| Varactors |
| --------- |
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| Spice Model Information |
| ~~~~~~~~~~~~~~~~~~~~~~~ |
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| - Cell Name: :cell:`sky130_fd_pr_base__capbn_b` |
| - Model Name: :model:`sky130_fd_pr_base__xcnwvc`, :model:`sky130_fd_pr_base__xcnwvc2` |
| - Model Type: subcircuit |
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| Operating Voltages where SPICE models are valid |
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| - \|V\ :sub:`0` – V\ :sub:`1`\ \| = 0 to 2.0V |
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| Details |
| ~~~~~~~ |
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| The following devices are available; they are subcircuits with the N-well to P-substrate diodes built into the model: |
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| - xcnwvc—low VT PMOS device option |
| - xcnwvc2—high VT PMOS device option |
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| The varactors are used as tunable capacitors, major e-test parameters are listed below. Further details on the device models and their usage are in the SKY130 process Family Spice Models (002-21997), which can be obtained from SkyWater upon request. |
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| .. include:: varactors-table0.rst |
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| There is no equivalent varactor for 5V operation. The NHV or PHV devices should be connected as capacitors for use at 5V. |
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| The symbols for the varactors are shown below: |
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| |symbol-varactors-a| |symbol-varactors-b| |
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| The cross-section of the varactor is shown below: |
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| |cross-section-varactors| |
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| .. |symbol-varactors-a| image:: symbol-varactors-a.svg |
| .. |symbol-varactors-b| image:: symbol-varactors-b.svg |
| .. |cross-section-varactors| image:: cross-section-varactors.svg |
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