Datasheet

ADL5317
Rev. 0 | Page 13 of 16
DP 8200
DC POWER SUPPLY
HP89410A
VECTOR SIGNAL
ANALYZER
+
–
+
–
+
–
VPHV
VAPD
VPLV VSET
IPDM
ADL5317
+
–
+
–
+
–
+
–
+
–
33μF
604Ω
1kΩ
83nF
R1
GE 273
–
+
+9V
FET BUFFER
R
L
ALKALINE
D CELLS
ALKALINE
D CELL
ALKALINE
D CELLS
–
+
+9V
20kΩ
LNA
–12V
+12V
05456-041
Figure 26. Configuration for Noise Spectral Density and
Wideband Current Noise
TDS5104
ADL5317
EVALUATION BOARD
VAPD
FALT VPHV VPLV VSET VCLH
IPDM
DC SUPPLIES/DMM
1pF
R
C
R
C
AGILENT
33250A
Q1
AD8067
05456-027
Figure 27. Configuration for Pulse Response from I
APD
to I
PDM
05456-037
ADL5317
EVALUATION BOARD
VAPD
FALT VPHV VPLV IPDM VCLH
VSET
AGILENT
33250A
R
C
Q1
TDS5104
DC SUPPLIES/DMM
Figure 28. Configuration for Pulse Response from V
SET
to V
APD
NETWORK ANALYZER
OUTPUT R BA
POWER
SPLITTER
AD8138
EVAL BOARD
++
––
ADL5317
EVAL BOARD
VAPD
VSET
COMM
VPHV VPLV
60V 5V
AD8045
1V
50Ω
R
F
05456-040
IPDM
R
F
Figure 29. Configuration for Small Signal AC Response
The setup in Figure 26 is used to measure the output current
noise of the ADL5317. Batteries are used in numerous places to
minimize introduced noise and remove the uncertainty
resulting from the use of multiple dc supplies. In application,
properly bypassed dc supplies provide similar results. The load
resistor is chosen for each current to maximize signal-to-noise
ratio while maintaining measurement system bandwidth (when
combined with the low capacitance JFET buffer). The custom
LNA is used to overcome noise floor limitations in the
HP89410A signal analyzer.
Figure 27 shows the configuration used to measure the I
APD
pulse response. To create the test current pulse, Q1 is used in a
common base configuration with the Agilent 33250A, generating a
negative biased square wave with an amplitude that results in a
one decade current step on IPDM.
R
C
is chosen according to what current range is desired. Only
one cable is used between the Agilent 33250A and R
C,
while
everything else is connected with SMA connectors. A FET
scope probe connects the output of the
AD8067 to the
TDS5104 input.
The configuration in
Figure 28 is used to measure V
APD
while
V
SET
is pulsed. Q1 and R
C
are used to generate the operating
current on the VAPD pin. An Agilent 33250A pulse generator is
used on the VSET pin to create a 1.6 V to 2.4 V square wave.
The capacitance on the GARD pin is 2 nF for this test.
The setup in
Figure 29 is used to measure the frequency
response from I
APD
to I
PDM
. The AD8138 differential op amp
delivers a −1.250 V dc offset to bias the NPN transistor and to
have a 500 mV drop across R
F
. This voltage is modulated to a
depth of 5% of full scale over frequency. The voltage across R
F
sets the dc operating point of I
APD
. R
F
values are chosen to result
in decade changes in I
APD
. The output current at the IPDM pin
is fed into an
AD8045 op amp configured to operate as a
transimpedance amplifier. The Feedback Resistor, R
F
, is the
same value as that on the output of the
AD8138. Note that any
noise at the VSET input is amplified by the ADL5317 with a
gain of 30. This noise shows up on VAPD and causes errors
when measuring nanoamp current levels. This noise can be
filtered by use of the GARD pin. See the
GARD Interface
section for more details.