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A Low-Power True Random Number Generatorusing Random Telegraph Noise of Single

Oxide-Traps

Class presentation of advanced VLSI design

University of tehran, FALL 2006

Represented by Mehdi Mohamadi

Adopted from ISSCC 2006

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What’s Random Number ?

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Produce and sample noise signal

• Pseudo Randomn Number Generator (PRNG)

Random Number=f( seed)

• True Random Number Generator (TRNG)

Random Number = f( noise)

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Pseudo Random

• Middle square method

seed= 345674

seed ² = 119490514276

New seed = 490514

problem : if seed=0 => generator freeze

Use by ENIAC ( 1946-1995)

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module von_neumann(clk,reset,out);output [9:0] out;input clk,reset;reg [19:0] a;reg [9:0] out;always @(posedge clk)begin if (reset) out=10'b1001011010; else begin a=out*out; out=a[14:5]; end endendmodule

Synthesis on Stratix

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Pseudo Random

• 6 bit pseudo random number generator

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• Pseudo Random : complex hardware ,Low frequency ,unreliable data

=> week security

Why pseudo ???When we can flip a coin!!

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True Random

• Chaos theory • Thermal Noise

But Noise?

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• Noise Effect

Does Differential comparator help us ?

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Intel RNG

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What’s new in this design?

• Low power and Area consumption • Noise tolerant• Voltage variation tolerant

( suitable for security controller)

=> introduce new field oxide trap

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• Large noise amplitudes (~1mV) for small area devices

• White noise in certain frequency bands

• … but strong fluctuations in the low-frequency noise

Noise of small area MOSFETs

1chip - 6 different devicesW/L = 0.16µm/0.12µm

Vds=1V, Vgs,eff=0.25V

10 -3

10 -4

10 -5

10 -6

10 -7

10 -8

10 510 410 310 210 110 0

Gat

e re

ferr

ed v

olt

age

no

ise

[VH

z-0.5]

Frequency [Hz]

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• But is probability of ‘1’ =probability of ‘0’ ??

=> Von Neumann algorithm

CLK

+

-

Vref.

Randomnumbers

Decoder

+

-

QualityCheck

HPF

von Neumann Algorithm:

00 no data

01 ‘1’

10 ‘0’

11 no data

10 1 1 0 1

V

random numbers

Vref.

t

CLK

Vnoise

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TRNG Schematics:Noise Source and Amplifier

noise1 noise2

Vbias1

R12R11

C11

0.16/0.24 0.16/0.24

C12

T3

Ti2Ti1

T2T1

Si Si

Vref_amp Vref_amp

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TRNG Schematics:Noise Source and Amplifier

10 times10 timesrepeatedrepeated

• Auto calibration procedure determines best fitted noise source

noise1 noise2

Vbias1

R12R11

C11

0.16/0.24 0.16/0.24

C12

T3

Ti2Ti1

T2T1

Si Si

Vref_amp Vref_amp

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TRNG Schematics:Filter

• Low accuracy of these devices is no problem here (filter corner frequency has no fixed value, but needs to be ~ 5-20kHz)

C31 C32

noise1 noise2

Vref_comp

R32R31

f_noise1 f_noise2 Vbias2 Vbias3

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TRNG Schematics:Comparator

• Comparator is optimized for low mismatch and low hysteresis

T7T6

CLK CLK

f_noise1 f_noise2

T9T8

T11T10

T13T12

T5T4

out1 out2

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TRNG – Measured Output Data

• Raw data rates of up to 5MHz possible• However correlation reduces randomness

-> necessity to apply post processing (v. Neumann algorithm)

Sampling frequency = 500kHz

Time [µs]-50 -40 -30 -20 -10 0 10 20 30 40 50

ou

t 1 -

ou

t 2 [

V]

-2

-1

0

1

2

Sampling frequency = 5MHz

Time [µs]-10 -5 0 5 10

ou

t 1 -

ou

t 2 [

V]

-2

-1

0

1

2

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TRNGBasic Electrical Performance

Area (in 0.12µm CMOS): 0.009 mm² (analog part only)Power consumption: < 20µW + 30µW/MHz *fclock

PSRR @500kHz (simulated): ~ 30dBCMRR @500kHz (simulated): ~ 30dBRaw data rate (typical / max.): 500kHz / 5MHz

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Random Number Data rate

Sampling Frequency [Hz]2x105 4x105 6x105 8x105 106

Bit

eff

icie

nc

y(4

dif

fere

nt

no

ise

so

urc

es

)

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

4 different noise sources on the same die

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Sampling Frequency [Hz]2x105 4x105 6x105 8x105 106

Me

an

Va

lue

(4 d

iffe

ren

t n

ois

e s

ou

rce

s)

0.2

0.3

0.4

0.5

0.6

0.7Mean value Mean value after v.Neumann correction

Random Numbers - Mean Value

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Random Numbers - Mean Value

Sampling Frequency [Hz]2x105 4x105 6x105 8x105 106

Me

an

Va

lue

(4 d

iffe

ren

t n

ois

e s

ou

rce

s)

0.2

0.3

0.4

0.5

0.6

0.7Mean value Mean value after v.Neumann correction

4 different noise sources on the same die

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REFERENCES• [1] Ralf Brederlow1, Ramesh Prakash 2, Christian Paulus3,Roland Thewes1

“A Low-Power True Random Number Generator using Random Telegraph Noise of Single Oxide-Traps “ ISSCC 2006

• [2] B. Jun, P. Kocher, “The Intel Random Number Generator,” white paper,

http://www.cryptography.com/resources/whitepapers/IntelRNG.pdf, 1999.• [3] Craig S Petrie and J Alvin Connelly, “ A Noise-Based IC Random Number

Generator for Applications in Cryptography” IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—I: FUNDAMENTAL THEORY AND APPLICATIONS, VOL. 47, NO. 5, MAY 2000

• [4] Barry paton, Dalhousie University,” Fundamentals of Digital Electronics”

March 1998 Edition