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Team XOR. deSIGN PROPOSAL FOR DSP. 29 April 2010. Domenic Carr Jae Park Daniel Reyno. Sizing of Circuit ( V m ). Minimize WC Delay Most Important Metric Originally 2:1 Ratio 3 to 1.5 (in µm) Optimize P:N Ratio 2.33 to 1.5 (in µm) Also Reduces Area. AND/OR/NOP/PASS: CMOS or Pass?.
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Team XOR deSIGN PROPOSAL FOR DSP 29 April 2010 Domenic Carr Jae Park Daniel Reyno
Sizing of Circuit (Vm) • Minimize WC Delay • Most Important Metric • Originally 2:1 Ratio • 3 to 1.5 (in µm) • Optimize P:N Ratio • 2.33 to 1.5 (in µm) • Also Reduces Area
AND/OR/NOP/PASS: CMOS or Pass? • CMOS Logic • No Buffers/Inv Inputs • AND Gate: 14.49µm • OR Gate: 16.15µm • 16AND+16OR=490.24µm • Saves Area • Pass Gate Logic • Buffers (+7.66u) and Inverted Inputs (+3.83u) • AND Gate: 16.82u • OR Gate: 17.65u • 16AND+16OR=551.52µm
Mirror Adder Topology Utilizes Kill/Propagate/Generate property of bitwise addition for quick calculation of carry out bits.
Adder/Subtractor To include subtraction functionality, we simply augmented our base adder with extra hardware (17 2:1 MUXes and 9 inverters) to implement two’s complement subtraction.
Barrel Shifter • WC: Pass thru 1 NMOS • TX Gates Variation: • Larger Tapered Buffers • Buffer Regeneration • A only loads buffer • Total = 308.18u
Other Shifter Implementations • 4:1/2:1 MUX Variation • 4:1 MUX = 49.79 (includes buffering) • Total = 796.64u • TX Gate Variation • 16(2INV + TX) =(306.4u) • With Decoder (65.62u) • Total = 372.02u
Shifter Decoder (w/ and w/o PassA) • B1B0 loads 1 INV, 2 AND = 14.49u • Pass A (separately) • Total = 430.74u • PassA (w/ Shifter) • 8 3-input NANDs, 1 4-input OR, 3 inverters • Total = 465.08u
Gen1 MUX Technology Area of 16 Gen1 MUXes: 7,271 µm -3 Inverters -8 4-input AND gates -1 8-input OR gate
Gen2 MUX Technology Implemented Predecoding scheme (left) and simplified 8-input OR gate to series of 2-input NANDS and 2-input NORS (right)
Gen2 MUX Technology Gen2 MUX Technology had total area of 5,577.44 micrometers. The entire ALU would have had an area of 12,204.48 micrometers.
Gen3 MUX Technology 7 2:1 MUXes 6 Buffers
Gen3 MUX Technology Gen3 MUX Technology had total area of 2,022 micrometers. The entire ALU now had an area of 8,649 micrometers.
Multiplier Metric • Delay: 6.75 ns • Area: 8554.16 µm • Energy: 531 pJ/op
Function Enabler • Decoder that used control lines to determine which function should be powered by VDD • Motivations: • 128 possible operations occurring in parallel during any given cycle – Lots of wasted power • Desirable to have only the 16 relevant bits calculated
VDD Analysis • VDD = 2.5V • Delay: 18.95 ns • Area: 8649.28 um • Power: 125 pJ/op • Metric: • 3.88 * 10-28 [s2*m*J/op] • VDD = 4V • Delay: 10.05 ns • Area: 8649.28 um • Power: 389 pJ/op • Metric: • 3.71 * 10-28 [s2*m*J/op]
Metrics (VDD=5V) • Circuit (w/o MULT) • Delay: 8.83 ns • Area: 8649.28 um • Energy: 540 pJ/op • Total Metric: • 3.637 * 10-28 [s2*m*J]