1
INA826 EMI RR Testing
2
Testing Methodology
• A sine wave applied to the input to simulate conducted EMI– 10MHz to 6GHz– -10dBm power level (100mVp)
• This conducted EMI signal will cause a change in the output offset of the part– DUT output is low-pass filtered– Change in offset is measured by a
6.5 digit DMM– Change in offset is input referred
Signal Generator
LPF
DMM
P
PEAKRF
V
OS
PEAKRFmV mV
V
A
V
VdBEMIRR
P 100log20log20)( __
100
3
Test Configurations
Differential Measurement– Signal applied to non-
inverting input– Inverting input grounded
Common-Mode Measurement– Signal applied to both
inputs
Bipolar (+/-12V) supplies were used with the reference pin grounded
4
Differential EMI RR of 3 Separate Units
The differential EMI RR performance is consistent across multiple INA826s
Differential EMI RR (Gain:1)
0
20
40
60
80
100
120
1.00E+07 1.00E+08 1.00E+09 1.00E+10
Frequency (Hz)
EM
I RR
(d
B)
INA826 #1
INA826 #2
INA826 #3
5
INA826 Differential EMI RR Gain Dependency
Differential EMI RR improves above 1GHz with increasing gain
Differential EMI RR (input referred) vs. Gain
0
20
40
60
80
100
120
1.00E+07 1.00E+08 1.00E+09 1.00E+10Frequency (Hz)
EM
I R
R (
dB
)
INA826 #2 Gain: 1
INA826 #2 Gain:10
INA826 #2 Gain:100
6
Common-Mode EMI RR of 3 Separate Units
Low frequency common-mode EMI RR performance has more unit-to-unit variation than differential EMI RR performance
Common-Mode EMI (1x Gain)
0
20
40
60
80
100
120
140
160
1.00E+07 1.00E+08 1.00E+09 1.00E+10
Frequency (Hz)
EM
I R
R (
dB
)
INA826 #2
INA826 #3
INA826 #4
7
INA826 Common-Mode EMI RR Gain Dependency
Increasing gain generally improves CM EMI RR at high frequencies
Common-Mode EMI RR Gain Dependance
0
20
40
60
80
100
120
140
160
1.00E+07 1.00E+08 1.00E+09 1.00E+10
Frequency (Hz)
EM
I RR
(d
B)
INA826 #2 Gain 1
INA826 #2 Gain 10
INA826 #2 Gain 100
8
Decoupling Capacitor Effects
Varying the decoupling capacitor size and type had negligible effect on EMI RR performance
Decoupling Capacitor Effects on Differential EMI RR
0
20
40
60
80
100
120
1.00E+07 1.00E+08 1.00E+09 1.00E+10Frequency (Hz)
EM
I RR
(d
B)
10uF X7R + 0.01uF C0G
10uF X7R + 0.1uF X7R
2x10uF X7R + 0.1uF X7R + 0.01uF C0G