficient calculator spreadsheet and explain how to adapt the passband frequency and gain for different sensor output ranges.
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What's included

  • KiCad Schematic (.kicad_sch)

    With filter coefficient annotation

  • KiCad PCB Layout (.kicad_pcb)

    Analog ground split, 2-layer

  • Gerber + drill files

    Fab-ready package

  • BOM (Excel + CSV)

    EU distributors

  • Design Notes PDF

    Gain, filter, protection design explanation

  • Filter calculator spreadsheet (.xlsx)

    Recalculate for your cutoff frequency

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Technical Specifications

Op-ampOPA2197 (rail-to-rail, low-offset)
Input range0 V – 5 V single-ended or ±2.5 V differential
Output range0 V – 3.3 V (MCU ADC compatible)
Anti-aliasing4th-order Butterworth, 10 kHz default
Input protectionDiode clamps + series R to IEC 61000-4-2 ±2 kV
PCB size30 × 20 mm, 2-layer

FAQ

What KiCad version do the files use?

All files are saved in KiCad 8.x format. They open in KiCad 7 with a one-time migration dialog.

Can I use the template in a commercial product?

Yes. Once purchased, you receive a perpetual licence to use and modify the design in any number of products, including commercial ones.

Are the BOMs kept up to date?

We review BOMs quarterly and push updates when components are discontinued or better alternatives become available. All updates are free.

What if my fab parameters differ (e.g. 4-layer board)?

The design notes explain which constraints are fab-specific. Upgrading to a 4-layer stack is straightforward and covered in the integration guide.

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