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This is an old version of the compendium, written Nov. 27, 2017, 2:15 p.m. Changes made in this revision were made by larshb. View rendered version.
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TFE01: Low power digital design

# Introduction ## Disclaimer This compendium is a work in progress and needs review and possibly restructuring and citations. The current structure is based on the ordering and naming of lectures from the 2017 semester. ## Specialization course This subject is part of the [Design of Digital Systems, Specialization Course (TFE4525)](https://www.wikipendium.no/TFE4525_Design_of_Digital_Systems_Specialization_Course). # Fundamentals ## Power dissipation Power dissipation in CMOS circuits are typically divided into three components, namely _static power_, _dynamic power_ and _short-circuit power_. ### Static power dissipation Mostly the power dissipated through leakage currents. $$ P_s = V_{DD} \times I_D, $$ where $V_{DD}$ is the supply voltage and $I_D$ is the leakage current. ### Dynamic power dissipation Power from switching logic by charging and discharging in capacitors. $$ P_d = \alpha f_{CLK} C_L V_{DD}^2, $$ where $\alpha$ is the activity factor, $f_{CLK}$ is the clock frequency, $C_L$ is the swithing load capacitance, and $V_{DD}$ is the supply voltage. ### Short-circuit power dissipation Caused by transients in switching in the window when p-channel and n-channel of eg. and inverter connects the supply voltage to ground. This power is arguably related to the activity factor of the circuit and hence a part of the dynamic power dissipation. ## Delay, power and energy
Tightly intertwined in CMOS VLSI. Can be illustrated by theoretically adjusting factors in the above equations. By for instance lowering the frequency of a system you will obtain a lower dynamic power, however since power is just a measure of energy per time unit the total energy to perform a task in the same amount of clock cycles may change due to the circuits static power dissipation and glitches etc.
# Ultra low voltage and low power circuit design techniques ... # Razor flip-flops ... # HDL techniques for low power design ... # Brain-inspired chips for large data sets ... # Ultra-low power wireless microcontroller design ... # Energy scavenging ... # Low power FPGAs ... # Moore's law and technology scaling ... # Cloud computing ...
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