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.
Entry 05 / PCB design
Sensor signal-conditioning PCB.
Define the signal. Then earn the measurement.
Planned · not startedPROPOSED ARCHITECTURE / ANALOG
- 01INPUTControlled signal
- 02GAINSelectable stage
- 03FILTERLow-pass pole
- 04OUTPUTADC interface
DEFINE → IMPLEMENT → VERIFY → DOCUMENT
01 / The work
Define the signal. Then earn the measurement.
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.
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.
Proposed validation / no tests run yet
How I plan to test it.
- 01
Review selected footprints and save ERC/DRC results, including explanations for intentional exceptions.
- 02
Measure DC transfer behavior across the specified range at every gain setting and check for clipping.
- 03
Sweep frequency below, through, and above the intended cutoff; compare measurements with simulation.
- 04
Set numerical pass limits from component tolerances and measurement uncertainty before testing.
- 05
Evaluate ADC input settling against the chosen converter’s acquisition window.
Technical references
TI: Filtered non-inverting amplifier design