Specifications

2-18
The reflection coefficient measurement never exhibits such high peak sensitivity for capacitive and
inductive DUTs because the directional bridge does not have the null balance point for reactive
impedance. The measurement sensitivity of the RF I-V method also varies, depending on the DUT’s
impedance, because the measurement circuit involves residuals and the voltmeter and current
meter are not ideal (Figure 2-16 (b).) (Voltmeter and current meter arrangement influences the mea-
surement sensitivity.) Though the measurable impedance range of the RF I-V method is limited by
those error sources, it can cover a wider range than in the network analysis method. The RF I-V
measurement instrument provides a typical impedance range from 0.2 Ω to 20 kΩ at the calibrated
test port, while the network analysis is typically from 2 Ω to 1.5 kΩ (depending upon the required
accuracy and measurement frequency.)
Figure 2-16. Measurement sensitivity of network analysis and RF I-V methods
Note: Typical impedance range implies measurable range within 10 percent accuracy.
Moreover, because the vector ratio measurement is multiplexed to avoid phase tracking error and,
because calibration referenced to a low loss capacitor can be used, accurate and stable measure-
ment of a low dissipation factor (high Q factor) is enabled. The Q factor accuracy of the network
analysis and the RF I-V methods are compared in Figure 2-17.