Voltage Threshold Optimization: Balancing Leakage and Performance in Integrated Circuits

Abstract

This body of work covers the utility of the development of a tool for automatically
configuring the transistors in an existing netlist, according to a set of specifications.
By swapping out transistors for transistors with other Voltage Thresholds it can
achieve target speeds with acceptable accuracy and reduce the static power consumption of a circuit. To make this process feasible, the tool uses approximations
to predict what configurations would meet its constraints.
In testing, it was found that the tool could affect the leakage by up to a factor
of 246 and frequency by a factor of 2.14. The tool could predict leakage with
high accuracy, while the accuracy of frequency estimations was dependent on the
architecture in question. As the tool has been iterated on, it has become more
reliable in that regard as well.
Using results from the tool it is possible to tell how big an impact Voltage
Threshold has on the performance of the circuit varies wildly with size and architecture. Depending on the technology in question, a lot of power can be saved
with relatively little effort.

Popular Abstract

Integrated circuits are paramount in a vast range of everyday devices, in virtually
anything that has a power cord or runs on batteries nowadays. They control various components on the devices to enable sophisticated functionality, after specific
instructions. For basic functionality, the circuit can be painstakingly designed in
a smart way to achieve it.
But if those circuits are going to direct tasks that are more complicated than
the very simplest, they need an efficient and modular way of storing the instructions. The industry standard is using an integrated memory.
A customer will want the most efficient memory of sufficient size for their purpose, to save on manufacturing costs, and to make a more energy-efficient product.
When using an off-the-shelf memory, this means they have to find a memory that
meets their minimum requirements for speed. In all likelihood, the memory will
be faster than required, but that is of no benefit to the device. That extra speed
will still come at the cost of power consumption.
For this reason, creating designs for integrated memories after precise specifications can be valuable to customers since they can now have access to memories
with minimal wasted capacity. However, creating designs is a lengthy process. In
this project, an attempt was made to create a means of slightly altering existing
designs to fit other constraints, possibly removing the need for new designs if the
specs are sufficiently close to existing designs.
To accomplish this, a tool was programmed. The tool automatically adjusts
one of the primary components of the memory, the transistors. Swapping transistors in a design is a lesser effort, as different transistor types come in the same
size. The challenge is in how many transistors there are, but for an automatic tool
that is of little consequence.

• author: Raguz, Filip and Qvint, Joel
• supervisor: Jonas Skeppstedt
• organization: Department of Electrical and Information Technology
• course: EITM01 20241
• year: 2024
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: optimization, transistor, voltage threshold, leakage, speed, power, performance, frequency, verilog-a, sram, memory
• report number: LU/LTH-EIT 2024-990
• language: English
• id: 9165795
• date added to LUP: 2024-06-19 10:35:00
• date last changed: 2024-06-19 10:35:00