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Electronic Design

Field-Programmable Analog Array Delivers FPGA-Like Benefits

By combining programmable switched-capacitor op-amp cells with flexible on-chip configuration techniques and clocking resources, Anadyne Microelectronics has launched its first field-programmable analog array (FPAA). The AN10E40 comprises 20 configurable analog blocks (CABs) in a 4-by-5 matrix surrounded by programmable interconnects and I/O cells.

Around the array's periphery are 13 analog I/O cells that are preconfigured to function as buffers. Additionally, the AN10E40 includes an 8-bit programmable internal voltage reference and four programmable clocks with a maximum frequency of 1 MHz. Furthermore, it offers two uncommitted op amps.

The AN10E40 uses binary-weighted capacitor clusters. Each capacitor can take up to 256 different values. A flexible switching mechanism around the capacitor banks lets users create complex configurations, thus implementing a wide range of functions based on the op amps.

The circuit's configuration is held in on-chip SRAM. This SRAM is initialized on power-up via an off-chip serial EPROM or the microprocessor interface. An accompanying CAD tool, the AnadyneDesigner, supports the FPAA. Using its library of 50 parameterizable analog functions, engineers can create custom designs on the computer screen.

For example, they can design signal conditioning for multichannel, signal-processing functions such as proportional integral derivative (PID) control or other complex circuits. Upon satisfaction, users can download this graphical representation onto the chip by clicking a button.

"This design software, with its library, allows inexperienced users to build systems without needing to know the underlying complexities of switched-capacitor techniques," says Mike Kay, Anadyne's president. "In terms of field programmability, the FPAA represents a new direction for the analog circuit designer. Like FPGAs," he adds, "it permits reconfiguration during assembly or on-the-fly in the field."

Interestingly, Anadyne isn't the only visionary. Late last year, Lattice Semiconductor Corp. of Hillsboro, Calif., entered the arena with its in-system programmable analog circuit, the ispPAC (see "Reconfigurable Analog ICs Herald An Era Of In-System Programmability," Electronic Design, Nov. 8, 1999, p. 72). Meanwhile, a startup company also is currently leveraging programmable technologies to enter this field. No details were available at press time, though.

The Anadyne chip operates from a 5-V supply. It comes in an 80-pin QFP. In production quantities, the AN10E40 costs $15.50 each. A development board also is available for under $500.

Anadyne Microelectronics, 21615 Stevens Creek Blvd., Cupertino, CA 95014-2350; (408) 996-2091; fax (408) 996-2093;

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