In today's SoC designs, both digital and analog parts of a circuit will be
implemented on one chip. Placement of the analog parts is an error prone
and time-consuming process. In analog placement, parasitic mismatch induced
by the layout will affect the circuit performance significantly.
One of the most important sources of mismatch is process gradient,
like oxide thickness, threshold voltage, resistor-layer thickness,
etc. These kinds of mismatch can be effectively suppressed by common
centroid layout, which refers to a layout style in which a set of
devices have a common center point. Devices will be
split into a number of smaller ones and placed with the
same center point. The devices can be arranged in one dimension or
in two dimensions. Two-dimensional arrangement is desired especially when
the number of devices is large, since close proximity is
desirable for better electrical properties such as parasitic
matching and thermal gradients.
Considerations of symmetry constraints during placement,
in which pairs of cells are required to be placed symmetrically
with respect to a horizontal or vertical axis,
can also help to reduce those errors.
Practical Placement and Routing Techniques for Analog Circuit Designs,
Linfu Xiao, Evangeline F.Y. Young, Xiaoyong He and K.P. Pun,
Proceedings IEEE International Conference on Computer-Aided Design, 2010.
iPRA (executables and data)
Analog Placement with Common Centroid Constraints,
Qiang Ma, Evangeline F.Y. Young and K.P. Pun,
Proceedings IEEE International Conference on Computer-Aided Design, 2007.
( executables and data - This version handles common
centroid, symmetry and other general placement constraints.)
Analog Placement with Symmetry and Other Placement Constraints,
Yiu-cheong Tam, Evangeline F.Y. Young and Chris Chu,
Proceedings IEEE International Conference on Computer-Aided Design, 2006.
(executables and data)
- Xiao Linfu (PhD)
- Cui Guxin (MPhil)
- Ma Qiang (MPhil)
- Tam Yiu Cheong (RA)
- RGC Earmarked Grant on "Placement with Analog Topological Constraints" (2008-11)