# Sensor signal-conditioning PCB

Unique Acevedo — Planning brief

**Planned · not started. These are proposed requirements and tests, not achieved results.**

My op-amp lab gave me experience building and testing transistor-level circuits. For this project, I want to carry that approach into a small PCB: define the signal first, choose the gain and filtering, then compare the design with measurements. The sensor, amplifier, ADC, and operating limits still need to be selected.

## Write the requirements before choosing parts

Start with input range, source impedance, supply, output range, bandwidth, and load. Those decisions will set the amplifier headroom, gain settings, filter, and test conditions.

## Model the first signal path

Use the ideal non-inverting gain G = 1 + Rf/Rg and first-order cutoff fc = 1/(2πRC) as starting points. Then check input common-mode limits, output swing, bandwidth, slew rate, tolerances, loading, and stability against the selected parts.

## Make the board measurable

Include accessible test points, legible reference designators, and a documented power-up procedure. Keep schematic, footprint selection, BOM, layout, and fabrication outputs tied to a named revision.

## Connect the ADC after characterizing the front end

Begin with a controlled input. Once an ADC is selected, account for its input network and acquisition time. A correct static voltage does not establish that the input settles quickly enough during sampling.

## How I plan to test it

- [ ] Review selected footprints and save ERC/DRC results, including explanations for intentional exceptions.
- [ ] Measure DC transfer behavior across the specified range at every gain setting and check for clipping.
- [ ] Sweep frequency below, through, and above the intended cutoff; compare measurements with simulation.
- [ ] Set numerical pass limits from component tolerances and measurement uncertainty before testing.
- [ ] Evaluate ADC input settling against the chosen converter’s acquisition window.

## Next artifacts

- Select the signal range and parts, then write a one-page requirements sheet.
- Save calculations, LTspice files, and KiCad source for the first revision.
- Add board photographs, measured plots, test setup, and revision notes as work occurs.

## Technical references

- [TI: Filtered non-inverting amplifier design](https://www.ti.com/lit/pdf/SBOA294)