STMicroelectronics Demonstration board based on the TSC102 STEVAL-ISQ010V1 STEVAL-ISQ010V1 Data Sheet

12/23

DocID16754 Rev 3

The common-mode rejection ratio (CMR) measures the ability of the current sensing 
amplifier to reject any DC voltage applied on both inputs V

p

 and V

m

. The CMR is referred 

back to the input so that its effect can be compared with the applied differential signal. The 
CMR is defined by the formula:

The supply voltage rejection ratio (SVR) measures the ability of the current sensing 
amplifier to reject any variation of the supply voltage V

CC

. The SVR is referred back to the 

input so that its effect can be compared with the applied differential signal. The SVR is 
defined by the formula:

The input offset voltage is defined as the intersection between the linear regression of the 
V

a1

 versus V

sense

 curve with the X-axis (see 

a11

 is the output voltage with 

V

sense 

= V

sense1 

= 50 mV and V

a12

 is the output voltage with V

sense 

= V

sense2 

= 5 mV, then 

V

os

 can be calculated with the formula:

The amplification gain Av is defined as the ratio between the output voltage and the input 
differential voltage.

CMR

20

–

ΔV

a1

ΔV

icm

Av

⋅

------------------------------

log

⋅

=

SVR

20

–

ΔV

a1

ΔV

cc

Av

⋅

---------------------------

log

⋅

=

V

os

V

sense1

V

sense1

V

sense2

–

V

a11

V

a12

–

------------------------------------------------

V

out1

⋅

⎝

⎠

⎛

⎞

–

=

Av

V

out

V

sense

------------------

=