A field programmable analog array for switched capacitor filters

Abstract

The advantage of using a semi-custom design approach over a fully custom design approach are a faster turnaround of circuit design, ease of use for the inexperienced engineer, and lower production costs. A semi-custom design approach, however, has a heavily constrained layout and thus is not optimum for high performance circuits. Analog arrays are a particular type of semi-custom circuit which are currently being used in industry. The objective of this work is to develop a design methodology for designing a field programmable analog array (FPAA). This work is meant to be used in systems that require filtering in the audio bandwidth ( 20 Hz-20 kHz) and thus is limited in its direct application. The first process in developing the FPAA is to determine an architecture or floor plan for the layout of the FPAA. This involves the design of the active ceus (ie. programmable opamp), a programmable capacitor bank, the switches used in the SC filter synthesis, and the routing interconnections. A second objective of this work is to study and minimize the effects of the programmable switch parasitics on circuit performance, and overall system performance. A final objective of this work is to develop CAD tools in order to design and use the FPAA.