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MICAS Department of Electrical Engineering (ESAT) Update of the “Digital EMC project” March 1st, 2006 AID–EMC: Low Emission Digital Circuit Design Junfeng Zhou Wim Dehaene KULeuven ESAT-MICAS
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MICAS Department of Electrical Engineering (ESAT) Outline 1.Test chip finished 2. Theoretical analysis 3. Chip Testing proposal
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MICAS Department of Electrical Engineering (ESAT) Test layout for EMI regulator done Layout transferred end of january, to be integrated in complete test chip. Taped out is/was when? One last change …
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MICAS Department of Electrical Engineering (ESAT) Last change of the layout add extra output pin Vcontrol 1.Using metal 5 (can be cut in case of trouble) 2.Making measurements more flexible 3.Shaping the TF according to the values of Caux and Raux
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MICAS Department of Electrical Engineering (ESAT) Outline 1.Test chip finished 2. Theoretical analysis 3. Chip Testing proposal
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MICAS Department of Electrical Engineering (ESAT) Simplified model 4 nodes, difficult to analyze p1 p3 p2 z1
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MICAS Department of Electrical Engineering (ESAT) Simplified model p1 p3 p2 Vi Ii Iout Short to ground
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MICAS Department of Electrical Engineering (ESAT) Stability analysis - Small signal analysis Approximation: p1 p2 p3 z1 dominant pole second pole High frequency pole High frequency, left half-plane zero >3 for > 72° phase margin Gain of the current source Stability ~ Caux/Ctank
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MICAS Department of Electrical Engineering (ESAT) Stability analysis – Simulation vs. Calculation Spectre simulation Maple calculation Raux=1.852K, Caux=20p,Ctank=100p Stability vs. Iload φ> 72 ° Iload =192.7u A
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MICAS Department of Electrical Engineering (ESAT) Current TF analysis H(s)=Idd(s)/Iin(s) dominant pole second pole third pole High frequency zero left half-plane zero
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MICAS Department of Electrical Engineering (ESAT) Current TF- simulation vs. calculation Spectre simulation Maple calculation Iload =80u A, Raux=1.852K, Ctank=100p Infinite Attenuation ?? Not in reality!
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MICAS Department of Electrical Engineering (ESAT) Model revisited p1 p3 p2 z1 Cdb1
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MICAS Department of Electrical Engineering (ESAT) Current TF- simulation vs. calculation Spectre simulation Maple calculation Iload =80u A, Raux=1.852K, Ctank=100p TF vs. Caux
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MICAS Department of Electrical Engineering (ESAT) Maximum Attenuation Maple calculation Iload =80u A, Raux=1.852K, Ctank=100p TF vs. Caux Cut off freq. ~ 1/Caux Large attenuation requires Large Ctank and/or small Cdb1 Cascode structure !
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MICAS Department of Electrical Engineering (ESAT) Caux/Ctank and time domain ∆Vdd ∆Vdd Caux = 1..5 pF Equations to be calculated However: ∆Vdd ~ Caux/Ctank in damped case
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MICAS Department of Electrical Engineering (ESAT) Conclusion Regulator design criteria for Caux,Ctank Stability ~ Caux/Ctank Current transfer function (i.e. di/dt attenuation) Cut off freq: Gm/Caux Max. attenuation: Cdb1/(Cdb1+Ctank) Time domain ∆Vdd Caux/Ctank Conclusion Caux/Ctank determines stability and ∆Vdd. More stable also means a larger ∆Vdd ! Design for small Cdb1 Similar story possible for Gm, Gm1
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MICAS Department of Electrical Engineering (ESAT) Chip Testing proposal Test: 1.List of tests for di/dt 2.Test setup proposal To be designed => test board 3. Will we also do the emission tests ?
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MICAS Department of Electrical Engineering (ESAT) List of tests for di/dt For the special EMC regulator: 1.Current pulse measurement, 2. The current TF as a function of Ctank, Caux 3. Measurement of di/dt reduction vs. Ctank, Caux and decoupling cap, 4. Influence of different loads provided by AMIS -- D-FF or MS-FF -- number of gates -- distributed clocks over time ……
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MICAS Department of Electrical Engineering (ESAT) Test setup for di/dt measurement 1. For di/dt transient measurement 1. OPAMP, BW ? 2. Current probe ? 3. Transformer ? DUT is EMI regulator EMI regulator + V-regulator
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MICAS Department of Electrical Engineering (ESAT) Test setup for Transfer function 2. For Transfer Function measurement
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MICAS Department of Electrical Engineering (ESAT) Design of Test Board To be designed … 1. OPAMP, BW ? 2. Current probe ? 3. Transformer ?
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MICAS Department of Electrical Engineering (ESAT) Measurement of Emission IEC 61967-4 International Standard Spectrum Analyzer 1 Ohm IC Chip under test Outer side Inner side IEC 61967-2 International Standard radiated mode conducted mode 1/150 ohm method can be foreseen on testboard Do we need to measure this? How ?
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MICAS Department of Electrical Engineering (ESAT) Future work 1. Test board ?, Chip measurement, Finish the theoretical analysis, 2. Continue research on the Clock strategy: SSCG
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MICAS Department of Electrical Engineering (ESAT) Questions Thank you for your attention
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