Design and Integration of Multiple Open-Source Analog Circuits Fabricated in SKY130 Technology within Silicluster v2
Abstract
This work presents the design and integration of multiple analog circuits using an open-source design flow and fabricated in SKY130 CMOS technology within the Silicluster v2 system. The portfolio includes four low-pass filters with cutoff frequencies of 2.43 kHz, 24.3 kHz, 243 kHz, and 2.43 MHz; two ring oscillators of 50 MHz and 100 MHz; a buffer built with discrete transistors; an inverter with dummy devices to improve matching; and a two-stage operational amplifier. The chip also incorporates an analog multiplexer that enables individual selection and evaluation of each block through a shared input–output interface, as well as an 8-bit ADC and DAC that facilitate mixed-signal integration. The objective is to demonstrate the feasibility of designing and integrating compact analog modules using only open-source tools and PDKs, validating their functionality through simulations and physical verification in the SKY130 process.
Full text
Design and Integration of Multiple Open-Source Analog Circuits Fabricated in SKY130 Technology within Silicluster v2. Uriel Jaramillo-Toral, Héctor Emmanuel Muñoz Zapata, Emilio Issac Baungarten, Susana Ortega-Cisneros Center for Research and Advanced Studies (CINVESTAV) Presented by: Av. del Bosque 1145, El Bajío, 45017 Zapopan, Jal. Méx. Design and Integration of Multiple Open-Source Analog Circuits Fabricated in SKY130 Technology within Silicluster v2.
Introduction •This work integrates several compact analog modules inside the Silicluster v2 chip, using a completely open-source design flow in SKY130 technology. •It includes filters, oscillators, a buffer, an inverter, and an operational amplifier, as well as mixedsignal blocks for their characterization. •It demonstrates that it is possible to design and fabricate multiple analog modules on a single chip using only open-source tools, meeting physical-design rules and achieving consistent results. 2/22 Design and Integration of Multiple Open-Source Analog Circuits Fabricated in SKY130 Technology within Silicluster v2.
What is Silicluster? 3/22 Silicluster V2 •Silicluster is a circuit-integration platform that allows grouping dozens of independent modules into a single chip. •It uses an internal multiplexing architecture that selects any module and connects it to common input/output pins, avoiding the need to fabricate a separate chip for each design. •It was created to enable testing, characterization, and rapid prototyping using open-source tools and PDKs. Design and Integration of Multiple Open-Source Analog Circuits Fabricated in SKY130 Technology within Silicluster v2.
Silicluster Versions 4/22 •Silicluster has gone through four versions. The Beta version integrated 64 digital modules, while version 1 increased the capacity to 256. •Later, a test version was developed using Minimal Fab technology. •Finally, version 2 kept the 256 modules but added the capability to include up to 48 analog or mixed-signal blocks, enabling more complete characterization. Design and Integration of Multiple Open-Source Analog Circuits Fabricated in SKY130 Technology within Silicluster v2.
International Recognition of Silicluster 5/22 Silicluster has gained international visibility with three IEEE 2025 conference publications: APCCAS in South Korea, VLSI-SoC in Chile, and LAEDC in Mexico, establishing it as a notable platform for integrated-circuit design Design and Integration of Multiple Open-Source Analog Circuits Fabricated in SKY130 Technology within Silicluster v2.
Analog Circuits Designed for Silicluster V2 6 Design and Integration of Multiple Open-Source Analog Circuits Fabricated in SKY130 Technology within Silicluster v2. •Low-pass filters •Ring oscillators •Buffer •Inverter •Operational amplifier •Analog demultiplexer
RC Low-Pass Filters 7/22 •The four low-pass filters were implemented using eight parallel capacitors while maintaining the same total capacitance. •Different cutoff frequencies were obtained by modifying only the resistance, achieving −3 dB points from a few kHz up to several MHz. •Simulations confirmed the expected behavior, and the layout showed a compact integration compatible with SKY130. Design and Integration of Multiple Open-Source Analog Circuits Fabricated in SKY130 Technology within Silicluster v2.
Low-Pass Filters 8/22 Layouts AC Analysis Design and Integration of Multiple Open-Source Analog Circuits Fabricated in SKY130 Technology within Silicluster v2.
Ring Oscillators 9/22 Two ring oscillators were implemented at 50 MHz and 100 MHz using chains of inverters. Simulations confirmed stable oscillation, and the layout showed a symmetric distribution suitable for SKY130. These blocks enable testing of internal high-frequency signals in an open-source environment. Design and Integration of Multiple Open-Source Analog Circuits Fabricated in SKY130 Technology within Silicluster v2.
Design and Integration of Multiple Open-Source Analog Circuits Fabricated in SKY130 Technology within Silicluster v2. 16 Silicluster also includes digital and mixed-signal designs such as: •A 4-bit Flash Analog-to-Digital Converter (ADC) and an 8-bit Successive Approximation Register (SAR) ADC. •An 8-bit R-2R Digital-to-Analog Converter (DAC). •16-bit counters. •Neural networks. •State Machines. •Encryptors, among others.
Conclusion 17/22 •This work demonstrated that it is possible to integrate several compact analog modules into a single chip using only opensource tools and the SKY130 technology. • The filters, oscillators, buffer, inverter, and operational amplifier were implemented and validated through simulation and layout within Silicluster v2, confirming stability and compliance with physical-design rules. •These results show the maturity of the open-source ecosystem for analog design and enable the integration of more complex circuits in future versions of the project. Design and Integration of Multiple Open-Source Analog Circuits Fabricated in SKY130 Technology within Silicluster v2.
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