Generator Architecture

The automatic generator is organized as a reuse hierarchy rather than as a collection of independent layout scripts.

Complex analog modules reuse lower-level physical constructions and add only the placement and routing policies required by their circuit topology.

Reuse Hierarchy

Generated Module Examples

MOS-Based Modules

The MOS-based generator hierarchy reuses the common device primitive through single-device, interdigitated, common-centroid, and compound structures.

Single MOS. Reusable device construction and local terminal access.

Simple current mirror. Shared-diffusion interdigitation with dummies, local diode connection, and gate sharing.

Differential pair. Common-centroid placement with local dummies and pair-specific access.

Cascode current mirror. Compound structure assembled from reusable matched rows.

Wide-swing current mirror. Shared and source-isolated row structures with topology-specific routing.

Cascoded differential pair. A common-centroid input array combined with a split-diffusion cascode row.

Passive Module

The capacitor generator forms a separate passive branch. It uses a MIM capacitor primitive rather than the MOS-device construction, while exporting the same type of module interface for top-level integration.

MIM capacitor. Simplified passive module with explicit plate access for top-level integration.

Internal Closure

Local analog structure remains inside the generated child cell.

The generator is responsible for:

• device-finger ordering;
• dummy-device insertion;
• local gate and drain/source buses;
• diode connections;
• internal stack-node connections;
• topology-specific local routing;
• local guard-ring construction where required.

The top-level flow does not reconstruct these structures.

Instead, each module exports a compact interface describing the information needed by downstream physical-design stages.

Public Generator Coverage

The prototype includes selected generator families covering:

• single MOS devices;
• two- and three-branch simple current mirrors;
• two- and three-branch cascode current mirrors;
• Wilson current mirrors;
• improved-Wilson current mirrors;
• wide-swing current mirrors;
• differential pairs;
• cascoded differential pairs;
• MIM capacitors.

The generator library is a prototype rather than a complete layout synthesis library for arbitrary analog topologies.

Why Reuse Matters

The central implementation idea is not merely that several circuit topologies can be drawn automatically.

The same low-level layout construction is reused across different families. The family-specific behaviour is concentrated in:

• row organization;
• diffusion-sharing policy;
• dummy policy;
• relative placement;
• local buses;
• guard-ring policy;
• topology-specific routing.

This reduces duplicated layout logic and keeps related module families physically consistent.