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