Modified the parameter check routine for FETs and resistors in the
magic device generator script for sky130 to not attempt to enforce
the maximum array size to satisfy the tap spacing rule. The first
problem was that the estimated clearance for each device was set
too high, but more generally the problem is that the maximum size
can only be estimated. Therefore the response was changed from
enforcement to a printed warning.
diff --git a/VERSION b/VERSION
index c2126aa..1be2b39 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.0.475
+1.0.476
diff --git a/sky130/magic/sky130.tcl b/sky130/magic/sky130.tcl
index 48cec26..31051a5 100644
--- a/sky130/magic/sky130.tcl
+++ b/sky130/magic/sky130.tcl
@@ -4842,8 +4842,8 @@
}
}
- # Diffusion resistors must satisfy diffusion-to-tap spacing of 20um.
- # Therefore the maximum of guard ring width or height cannot exceed 40um.
+ # Diffusion resistors must satisfy diffusion-to-tap spacing of 15um.
+ # Therefore the maximum of guard ring width or height cannot exceed 30um.
# If in violation, reduce counts first, as these are easiest to recover
# by duplicating the device and overlapping the wells.
if {$device == "rdn" || $device == "rdp"} {
@@ -4855,16 +4855,16 @@
if {[expr min($xext, $yext)] > 40.0} {
if {$yext > 40.0 && $m > 1} {
incr m -1
- } elseif {$xext > 40.0 && $nx > 1} {
+ } elseif {$xext > 30.0 && $nx > 1} {
incr nx -1
- } elseif {$yext > 40.0} {
- set l 36.6
- puts -nonewline stderr "Diffusion resistor length must be < 36.6 um"
+ } elseif {$yext > 30.0} {
+ set l 29
+ puts -nonewline stderr "Diffusion resistor length must be < 29 um"
puts stderr " to avoid tap spacing violation."
dict set parameters l $l
- } elseif {$xext > 40.0} {
- set w 38.2
- puts -nonewline stderr "Diffusion resistor width must be < 38.2 um"
+ } elseif {$xext > 30.0} {
+ set w 29
+ puts -nonewline stderr "Diffusion resistor width must be < 29 um"
puts stderr " to avoid tap spacing violation."
dict set parameters w $w
}
@@ -4873,12 +4873,12 @@
}
}
if {$m != $origm} {
- puts stderr "Y repeat reduced to prevent tap distance violation"
- dict set parameters m $m
+ puts stderr "Warning: Fingers may need to be reduced to prevent tap distance violation"
+ # dict set parameters m $m
}
if {$nx != $orignx} {
- puts stderr "X repeat reduced to prevent tap distance violation"
- dict set parameters nx $nx
+ puts stderr "Warning: M may need to be reduced to prevent tap distance violation"
+ # dict set parameters nx $nx
}
}
sky130::compute_ltot $parameters
@@ -7003,28 +7003,34 @@
dict set parameters viagl 100
}
- # Values must satisfy diffusion-to-tap spacing of 20um.
- # Therefore the maximum of guard ring width or height cannot exceed 40um.
- # If in violation, reduce counts first, as these are easiest to recover
- # by duplicating the device and overlapping the wells.
+ # Values must satisfy diffusion-to-tap spacing of 15um.
+ # Therefore the maximum of guard ring width or height cannot exceed 30um.
+ # This requires detailed knowledge of the layout, so can only be estimated
+ # here. Since the estimate may be off, do not enforce the rule but just
+ # generate a warning.
+
+ # "clearance" is an estimation of the amount of space taken up by the
+ # gate or source/drain contacts.
+ set clearance 1.0
+
set origm $m
set orignf $nf
while true {
- set yext [expr ($w + 3.0) * $m]
- set xext [expr ($l + 1.0) * $nf + 1.1]
- if {[expr min($xext, $yext)] > 40.0} {
- if {$yext > 40.0 && $m > 1} {
+ set yext [expr ($w + $clearance) * $m + $clearance]
+ set xext [expr ($l + $clearance) * $nf + $clearance]
+ if {[expr min($xext, $yext)] > 30.0} {
+ if {$yext > 30.0 && $m > 1} {
incr m -1
- } elseif {$xext > 40.0 && $nf > 1} {
+ } elseif {$xext > 30.0 && $nf > 1} {
incr nf -1
- } elseif {$yext > 40.0} {
- set w 37
- puts -nonewline stderr "Transistor width must be < 37 um"
+ } elseif {$yext > 30.0} {
+ set w 29
+ puts -nonewline stderr "Transistor width must be < 29 um"
puts stderr " to avoid tap spacing violation."
dict set parameters w $w
- } elseif {$xext > 40.0} {
- set l 37.9
- puts -nonewline stderr "Transistor length must be < 37.9 um"
+ } elseif {$xext > 30.0} {
+ set l 29
+ puts -nonewline stderr "Transistor length must be < 29 um"
puts stderr " to avoid tap spacing violation."
dict set parameters l $l
}
@@ -7033,12 +7039,12 @@
}
}
if {$m != $origm} {
- puts stderr "Y repeat reduced to prevent tap distance violation"
- dict set parameters m $m
+ puts stderr "Warning: M may need to be reduced to prevent tap distance violation"
+ # dict set parameters m $m
}
if {$nf != $orignf} {
- puts stderr "X repeat reduced to prevent tap distance violation"
- dict set parameters nf $nf
+ puts stderr "Warning: Fingers may need to be reduced to prevent tap distance violation"
+ # dict set parameters nf $nf
}
# Used by varactor only
