HP an 346-2 free download

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H Balanced Circuit Measurement with an Impedance Analyzer/ LCR Meter/Network Analyzer Application Note 346-2 INTRODUCTION circuit is typically used in two conductors are at every point communications equipment equal in amplitude and opposite in How a Balanced Circuit Differs because a balanced circuit has the phase. Figure 2 shows an from an Unbalanced Circuit advantage of better spurious noise unbalanced cable which is an suppression. example of an unbalanced circuit. A balanced circuit has its Most measurement circuits in HP's electrical midpoint grounded. An Figure 1 shows a balanced cable impedance analyzers and LCR unbalanced circuit, however, has which is an example of a balanced meters are unbalanced. one side grounded. A balanced circuit. The voltages of the cable's +V +V -V 0V Figure 1. Balanced cable Figure 2. Unbalanced cable 1 Measuring a Balanced Circuit with an Unbalanced Measurement Instrument +V +V High A balanced circuit cannot be V terminal directly measured with an unbal- anced measurement instrument 0 -V Low A terminal because of the difference in their Balanced cable configuration. When measuring balanced circuits, Measurement Instrument the unbalanced measuring instru- ment requires a balun (balanced to Figure 3. Balanced cable measurement configuration unbalanced) transformer. A balun is a type of impedance-matching RF transformer. don't have to use the balun which To Calibrate/Compensate has the same impedance with the for (1): Figure 3 shows the configuration circuit under test. However, when for measuring a balanced circuit you measure the transmission or 1. Perform open/short/load with an unbalanced instrument. reflection of it, you have to use a calibration at the APC7