ESD

2Analog Design Layout

2.1 Analog Design Layout Revisited

In analog design, unique design practices are used to improve the functional characteristics of analog circuitry [1–10]. In the electrostatic discharge (ESD) design synthesis of analog circuitry, the ESD design practices must be suitable and consistent with the needs and requirements of analog circuitry [11]. Fortunately, many of the analog design practices are aligned with ESD design practices [12–18]. In the analog design discipline, there are many design techniques to improve tolerance of analog circuits. Analog design techniques include the following:

• Local matching: Placement of elements close together for improved tolerance
• Global matching: Placement in the semiconductor die
• Thermal symmetry: Design symmetry

A key analog circuit design requirement is matching [1]. To avoid semiconductor process variations, matching is optimized by the local placement. Placement within the die location also is an analog concern due to mechanical stress effects. In analog design, there is a concern of the temperature field within the die and the effect of temperature distribution within the die.

Many of the analog design synthesis and practices are also good ESD design practices. The design practices of matching and design symmetry are also suitable practices for ESD design. But there are some design practices where a trade-off exists between the analog tolerance and ESD; this occurs when parasitic devices are formed between the ...