HBM Genesis ISOBE5600, Руководство пользователя

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7.5 CMRR (Common Mode Rejection Ratio) Test
General information
Required equipment:
l
The LF generator
Acquisition settings:
l
1 kS/s sample rate
l
All channels are DC
-
coupled
l
Mode
-
, Filter
-
and Range settings as defined by the verification process.
HINT/TIP
The CMMR process uses a selected set of all Mode Filter and Range settings
supported by the
D evice U nder T est (DUT). The selection is done based on the
technical design of the DUT to ensure all design combinations are tested.
Procedure:
For isolated channels, the AC signal from the LF generator is between channel
input (signal and isolated ground) and system ground.
For non
-
isolated channels, only differential amplifiers can be CMRR
-
tested and
then the AC signal is applied between channel inputs (pos. and neg.) and
channel/system ground.
The input signal frequency is set to 80 Hz.
The input signal voltage (peak) is set to 3 * Range, unless the value is limited
by the amplifier specification or the LF generator. In this case the maximum
allowed/available voltage is used.
2000 Samples are acquired. The standard deviation of this data is then
calculated:
Vmeas .
The LF generator RMS output voltage is denoted as Vin .
The CMRR is calculated in dB as follows:
CMRR = 20log
10
( Vmeas / Vin )
ISOBE5600
100 I2716-4.0 en