Amplitude Modulation–Demodulation System
Real-time AM signal chain with custom op-amp active filters, modeled in LT-SPICE then built
Designed and analyzed a complete Amplitude Modulation (AM) and demodulation signal chain. The architecture was modeled and verified in LT-SPICE to validate theoretical performance and signal integrity. Key signal-conditioning stages were transitioned to physical hardware — specifically custom 3rd-order active filters engineered from op-amps and built on a breadboard — to demonstrate practical implementation and noise rejection.
Modeled and simulated full AM modulation/demodulation pathways in LT-SPICE
Designed and constructed 3rd-order active filters using discrete op-amps
Validated physical circuit performance against theoretical SPICE models
The modulated signal
The AM waveform. I designed and analyzed a full amplitude-modulation and demodulation chain end to end, from carrier to recovered message.
Simulate first
The LT-SPICE model. I validated the whole signal path in simulation first — checking theoretical performance and signal integrity before touching a breadboard.
Demodulated output
Recovered output. The key analog stages — custom 3rd-order active filters built from op-amps — are what reject noise and pull the original signal back out.
Real audio through the chain
Recovering real audio through the chain was the satisfying part: theory, SPICE, and a breadboard all finally agreeing with each other.
On the bench
Measuring the physical circuit against the SPICE model on the oscilloscope to confirm the hardware matched the math.
Want the full story?
Happy to talk through any of the engineering decisions, trade-offs, or what broke along the way.