... | @@ -2,15 +2,13 @@ |
... | @@ -2,15 +2,13 @@ |
|
|
|
|
|
= Stage 3 Variable Amplification
|
|
= Stage 3 Variable Amplification
|
|
|
|
|
|
To be able to measure signals within a wide input voltage range, a variable amplification stage is mandatory. This stage will, depending on the signal amplitude, amplify or attenuate the signal.
|
|
To be able to measure signals within a wide input voltage range, a variable amplification stage is mandatory.
|
|
This ensures that the ADC, at the end of the front-end, always samples at nearly full scale.
|
|
This stage will, depending on the signal amplitude, amplify or attenuate the signal. This ensures that the ADC, at the end of the front-end, always samples at nearly full scale.
|
|
Because of the characteristics of the chosen ADCs of the OpenLab front-end, the acceptable input range is defined as 0V to 3.3V.
|
|
Because of the characteristics of the chosen ADCs of the OpenLab front-end, the acceptable input range is defined as 0V to 3.3V.
|
|
This includes the external ADCs, needed by the FPGA-based solution, as well as the integrated ADCs of the microcontroller-based solution.
|
|
This includes the external ADCs, needed by the FPGAbased solution, as well as the integrated ADCs of the microcontroller-based solution.
|
|
As a side effect of the ADC input protection stage, the input range of the ADC is limited from 0.8V to 2.7V.
|
|
As a side effect of the ADC input protection stage, the input range of the ADC is limited from 0.8V to 2.7V. The reason for this limitation is the characteristics of standard silicon-based diodes.
|
|
The reason for this limitation is the characteristics of standard silicon-based diodes. Diodes will not start to clip voltages at a strict defined level.
|
|
Diodes will not start to clip voltages at a strict defined level. The signal that is passed through the protection stage will get distorted in connection with the characteristic curve of the used diode.
|
|
The signal that is passed through the protection stage will get distorted in connection with the characteristic curve of the used diode.
|
|
|
|
In case of the OpenLab front-end, signals with a voltage range outside of 0.8V – 2.7V will get distorted.
|
|
In case of the OpenLab front-end, signals with a voltage range outside of 0.8V – 2.7V will get distorted.
|
|
So the voltage of the measured signal has to be prepared by the variable amplification stage to fulfill the previously mentioned limitations.
|
|
|
|
|
|
|
|
{empty} +
|
|
{empty} +
|
|
|
|
|
... | | ... | |