Agilent Technologies 4294A Specifications download pdf (Page 35)

2-7-3. Calibration

Most of the RF vector measurement instruments such as network analyzers need to be calibrated

each time a measurement is initiated or a frequency setting is changed. The RF I-V measurement

instrument requires calibration as well. At higher frequencies, a change in the instrument’s operat-

ing conditions, such as, environmental temperature, humidity, frequency setting, etc., have a greater

effect on measurement accuracy. This nature of RF vector measurement makes it difficult to suffi-

ciently maintain the calibrated measurement performance over a long period of time. Thus, users

have to periodically perform requisite calibration.

Note: Calibration is necessary each time a measurement setup is changed.

Calibration is executed in reference to three standard terminations, open, short and load, and all

three must be performed. To improve the accuracy of low dissipation factor measurements (high Q

factor), calibration with a low loss capacitor can be performed. The theory of calibration and appro-

priate calibration methods are discussed in Section 4.

2-7-4. Compensation

Two kinds of compensation functions are provided: open/short compensation for eliminating the

errors due to test fixture residuals and electrical length compensation for minimizing the test port

extension induced error. Practical compensation methods are discussed in Section 4.

2-7-5. Measurement range

RF I-V measurement method as well as network analysis covers the full measurement range from

low impedance to high impedance without ranging operation. All measurements are made at single

broad range.

2-7-6. DC bias

The internal DC bias source is connected to the center conductor of the coaxial test port and applies

a bias voltage to the DUT. The internal bias function can be set to either the voltage source mode or

the current source mode. The voltage source mode is adequate to the voltage-biased measurement

of capacitive DUT. The current source mode is to the current-biased measurement of inductive

DUT. Actual bias voltage and current across the DUT are monitored and, within specified

voltage/current output compliance ranges, automatically regulated at the same level as the bias set-

ting value regardless of the DUT’s DC resistance, thus allowing accurate DC bias to be applied

across the DUT. Since the internal bias source cannot output bias current large enough for inductor

measurements, generally, current-biased measurement (in excess of maximum output current)

requires an external bias method to be used. For biasing up to 5 A and 40 V in frequency range

below 1 GHz, the 16200B bias adapter compatible with RF I-V instruments is available.

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Agilent Technologies 4294A Specifications Page 35