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  1. de2a343 final gds oasis by Jeff DiCorpo · 1 year, 1 month ago main
  2. 9f9ce67 Another try to fix MPW precheck errors. by Luis Henrique Rodovalho · 1 year, 1 month ago
  3. 195c5cd Update README.md by Luís Henrique Rodovalho · 1 year, 1 month ago
  4. e9c12a3 VREF output short circuit corrected. by Luis Henrique Rodovalho · 1 year, 1 month ago
  5. 2d95693 Merge branch 'main' of https://github.com/lhrodovalho/sky130sbcs by Luis Henrique Rodovalho · 1 year, 1 month ago

A resistorless self-biased current source intended to be integrated in the efabless MPW4.

Table of contents


Summary

Most, if not all, analog integrated circuits are limited by their reference voltage and current sources. This project aims to provide a current source reference with the lowest power consumption and supply voltage possible for this technology.

A conventional gm-constant self-biased current source uses integrated resistors, which can be very large for very low current consumption. Besides that, the integrated resistor creates another independent variable of process variability in addition to the active components. A CMOS only current source process variability is a function of only the active components.

The proposed self-biased current source is based on the topology introduced by Francisco Serra-Graells and Jose Luis Huertas in “Sub-1-V CMOS proportional-to-absolute temperature references” [1], with the addition of high-swing cascode and series-parallel current mirrors [2].

Target Performance Summary

Specifications-
VDD1.0-1.8 V
Total current3.60 μA
Output current0.27 μA
Temperature stability0.5 %/V
Supply stability1160 ppm/°C
Area100 x 60 μm²

Description

Schematics and Layouts


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Self-biased current source circuit diagram

Simulation Results

TT corner

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Status and Issues

  • There are no schematics. All simulations are from extracted netlists.
  • This project also contains a CMOS only voltage reference based on the main current-source, but there is no documentation available.
  • There is a second version of the same current source, but using high-voltage transistors. Only the layer types were replaced.
  • Documentation is extremely incomplete.

Team members

Ph.D. Luís Henrique Rodovalho (Rodovalho) | luishenriquerodovalho@gmail.com |

References

[1] Serra-Graells, Francisco, and Jose Luis Huertas. “Sub-1-V CMOS proportional-to-absolute temperature references.” IEEE Journal of Solid-State Circuits 38.1 (2003): 84-88.

[2] Arnaud, Alfredo, Rafaella Fiorelli, and Carlos Galup-Montoro. “Nanowatt, sub-nS OTAs, with sub-10-mV input offset, using series-parallel current mirrors.” IEEE Journal of Solid-State Circuits 41.9 (2006): 2009-2018.