Agilent Technologies 4294A Instrukcja Użytkownika Pobierz pdf (Strona 6)

6

Signal level dependency

The impedance characteristics of

some devices change drastically as

a function of the signal level. The

Agilent 4294A can sweep test

signal voltage, 5 mVrms to 1 Vrms

(1 mV resolution), or test signal

current 200 Arms to 20 mArms

(20 A resolution) to evaluate signal

level dependency.

Signal level dependency of a ceramic

capacitor with high permittivity

(signal-level swept from 5 mV to 1 V,

0.1 µF capacitor at 1 kHz)

DC level dependency

The DC component of an applied signal

often affects device impedance. The

4294A can sweep either the DC voltage

bias from –40 V to +40 V (with 1 mV

resolution) or the DC current bias

from –100 mA to +100 mA (with 40 A

resolution) to evaluate DC signal

dependency. This capability also

empowers analysis of the DC-voltage

bias dependency for C-V character-

ization of varactor diodes or other

DC-voltage bias dependent devices.

The DC level dependency figure

shows an example of varactor diode

measurement.

The DC bias auto level control (ALC)

function, based on a feedback loop

technique, accurately maintains the

applied DC voltage bias or current

bias. While the impedance of a device

might change during a sweep, this

ALC function insures that the signal

level setting is the actual signal level

applied to the DUT.

Varactor diode capacitance vs. DC voltage

characteristic. DC bias sweep from 0 V DC

to 5 V DC. f = 1 MHz

Efficient analysis with the

list sweep function

The list sweep function enables different

measurement setups in a single sweep

by dividing the sweep range into

segments. The measurement setup,

including the frequency range, aver-

aging time, measurement bandwidth,

test signal level (V or A), and DC bias

can be different for each segment.

The frequency range of each segment

can be continuous, separated, or

overlapped.

Evaluation of a crystal resonator

requires that the nominal resonant

frequency, the nominal anti-resonant

frequency, and some spurious frequen-

cies be determined. These parameters

can be efficiently measured by setting

an appropriate frequency range for

each segment.

Impedance Analysis Under Various Operating Conditions

Crystal resonator evaluation by list sweep

function

Edit screen of list sweep

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