MICASDepartment of Electrical Engineering (ESAT)
Logic style
1. Standard CMOS logic2. Pseudo NMOS logic3. MCML (MOS Current Mode Logic--differential version of CSL)
4. CSL (CMOS Current Steering Logic)
AID–EMC: Low emission Digital Circuit Design
MICASDepartment of Electrical Engineering (ESAT)
Comparison---Maximum di/dt of an Inverter
1.00E+00
1.00E+01
1.00E+02
1.00E+03
1.00E+04
1.00E+05
1.00E+06
1.00E+07
1.00E+08
1 2 3 4logic style
di/d
t(am
p/s)
Standard CMOSPseudo NMOSCSLMCML
Why CSL ?
Target : Mixed-Mode Automotive Electronics Design
Key aspect : di/dt + Power + Area + Speed
Current Steering Logic
MICASDepartment of Electrical Engineering (ESAT)
CSL – Static CharacteristicStatic Characteristic
0
0.5
1
1.5
2
2.5
0 5 10 15 20 25
R
Vol
tage
(v)
VOH VOL VIL VIH
Design Parameter:
R=
Vdd=2.5vI=20uA
MICASDepartment of Electrical Engineering (ESAT)
CSL – Noise Margin
Noise Margin vs. R
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20 25
R
Noi
se M
argi
n(v)
NMHNML
Vdd=2.5vI=20uA
MICASDepartment of Electrical Engineering (ESAT)
CSL – Dynamic Characteristic
Propagation delay vs. R
0
1E-10
2E-10
3E-10
4E-10
5E-10
6E-10
0 5 10 15 20
R
tp(s
)tp
Vdd=2.5vI=20uA
MICASDepartment of Electrical Engineering (ESAT)
Vdd=3.3vI=10uAR=6
Cd
The Effect of Decoupling Capacitance
1p
10p,100p,1n,10n
There is a Trade off !
MICASDepartment of Electrical Engineering (ESAT)
Comparison of 16-bit RCA
Note: Vdd=1.5v The curve of CSL 16-bit RCA was obtained by calculating the real speed F of the circuit, given the different supply current I.
Solution:
power consumption management
• power down strategies, • sleeping transistors,• …
Power vs. Frequency (16-bit RCA)
0.00E+00
1.00E-04
2.00E-04
3.00E-04
4.00E-04
5.00E-04
6.00E-04
7.00E-04
8.00E-04
9.00E-04
0 50 100 150 200 250 300
Frequency(Mhz)
Pow
er(W
att)
CMOS
CSL
MICASDepartment of Electrical Engineering (ESAT)
Spectrum Analysis of di/dt
105
106
107
108
109
1010
70
80
90
100
110
120
130
140
150Power Spectral Analysis of the CMOS 16-bit RCA
Frequency (Hz)
Pow
er
105
106
107
108
109
1010
40
50
60
70
80
90
100
110
120Power Spectral Analysis of The Current Steering 16-bit RCA
Frequency (Hz)
Pow
er
GABARIT ?
30db decrease
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