Differential pass transistor pulsed latchDifferential pass transistor pulsed latch Moo-Young Kim, Inhwa Jung, Young-Ho Kwak,

Chulwoo Kim

指導老師 : 魏凱城 老師

學 生 : 蕭荃泰

彰化師範大學積體電路設計研究所彰化師範大學積體電路設計研究所

OutlineOutline

• Abstract• Conventional flip-flops• Proposed flip-flop design• Simulation conditions and test bench• Simulation results• Conclusion

AbstractAbstract

• This paper describes the Differential Pass Transistor Pulsed Latch (DPTPL) which enhances D-Q delay and reduces power consumption using NMOS pass

transistors and feedback PMOS transistors.

• The power consumption of the proposed pulsed latch is reduced significantly due to the reduced clock load and smaller total transistor width compared to conventional differential flip-flops.

• The simulations were performed in a 0.13 um CMOS technology at 1.2V supply voltage with 1.25GHz clock frequency.

• In a recent high frequency microprocessor, the clocking system consumed 70% of the total chip power consumption.

• In the clocking system, 90% of the power is consumed by the flip-flops.

Conventional flip-flopsConventional flip-flops

• The Master-Slave Latch (MSL) is a good candidate for low power applications.

• Hybrid latch flip-flop (HLFF) and semi-dynamic flip-flop (SDFF) have small delay at the cost of power consumption.

• Sense amplifier-based flip-flops (SAFF) and modified sense amplifier-based flip-flops (MSAFF) as well as differential type flip-flops.

• The ep-SFF has the advantages of lower power consumption and small delay.

• The modified SDFF (MSDFF) is one of the fastest flip-flops.

Schematics of (a) explicit-pulsed hybrid static flip-flop, (b) pulsed-clockgenerator, and (c) pulsed generator timing diagram

Proposed flip-flop designProposed flip-flop design

Schematics of (a) differential pass transistor pulsed latch (DPTPL)and (b) pulsed clock generator

Simulation conditions and test benchSimulation conditions and test bench

• First, all flip-flops are simulated in a 0.13 um CMOS technology at 100◦C with 1.2V supply voltage and normal process corners. The operating clock frequency

in this simulation is 1.25GHz.

• For fair comparison of simulation results, all of the flip-flops are optimized to have minimum E×D with the same output load of 25fF.

• Secondly, for chip testing, Operating frequency in this simulation is 1GHz.

Power and delay measurement test bench for overall comparison

On-chip delay measurement block diagram

Layout of overall block diagram for chip test

Simulation resultsSimulation results

Signal waveforms of DPTPL

Delay comparison: conventional versus proposed flip-flops

Overall power comparison

General characteristics

ConclusionConclusion• DPTPL, utilizing the strong drivability of NMOS with positive f

eedback PMOS transistors, enables faster operation than their conventional counterparts.

• It also has an advantage of lower power consumption mainly due to simplicity and smaller clock load, and total gate width.

• DPTPL reduces E×D by 45.5% over ep-SFF, which have the best characteristics in our simulations among the convent

ional flip-flops.