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Exploring 3D Power Distribution Network Physics Xiang Hu 1, Peng Du 2, and Chung-Kuan Cheng 2 1 ECE Dept., 2 CSE Dept., University of California, San Diego.

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Presentation on theme: "Exploring 3D Power Distribution Network Physics Xiang Hu 1, Peng Du 2, and Chung-Kuan Cheng 2 1 ECE Dept., 2 CSE Dept., University of California, San Diego."— Presentation transcript:

1 Exploring 3D Power Distribution Network Physics Xiang Hu 1, Peng Du 2, and Chung-Kuan Cheng 2 1 ECE Dept., 2 CSE Dept., University of California, San Diego 10/25/2011

2 Page  2 Outline  Introduction  3D power distribution network (PDN) model –Circuit model –Current model  3D PDN analysis flow  Experimental results –On-chip Current Distribution –Resonance phenomena  Noise reduction techniques –Larger decap around TSVs –Reduce Tier to tier impedance  Conclusions

3 Page  3 Introduction  Power delivery issues in 3D ICs –More tiers => More current –Same footprint on package –TSVs and µbumps between tiers  Coarse power grid models –Missed detailed metal layer information –Current source models  Detailed 3D PDN analysis –Frequency domain: resonance behavior –Time domain: worst-case noise

4 Page  4 3D PDN Circuit and Current Models  Circuit Model –Lump model: Two-port model for chip between tiers –Fine grid model: all metal layers: m1+  Current Model –Power law –Phase in f domain

5 Page  5 3D PDN Distributed Model[1]  Power grid –Structure: M1, M3, M6, RDL –Each layer extracted in Q3D  T2T: TSV+μbump –Modeled as an RLC element  Package: C4 bump based RLC model [1] X. Hu et al., “Exploring the Rogue Wave Phenomenon in 3D Power Distribution Networks,” IEEE 19th Conf. on Electrical Performance of Electronic Packaging and Systems, Oct. 2010, pp. 57–60.

6 Page  6 Frequency-Domain Current Stimulus Model  Noise depends on the current model  Rents rule power law: –P : power consumption –A : area –k : constant number –γ : exponent of the power law  Current configurations –γ =0 : single current load –0< γ <1 : taper-shaped current distribution –γ =1 : uniform current distribution –In f domain, we can tune the phase

7 Page  7 3D PDN Analysis Flow

8 Page  8 Experiment Base Setup –Two-tier PDN –TSV setup: 3x4 TSVs connected to M1 and AP on both side –5nF/mm 2 decap on T1; 50nF/mm 2 decap on T2 –2x2 C4 on T1 AP Per bump inductance: 210pH Per bump resistance: 18.7mΩ M1M3M6APTSV T1T2 Pitch (um) Width (um) Pitch (um) Width (um) Pitch (um) Width (um) Pitch (um) Width (um) Pitch (um) Width (um) X step Y step

9 Page  9 Current Model: Input on T1  Two-tier PDN + VRM, board, and package –Decap: 5nF/mm 50nF/mm –Current: T1; distr.( γ=0, 0.5, 1 )  Probe –A: T1 TSVs –B: T1 between TSVs –C: T2  Observation –Smaller γ => larger noise –Resonance at non-TSVs, but not at TSVs VRM-brd brd-pkg T1-T2

10 Page  10 Current Model: Noise Map w/ Input on T1 T1 T2 γ=0γ=0 γ= 0.05 γ=1

11 Page  11 Current Model: Input on T2  Two-tier PDN + VRM, board, and package –Decap: 5nF/mm 50nF/mm –Current: T2; distr.( γ=0, 0.5, 1 )  Probe –A: T1 TSV location –B: T1 non-TSV location –C: T2  Observation –Smaller γ => larger noise

12 Page  12 Current Model: Noise Map w/ (1GHz) T1 T2 γ=0γ=0 γ= 0.05 γ=1

13 Page  13 Resonance Phenomena  Decap: 5nF/mm 50nF/mm  Current: T1 or T2, unif. (γ=1)  Observation: resonance vary with decap configurations Global mid-freq resonance non-TSV locations. From lumped model: No resonance TSV locations No mid-freq resonance peak due to “R m1 ” Probe: T1 Current: T1 Probe: T2 Current: T2

14 Page  14 Decap: Larger Decap Around TSVs  Decap: 50nF/mm 5nF/mm –Case 1: uniform –Case 2: half of decap at  Observation: Case 2 is better Probe: T1 between TSVs Current: T1 unif. Probe: T2 Current: T2, unif Probe: T2 Current: T1 unif

15 Page  15 Tier to Tier Impedance: Number of TSVs SetupCase 1Case 2Case 3 TSV X step (M1 segments) TSV Y step (M3 segments) # TSV41232 TSV Setup

16 Page  16 Tier to Tier Impedance: Number of TSVs  TSV(Xpitch,Ypitch) –Case 1: (40, 100) –Case 2: (20, 40) –Case 3: (15, 18)  Current: T1, unif. ( γ=1 )  Probes –A: T1 TSV –B: T1 between TSVs –C: T2  Observation –noise drops as #TSV increases –resonance f drops as #TSV increases As T2T impedance becomes smaller, resonance frequency is determined by both C d1 and C d2 Resonant f determined by C d1

17 Page  17 Conclusion  On-chip power network model  Current distribution model –Power law current distribution model reflects the current-area relation  Decap: Various on-chip resonances  Techniques of reducing 3D PDN noise –Larger decap around TSV area –Small tier to tier impedance

18 Page  18 Thank You! Q & A


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