Datasheet
ADL5317
Rev. 0 | Page 12 of 16
1
2
V
SET
3
4
11
IPDM
12
NC
10
NC
9
GARD
5
VPHV
6
VCLH
7
GARD
8
VAPD
15
COMM
16
C
OMM
14
COMM
13
COMM
ADL5317
FALT
VSET
VPLV
VPHV
0.01μF
APD
1nF
1kΩ
I
APD
0.1μF
0.01μF
V
P_HIGH
0Ω
V
P_LOW
10kΩ
0Ω
0.01μF
0.1μF
TIA
DATA
PATH
1
2
3
4
11
SCAL
12
VOUT
10
BFIN
9
VLOG
5
VSUM
6
VNEG
7
VNEG
8
VPOS
15
COMM
16
COMM
14
COMM
13
COM
M
AD8305
VRDZ
VREF
IREF
INPT
I
PDM
10nA TO
1mA
AD8305 INPUT
COMPENSATION
NETWORK
4.7nF
2kΩ
OUTPUT
V
OUT
= 0.2 ×
LOG
10
(I
PDM
/1nA)
0.1μF
200kΩ
3V TO 12V
05456-025
1kΩ
1nF
2.5V
Figure 23. Interfacing the ADL5317 to the AD8305 for High Accuracy APD Power Monitoring
Measured rms noise voltage at the output of the AD8305 vs.
input current is shown in
Figure 24 for the AD8305 by itself
and in cascade with the ADL5317. The relatively low noise
produced by the ADL5317, combined with the additional noise
filtering inherent in the frequency response characteristics of
the
AD8305, result in minimal degradation to the noise
performance of the
AD8305.
5.5m
0
10n 1m
(A)
(V rms)
05456-034
5.0m
4.5m
4.0m
3.5m
3.0m
2.5m
2.0m
1.5m
1.0m
0.5m
100n 1μ 10μ 100μ
AD8305 ONLY
AD8305 AND
ADL5317
Figure 24. Measured RMS Noise of AD8305 vs. AD8305
Cascaded with ADL5317
CHARACTERIZATION METHODS
During characterization, the ADL5317 was treated as a high
voltage 5:1 precision current mirror. To make accurate
measurements throughout the entire current range, calibrated
Keithley 236 current sources were used to create and measure
the test currents. Measurements at low current and high voltage
are very susceptible to leakage to the ground plane.
To minimize leakage on the characterization board, the guard
pins are connected to traces that buffer VAPD and IPDM from
ground. The triax guard connector is also connected to the
GARD pin of the device to provide buffering along the cabling.
Figure 25 shows the primary characterization setup. The data
gathered is used directly, or with calculation, for all the static
measurements, including mirror error between IAPD and
IPDM
, supply tracking offset, incremental gain, and VAPD vs.
IAPD. Component selection is very similar to that of the
evaluation board, except that triax connectors are used in place
of the SMA connectors. To measure the pulse response, output
noise, and bandwidth measurements, more specialized test
setups are used.
ADL5317
CHARACTERIZATION BOARD
FALT VPHV VPLV VSET VCLH
VAPD
IPDM
DC SUPPLIES/DMM
TRIAX CONNECTORS:
SIGNAL - VAPD AND IPDM PINS
GUARD - GUARD PIN
SHIELD - GROUND
KEITHLEY 236
KEITHLEY 236
05456-026
Figure 25. Primary Characterization Setup