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Constraints of Mixed Signal Circuits in SoC
PROS CONS
• Cheap implementation of complex
signal processing tasks
• System-on-chip (SOC)
Small pcb footprint
• Fast time reference/clock
• Digitally assisted analog
• All advantages of digital
systems, e.g. robustness, noise
immunity, data storage,
reconfigurability, efficient highly
automated design and test
Stephan Henzler Mixed-Signal-Electronics 2012/13
• Need to build analog circuits in
digital process, i.e.
• Devices optimized for high
switching speed not for analog,
(e.g. small gm/gds)
• Transistors with high field
and short channel effects
µ(V G), V th(W,L,V DS,V BS), I gate, I DB
• Signal contamination due to digital
switching noise, e.g. cross talk,
supply noise substrate coupling
• several 100mA digital currents
• V analog signals
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