Study guide — what to focus on

This module is curated — the teaching is a top free series (linked in the card above); our job is to point you at the right things, make you prove it, and certify you. It builds on Analog Fundamentals, so you should already be comfortable with resistors, capacitors, op-amp basics and reading a voltage.

The plan

1. Watch the series (the card above — ALL ABOUT ELECTRONICS, Analog Filters, seven short lessons). You don't need to memorise every derivation — aim to understand the ideas below.
2. Focus on these — they're what the K-Check tests and what you'll use for real:
   • Filter types — low-pass, high-pass, band-pass and band-stop, and what each one keeps vs. rejects.
   • Cutoff frequency — the -3 dB (half-power) corner, and how filter order sets the roll-off (-20 dB/decade per pole).
   • Active vs. passive — why adding an op-amp gives you gain and buffering, not just an RC network.
   • Sallen-Key — the standard second-order active stage (one op-amp, two RC pairs) that realises a Butterworth or Chebyshev response.
   • Signal conditioning — amplifying a weak sensor signal cleanly. Watch the same channel's Instrumentation Amplifier video (companion link in the card) for high input impedance + common-mode rejection.
   • Getting into a microcontroller — the ADC & DAC companion series: Nyquist / anti-aliasing (sample at > 2× the highest frequency; low-pass first) and ADC resolution (2^bits levels).
3. Prove it in Forge (next section) — apply the filter → amplify → ADC chain to a real device.
4. Take the K-Check to earn your certificate.

Why this connects to building real products

Real sensors don't hand you a clean number — they hand you a small, noisy voltage. The analog signal chain is how you turn that into something a microcontroller can trust: filter out the noise and anything above half your sample rate, amplify the wanted part with a clean-gain stage, then let the ADC digitise it. Get any stage wrong — no anti-aliasing filter, too little gain, too few ADC bits — and the firmware downstream is reading garbage no code can fix. In Forge, when you describe a device that "reads a sensor," these are the stages that have to physically exist on the board between the sensor and the chip. Knowing them lets you read why a design is wired the way it is — and design the conditioning yourself.

Time to apply it. The series taught you the filter → amplify → digitise chain; now use it to design a real device.

Send the prompt below in Forge Design and watch where it places the filter (cleaning up the noise and blocking anything above half the sample rate) and the amplifier (lifting the small sensor signal) before the microcontroller's ADC reads it. As you read Forge's answer, trace the analog path end to end: where would an anti-aliasing low-pass sit, where does the gain stage go, and where does the signal finally become a number? That mapping — signal chain ↔ real parts — is the whole point.