skywater-pdk/docs/rules/device-details/res_high/index.rst

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P+ poly precision resistors
---------------------------
Spice Model Information
~~~~~~~~~~~~~~~~~~~~~~~
- Cell Name: :cell:`res_high_po_XpXX`, :cell:`sky130_fd_pr__res_high_po`
- Model Type: subcircuit
Operating ranges where SPICE models are valid
- \|V\ :sub:`r0` V\ :sub:`r1`\ \| = 0 to 5.0V
- Currents up to 500 µA/µm of width (preferred use ≤ 100 µA/µm)
Details
~~~~~~~
The resistors have 5 different fixed widths, plus a variable W/L option.
- 0.35 (0p35)
- 0.69 (0p69)
- 1.41 (1p41)
- 2.85 (2p83)
- 5.73 (5p73)
They are modeled as subcircuits, using a conventional resistor model combined with the capacitance under the resistor, as well as matching parameters and temperature coefficients. The fixed-width resistors may only be used in the above configurations. Each resistor end is contacted using a slot licon. Length is variable and measured between the front ends of the slot licons.
The fixed-width resistors are modeled using the equation
*R\ :sub:`0`* = head/tail resistance [Ω] (dominated by the slot licons)
*R\ :sub:`1`* = body resistance [Ω/µm] = R\ :sub:`SH`/W
A top-down schematic drawing of the precision resistor is shown below.
|res_high_po|
In addition to the R\ :sub:`0` and R\ :sub:`1` values, several fixed-value resistors are measured at e-test, as shown in the table below:
.. include:: res_high-table0.rst
More details on the use of the precision resistors, and their models, are in the document ***SKY130 process Family Device Models*** (002-21997), which can be obtained from SkyWater upon request.
The symbols for the 300 ohm/sq precision resistors are shown below:
|symbol-res_high_po_0p35| |symbol-res_high_po_0p69|
:model:`sky130_fd_pr__res_high_po_0p35` :model:`sky130_fd_pr__res_high_po_0p69`
|symbol-res_high_po_1p41| |symbol-res_high_po_2p85|
:model:`sky130_fd_pr__res_high_po_1p41` :model:`sky130_fd_pr__res_high_po_2p85`
|symbol-res_high_po_5p73|
:model:`sky130_fd_pr__res_high_po_5p73`
A generic version of the poly resistor is also available, which permits user inputs for W and L, and connections in series or parallel.
|symbol-res_high_po|
.. |res_high_po| image:: res_high_po.svg
.. |symbol-res_high_po_0p35| image:: symbol-res_high_po_0p35.svg
.. |symbol-res_high_po_0p69| image:: symbol-res_high_po_0p69.svg
.. |symbol-res_high_po_1p41| image:: symbol-res_high_po_1p41.svg
.. |symbol-res_high_po_2p85| image:: symbol-res_high_po_2p85.svg
.. |symbol-res_high_po_5p73| image:: symbol-res_high_po_5p73.svg
.. |symbol-res_high_po| image:: symbol-res_high_po.svg