All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
2009 IEEE International Symposium on Circuits and Systems, 2009
Efficient power modeling of a generic class of digital circuits is crucial to the analysis and de... more Efficient power modeling of a generic class of digital circuits is crucial to the analysis and development of optimization algorithms of power efficient design. This paper proposes a new switching power index model for the power analysis of multiplier-block based FIR filter. Unlike the existing glitch path count (GPC) and glitch path score (GPS), the proposed power index (PI) model takes into account correlated input switching activity propagations of full adders within and across adders of different widths, as well as the variation of load capacitances due to sharing of adders in reduced adder graph. Dynamic power simulations of several benchmark filters in an ASIC design flow show that this PI measure is more closely correlated with the actual dynamic power dissipation than the existing GPC and GPS models.
2013 IEEE International Symposium on Circuits and Systems (ISCAS2013), 2013
ABSTRACT This paper introduces the notion of channel splitting to augment the scaling of microcha... more ABSTRACT This paper introduces the notion of channel splitting to augment the scaling of microchannels for a balanced microflu-idic cooling of 3DIC. The idea is to place appropriate number of channel splitters along various sections of microchannels to reduce the convective resistances at potential hotspots. The increases in pressure drops due to channel splitting are then redistributed by scaling the channel widths to match the coolant flowrates with the power distribution, which is usually nonuniform in practice. Unlike the existing techniques, this thermal balancing method requires no extra pump or valve. Only the customization of etching masks is needed for the deposition of silicon splitters and different sizes of microchannels. Experiment on a 4-layer multicore 3DIC stack shows that the proposed microchannel design technique can effectively reduce both the maximum temperature and thermal gradient in the 3D circuit.
2010 IEEE International 3D Systems Integration Conference (3DIC), 2010
This paper presents a cyber-physical (real-time sensepredict-adjust) thermal management for 3D mu... more This paper presents a cyber-physical (real-time sensepredict-adjust) thermal management for 3D multi-core system by micro-fluidic cooling. Auto Regressive (AR) model is used to predict future workload and the prediction is furnished by Kalman filtering to get rid of noises due to system variation. A thermal model is developed to sense thermal behaviour of the 3D system including micro-fluidic channels and estimate future thermal demand. The use of fine-grained, or non-uniform, flowrate control with channel clustering is then incorporated to adjust flow-rates based on the predicted future thermal demand in a real-time fashion. Experiment results show that under this cyber-physical scheme, the temperature of 3D multi-core cacheprocessor system is well maintained below threshold and a more even temperature distribution is achieved with lower fluid-pump power or total flow-rate overhead. For example, the total flowrate has a significant reduction of 72.1% under the fine-grained flow rate control 1 .
2013 18th Asia and South Pacific Design Automation Conference (ASP-DAC), 2013
This paper presents a fast and accurate steady state thermal simulator for heatsink and microflui... more This paper presents a fast and accurate steady state thermal simulator for heatsink and microfluid-cooled 3D-ICs. This model considers the thermal effect of TSVs at finegranularity by calculating the anisotropic equivalent thermal conductances of a solid grid cell if TSVs are inserted. Entrance effect of microchannels is also investigated for accurate modeling of microfluidic cooling. The proposed thermal simulator is verified against commercial multiphysics solver COMSOL and compared with Hotspot and 3D-ICE. Simulation results shows that for heatsink cooling, the proposed simulator is as accurate as Hotspot but runs much faster at moderate granularity. For microfluidic cooling, our proposed simulator is much more accurate than 3D-ICE in its estimation of steady state temperature and thermal distribution.
ASP Journal of Low Power Electronics (JOLPE), 2011
Existing three-dimensional (3D) integration of multi-core processor-cache system is confronted wi... more Existing three-dimensional (3D) integration of multi-core processor-cache system is confronted with the problem of die thermal run-away hazard. This teething problem is addressed by a real-time demand-based thermal management with non-uniform microfluidic cooling in this paper. A novel runtime temperature management is implemented to predict the real-time temperature demand based on software-sensing with prediction-and-correction. A 3D thermal model is developed to cater the real-time microfluidic thermal dynamics. An autoregressive (AR) prediction with correction is implemented by Kalman filtering to predict and correct the runtime power, which is further used to calculate the future temperature demand. With this software-sensing approach, thermal management can be performed in a cyber-physical fashion with real-time sensing, prediction-and-correction and fine-grained control. Compared to the existing works using on-chip temperature sensors, our closed-loop controller with software-sensing avoids the cost of sensor implementation and deployment. Our work analyzes and predicts the fine-grained temperature profile of multi-core processorcache system. It enables a number of microfluidic channels to be adjusted adaptively with different flow-rates to control the system temperature proactively as opposed to the static control with a uniform flow-rate for microfluidic channels. With the proposed cyber-physical temperature management scheme, it is shown that the temperature of multi-core system is suppressed below an acceptable thermal threshold. In fact, the fine-grained flow-rate control also achieves a more even temperature distribution and saves up to 72.1% of total flow-rate compared with uniform flow-rate controls.
Heat removal problem has been a bane of three dimensional integrated circuits (3DICs). Comparing ... more Heat removal problem has been a bane of three dimensional integrated circuits (3DICs). Comparing with other passive cooling techniques, microfluidic cooling appears to be an ideal cooling solution due to its high thermal conductivity and scalability. Without regarding to the fact of non-uniform power distribution of integrated circuits, existing microfluidic cooling with uniform cooling effort incurs large thermal gradient and wastes pump power. This can be avoided by the customized non-uniform cooling scheme proposed in this paper. The microfluidic channels are divided into clusters of relatively homogeneous power distribution and an appropriate flow rate setting is applied to each cluster based on the total flow rate and the maximum allowable temperature of the 3DIC. This paper proposes an efficient clustering algorithm to guide the division of microchannels into clusters and the allocation of cooling resources to each cluster in order to achieve an effective microfluidic cooling with minimal total flow rate. A compact steady state thermal simulator has been developed and verified. Supported by this fast and accurate thermal model, the proposed cooling method and clustering algorithm have been applied to a 3D multi-core testbench for simulation. Compared to the uniform flow rate cooling, the maximum temperature and thermal gradient were reduced under the same total flow rate settings. On the other hand, for a specific peak temperature constraint, up to 21.8% saving in total flow rate with moderate thermal gradients is achieved by the proposed clustered microfluidic cooling. been a problem for 2D large scale integrations as technology node scales and clock frequency increases , the stacking of circuits in 3DIC simultaneously increases power density and junction-to-ambient thermal resistances, making the circuits even more vulnerable to thermal induced hazards. Effective and efficient cooling techniques are thus needed to manage the thermal condition of 3D chips.
All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
2009 IEEE International Symposium on Circuits and Systems, 2009
Efficient power modeling of a generic class of digital circuits is crucial to the analysis and de... more Efficient power modeling of a generic class of digital circuits is crucial to the analysis and development of optimization algorithms of power efficient design. This paper proposes a new switching power index model for the power analysis of multiplier-block based FIR filter. Unlike the existing glitch path count (GPC) and glitch path score (GPS), the proposed power index (PI) model takes into account correlated input switching activity propagations of full adders within and across adders of different widths, as well as the variation of load capacitances due to sharing of adders in reduced adder graph. Dynamic power simulations of several benchmark filters in an ASIC design flow show that this PI measure is more closely correlated with the actual dynamic power dissipation than the existing GPC and GPS models.
2013 IEEE International Symposium on Circuits and Systems (ISCAS2013), 2013
ABSTRACT This paper introduces the notion of channel splitting to augment the scaling of microcha... more ABSTRACT This paper introduces the notion of channel splitting to augment the scaling of microchannels for a balanced microflu-idic cooling of 3DIC. The idea is to place appropriate number of channel splitters along various sections of microchannels to reduce the convective resistances at potential hotspots. The increases in pressure drops due to channel splitting are then redistributed by scaling the channel widths to match the coolant flowrates with the power distribution, which is usually nonuniform in practice. Unlike the existing techniques, this thermal balancing method requires no extra pump or valve. Only the customization of etching masks is needed for the deposition of silicon splitters and different sizes of microchannels. Experiment on a 4-layer multicore 3DIC stack shows that the proposed microchannel design technique can effectively reduce both the maximum temperature and thermal gradient in the 3D circuit.
2010 IEEE International 3D Systems Integration Conference (3DIC), 2010
This paper presents a cyber-physical (real-time sensepredict-adjust) thermal management for 3D mu... more This paper presents a cyber-physical (real-time sensepredict-adjust) thermal management for 3D multi-core system by micro-fluidic cooling. Auto Regressive (AR) model is used to predict future workload and the prediction is furnished by Kalman filtering to get rid of noises due to system variation. A thermal model is developed to sense thermal behaviour of the 3D system including micro-fluidic channels and estimate future thermal demand. The use of fine-grained, or non-uniform, flowrate control with channel clustering is then incorporated to adjust flow-rates based on the predicted future thermal demand in a real-time fashion. Experiment results show that under this cyber-physical scheme, the temperature of 3D multi-core cacheprocessor system is well maintained below threshold and a more even temperature distribution is achieved with lower fluid-pump power or total flow-rate overhead. For example, the total flowrate has a significant reduction of 72.1% under the fine-grained flow rate control 1 .
2013 18th Asia and South Pacific Design Automation Conference (ASP-DAC), 2013
This paper presents a fast and accurate steady state thermal simulator for heatsink and microflui... more This paper presents a fast and accurate steady state thermal simulator for heatsink and microfluid-cooled 3D-ICs. This model considers the thermal effect of TSVs at finegranularity by calculating the anisotropic equivalent thermal conductances of a solid grid cell if TSVs are inserted. Entrance effect of microchannels is also investigated for accurate modeling of microfluidic cooling. The proposed thermal simulator is verified against commercial multiphysics solver COMSOL and compared with Hotspot and 3D-ICE. Simulation results shows that for heatsink cooling, the proposed simulator is as accurate as Hotspot but runs much faster at moderate granularity. For microfluidic cooling, our proposed simulator is much more accurate than 3D-ICE in its estimation of steady state temperature and thermal distribution.
ASP Journal of Low Power Electronics (JOLPE), 2011
Existing three-dimensional (3D) integration of multi-core processor-cache system is confronted wi... more Existing three-dimensional (3D) integration of multi-core processor-cache system is confronted with the problem of die thermal run-away hazard. This teething problem is addressed by a real-time demand-based thermal management with non-uniform microfluidic cooling in this paper. A novel runtime temperature management is implemented to predict the real-time temperature demand based on software-sensing with prediction-and-correction. A 3D thermal model is developed to cater the real-time microfluidic thermal dynamics. An autoregressive (AR) prediction with correction is implemented by Kalman filtering to predict and correct the runtime power, which is further used to calculate the future temperature demand. With this software-sensing approach, thermal management can be performed in a cyber-physical fashion with real-time sensing, prediction-and-correction and fine-grained control. Compared to the existing works using on-chip temperature sensors, our closed-loop controller with software-sensing avoids the cost of sensor implementation and deployment. Our work analyzes and predicts the fine-grained temperature profile of multi-core processorcache system. It enables a number of microfluidic channels to be adjusted adaptively with different flow-rates to control the system temperature proactively as opposed to the static control with a uniform flow-rate for microfluidic channels. With the proposed cyber-physical temperature management scheme, it is shown that the temperature of multi-core system is suppressed below an acceptable thermal threshold. In fact, the fine-grained flow-rate control also achieves a more even temperature distribution and saves up to 72.1% of total flow-rate compared with uniform flow-rate controls.
Heat removal problem has been a bane of three dimensional integrated circuits (3DICs). Comparing ... more Heat removal problem has been a bane of three dimensional integrated circuits (3DICs). Comparing with other passive cooling techniques, microfluidic cooling appears to be an ideal cooling solution due to its high thermal conductivity and scalability. Without regarding to the fact of non-uniform power distribution of integrated circuits, existing microfluidic cooling with uniform cooling effort incurs large thermal gradient and wastes pump power. This can be avoided by the customized non-uniform cooling scheme proposed in this paper. The microfluidic channels are divided into clusters of relatively homogeneous power distribution and an appropriate flow rate setting is applied to each cluster based on the total flow rate and the maximum allowable temperature of the 3DIC. This paper proposes an efficient clustering algorithm to guide the division of microchannels into clusters and the allocation of cooling resources to each cluster in order to achieve an effective microfluidic cooling with minimal total flow rate. A compact steady state thermal simulator has been developed and verified. Supported by this fast and accurate thermal model, the proposed cooling method and clustering algorithm have been applied to a 3D multi-core testbench for simulation. Compared to the uniform flow rate cooling, the maximum temperature and thermal gradient were reduced under the same total flow rate settings. On the other hand, for a specific peak temperature constraint, up to 21.8% saving in total flow rate with moderate thermal gradients is achieved by the proposed clustered microfluidic cooling. been a problem for 2D large scale integrations as technology node scales and clock frequency increases , the stacking of circuits in 3DIC simultaneously increases power density and junction-to-ambient thermal resistances, making the circuits even more vulnerable to thermal induced hazards. Effective and efficient cooling techniques are thus needed to manage the thermal condition of 3D chips.
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