8-bit SAR-ADC with offset calibration

This is a mixed-mode project featuring a 8-bit SAR-ADC, with offset calibration. The logic section is synthesized using the openlane digital flow.

SAR

The adc is composed of a top-plate sampled CDAC, with a capacitor array of mimimum sized MIM caps.

The comparator is a single-stage regenerative comparator, with a MOM array for trimming ADC offset.

Layout

The layout is created using magic as a pcell generator and drc checker, while the connection of the design is done using klayout.

Simulation

The simulation is carried out using ngspice using the mixed-mode xspice capabilities. The digital section is synthesized using yosys that can then be bridged to/from the analog section.

The Schematics are created using xschem, which also serves as the simulation framework.

The SAR schematic:

The simulation output can then be viewed in both analog and digital domain.

Digital waveforms displayed using GTKWave

Analog waveforms displayed using Gnuplot in interactive mode.