Theory Of Operation - Keysight n1921a Operating And Service Manual

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Theory of Operation

Theory of Operation
The N1921/2A is integrated with the internal zeroing and calibration capability,
which eliminates the need for sensor calibration using an external reference source.
Keysight's patented technology integrates a DC reference source and switching
circuits into each N1921/2A, so you can zero and calibrate the N1921/2A while it
is connected to a device-under-test. This feature removes the need for connection
and disconnection from the calibration source, thereby reducing test times,
measurement uncertainty, and wear and tear on connectors. It is especially useful
in manufacturing and automated test environments where every second and every
connection counts. The N1921/2A can be embedded within test fixtures without
the need to switch in reference signals.
Figure 3-1
To ensure the accuracy of power measurements and improve measurement speed,
the N1921/2A uses a four- dimensional (4-D) modeling technique that measures
input power, frequency, temperature, and output voltage across the N1921/2A
specified measurement ranges. Data from this 4-D model is generated during
Keysight's initial factory calibration of the N1921/2A and stored in EEPROM.
All the compensation data is downloaded to the power meter/peak power
analyzer at power- on or when the N1921/2A is connected. Advanced algorithms
are used to quickly and accurately evaluate the N1921/2A against this model,
without requiring the power meter/peak power analyzer to interpolate the
calibration factors and linearity curves. If you run tests in which the frequency
changes often, such as testing multi-carrier amplifiers on different bands, you will
notice a marked improvement in measurement speed.
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Simplified Sensor Block Diagram
Keysight N1921A and N1922A Operating and Service Guide