ADL5317 datasheet(13/16 Pages) AD

13 / 16 page

ADL5317

Rev. 0 | Page 13 of 16

DP 8200

DC POWER SUPPLY

HP89410A

VECTOR SIGNAL

ANALYZER

–

VPHV

VAPD

VPLV VSET

IPDM

ADL5317

–

μF

604

83nF

GE 273

–

+9V

FET BUFFER

ALKALINE

D CELLS

ALKALINE

D CELL

ALKALINE

D CELLS

+9V

20k

LNA

–12V

+12V

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

AGILENT

33250A

AD8067

Figure 27. Configuration for Pulse Response from IAPD to IPDM

ADL5317

EVALUATION BOARD

VAPD

FALT VPHV VPLV IPDM

VCLH

VSET

AGILENT

33250A

TDS5104

DC SUPPLIES/DMM

Figure 28. Configuration for Pulse Response from VSET to VAPD

NETWORK ANALYZER

OUTPUT

POWER

SPLITTER

AD8138

EVAL BOARD

––

ADL5317

EVAL BOARD

VAPD

VSET

COMM

VPHV

VPLV

60V

AD8045

IPDM

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 IAPD

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.

RC is chosen according to what current range is desired. Only

one cable is used between the Agilent 33250A and RC, 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 VAPD while

VSET is pulsed. Q1 and RC 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 IAPD to IPDM. 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 RF. This voltage is modulated to a

depth of 5% of full scale over frequency. The voltage across RF

sets the dc operating point of IAPD. RF values are chosen to result

in decade changes in IAPD. The output current at the IPDM pin

is fed into an AD8045 op amp configured to operate as a

transimpedance amplifier. The Feedback Resistor, RF, 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.

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