What is the meaning of RF Calibration?
Which parameters we calibrate??
Of which component??
Please reply !!!
THANKS IN ADVANCE
When you are calibrating a device like this, you are applying a known power level. You measure the output voltage. With these know quantities, you can calculate the calibration coefficieents (slope and intercept in this case).
When you are operating the device, an unknown power level is applied. You figure out the value of this unknown input power level by combining the measured output voltage with the slope and intercept.
Calibration could be defined as transferring the accuracy of one (reference) system to another system. For example, if you send a spectrum analyzer or an RF power meter away for calibration, the technician will check that it is correctly measuring signal levels (against some trusted reference source) and if it is not they will adjust the machine to bring it back in spec.
When RF Power detector ICs are used in a larger system, they need to be calibrated. This is explained in detail in Application Note AN-1040.
Thanks for reply.
In AN-1040 I had seen following diagram.I had some doubts in it:
1) What is the meaning of Code high and Code low??
2)Unable to understand the last three steps.Please put some light over last three steps.
Thanks with Regards
This is a two point calibration. For example, when you set the power level to the top end of the range, the ADC gives you a output value; this is CODEhigh. Same thing for low power and CODElow. Then you use these values along with the known power levels that you applied to calculate the SLOPE and INTERCEPT which you then need to store in non volatile RAM or in the boot code/firmware of your system.
Here slope is like some proportion and intercept is also like that.But here i am not able to understand about reference value?
Are we calculating Intercept to get reference value?
In doing calibration, we first assume that we are modeling the behavior of the device using the equation.
Vout = Slope x (Pin - Intercept) or Pin = Vout/Slope + Intercept
Every device has different values for Slope and Intercept. So the goal of the calibration process is to figure out these values for each device. The whole idea of calibration is that after calibration, you can apply an unknown RF power level to the device and using the equation Pin = Vout/Slope + Intercept, you can figure out the value of this unknown power leve.
Here Vout is output voltage corresponding to the input (unknown RF power level) applied????
THANKS FOR REPLY,
I COMPLETELY UNDERSATND THE CONCEPT.
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