Rohde & Schwarz ZPV - Measurement of Crystal Equivalent Circuit Parameters; General

2.5
Measurement of
Crystal
Equivalent
Circuit
Parameters
2.5.1
General
The Vector
Analyzer
ZFV in
conjunction
with a
frequency
counter,
an
FM-DC
signal
generator, a.
control
amplifier
and a
crystal
adapter
(
network
in
accordance
with
IEC
444 or
DIN
45
105
)
permits
measurement
of
crystal
equivalent
circuit
parameters.
For
this
purpose,
the
ZFV
must
be
fitted
with
the
Group-delay
Option
ZFV-B3.
The
ZFV supplies a
phase
-proportional
DC
voltage
which
after
amplification
in the
control
amplifier
pulls the
signal
generator
to the
series-resonance
frequency
of the
crystal.
The resonant
frequency
can
be read
off
on
the
frequency
counter.
If, in
addition, the
S-parameter
Option
ZFV-B2
is fitted,
it is
possible to
determine the
resonant
impedance
of
the
crystal
from
the
attenuation
at
resonance which is
read
out directly
on
the
lefthand
display.
Use of
a
desktop calculator
with
lEC-bus
Interface,
such as
Process
Con-
troller PPC,
in the
test
assembly permits
also
the
dynamic
inductance
and the
dynamic
capacitance
C^
to
be
determined.
To this
end, the ZPV
is
programmed for a
phase offset
Lf
i.e.
the
control
loop locks at
+•
>
From the two
frequencies
at
which
the phase
of
the
crystal
is
+
and the resonant
impedance, and
C^ are
calculated
by
means of
the desktop
calculator.
To select the
mode "measurement of
crystal
equivalent
circuit
parameters"
press the button
AUTO
.
Modes
T
and
AT must
be
switched off.
The
following
combinations can be
selected:
A
AUTO
LIN/REF
B
AUTO
LIN/REF
B/A AUTO
LIN/REF
Z
AUTO
Y
S21, S12
AUTO
Measurement of
voltage
in
channel. A
relative
to a
reference value
Measurement of
voltage in
channel
B
relative
to a
reference
value
Measurement of
voltage ratio
B/A
relative to
a
reference
value
Measurement
of
resonant
impedance
Measurement of
resonant
admittance
'
only
possibl.
with
Same as
with
B/A AUTO
LIN/REF
j
Option
ZPV-B2
Tiie phase measurement range is
limited to
about
+120°
in
these
modes
since
only
values
between
+90°
are required
for measuring
crystal,
equivalent
circuit parameters.
R
38535
-
27