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On designing coarse grain reconfigurable arrays to operate in weak inversionRoss, Dian Marie 17 December 2012 (has links)
Field Programmable Gate Arrays (FPGAs) support the reconfigurable computing paradigm by providing an integrated circuit hardware platform that facilitates
software like reconfigurability. The addition of an embedded microprocessor and peripherals to traditional FPGA Combinational Logic Blocks (CLBs) interleaved with
interconnections has effectively resulted in a programmable system on-chip. FPGAs
are used to support flexible implementations of Application Specific Integrated Circuit (ASIC) functions. Because FPGAs are reconfigurable, they often are used in
place of ASICs during the cicuit design process. FPGAs are also used when only a
small number of ICs are required: ASICs necessitate large manufacturing runs to be
economically viable; for smaller runs the use of FPGAs is an economic alternative.
Application domains of interest, such as intelligent guidance systems, medical
devices, and sensors, often require low power, inexpensive calculation of trance-
dental functions. COordinate Rotation DIgital Computer (CORDIC) is an iterative algorithm used to emmulate hardware expensive multipliers, such as Multiply/ACculmulate (MAC) units, with only shift and add operations. However, because CORDIC is a sequential algorithm, characterized as having the latency of a
serial multiplier, techniques that speed up computational performance have many
applications.To this end, three implementations of standard CORDIC, (i) unrolled hardwired,
(ii) unrolled programmable, and (iii) rolled programmable, were implemented on four
Xilinx FPGA families: Virtex-4, -5, and -6, and Spartan-6. Although hardwired
unrolled was found to have the greatest speed at the expense of no runtime flexibility,
and rolled programmable was found to have the greatest flexibility and lowest silicon
area consumption at the expense of the longest propagation delay, improvements to
CORDIC implementations were still sought.
Three parallelized CORDIC techniques, P-CORDIC, Flat-CORDIC, and
Para-CORDIC, were implemented on the same four FPGA families. P-CORDIC
and Flat-CORDIC, were shown to have the lowest latency under various conditions;
Para-CORDIC was found to perform well in deeply pipelined, high throughput circuits. Design rules for when to use standard versus precomputation CORDIC techniques are presented.
To address the low power requirements of many applications of interest, the Unfolded Multiplexor-LRB (UMUX-LRB), patent held by Sima, et al, was analyzed in
weak inversion across four transistor technology nodes (180nm, 130nm, 90nm, and
65nm). Previous was also expanded from strong inversion across 180nm, 130nm, and
90nm technology nodes to also include 65nm.
The UMUX-LRB interconnection network is based upon the Xilinx commercial
interconnection network. Therefore, this network (MUX-LRB), and another static
circuit technique, CMOS-Transmission Gates (CMOS-TG), were profiled across all
four technology nodes to provide a baseline of comparision. This analysis found
the UMUX-LRB to have the smallest and most balanced rising and falling edge
propagation delay, in addition to having the greatest reliability for temperature and
process variation. / Graduate
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