adl5304 Analog Devices, Inc., adl5304 Datasheet

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adl5304

Manufacturer Part Number
adl5304
Description
High Speed, 200 Db Range, Logarithmic Converter
Manufacturer
Analog Devices, Inc.
Datasheet

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Data Sheet
FEATURES
Optimized for very fast response at all input currents
10 decades of input range: 1 pA to 10 mA
Law conformance: ±0.25 dB from 100 pA to 100 μA
Log ratio or fixed-intercept operation
Precision voltage references and reference current
Adaptive photodiode (PD) bias for low dark current
Programmable log slope and intercept
Default log slope of 10 mV/dB at VLOG pin
Single- or dual-supply operation
APPLICATIONS
High accuracy optical power measurement
Wide range baseband log compression
Versatile detector for high speed APC loops
GENERAL DESCRIPTION
The
response and low noise over a 200 dB (1 pA to 10 mA) measure-
ment range. The
10 mV/dB (200 mV/decade); other values are easily configured.
Logarithmic intercept can be programmed over a wide range
with the internal 100 nA current source or externally for log ratio
applications. The default intercept value of 3.162 fA places the
midpoint of the measurement range of 100 nA at V
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
Overall bandwidth of >4 MHz for inputs >1 μA
Bandwidth: 25 kHz at input of 1 nA and 350 kHz at 10 nA
ADL5304
is a high speed logarithmic converter with fast
ADL5304
provides a nominal logarithmic slope of
R
MNTR
IDEN
IREF
VSM1
VSM2
VSM3
VSM4
INUM
2
3
4
5
6
7
8
IMON
1.5V
1.5V
MONITOR AND
30
SIMPLIFIED BLOCK DIAGRAM
(1.1× I
LOG
PD BIAS
= 1.5 V.
NUM
VNUM
VDEN
)
32
9
INNM
INDN
Figure 1.
10
31
COMM NMFS VNEG DNFS
V
V
1P5V
100nA
NUM
DEN
11
COMPENSATION
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
TEMPERATURE
A single positive supply of 5 V is all that is required for operation
over a specified 1 pA to 3 mA input range. Dual-supply operation
extends the specified input current range to 10 mA.
The
argument. The numerator input, I
NPN transistor, connected in a feedback path around a low offset
JFET amplifier. The denominator current, I
same way, which allows for log ratio operation. The input summing
nodes (INUM and IDEN) operate at a constant default voltage of
1.5 V. The VSM1 to VSM4 pins flank the INUM and IDEN inputs
to provide a guard voltage to minimize leakage currents.
Adaptive photodiode biasing is provided for optical measurements.
A monitor current 1.1 times I
an external resistor, R
resistance (R
1st order keeps the internal PD junction at 0 V to minimize
dark current.
The VLOG output is buffered and can be rescaled through
internal gain setting resistors. The internal I
−400 μA to +400 μA as I
to 10 mA. This corresponds to 0.5 V to 2.5 V at the VLOG pin
in the default configuration shown in Figure 1.
Accurate 1.5 V (Pin 1P5V) and 2.0 V (Pin 2VLT) reference outputs
allow precise repositioning of the intercept using external resistors.
The
and specified for operation from −40°C to +85°C.
1.5V
ADL5304
26
BSDC
12
ADL5304
ADL5304
BIAS AND
28
1kΩ
High Speed, 200 dB Range,
V
REF
V
2VLT
NEG
13
2V
17
I
LOG
S
) applies a voltage across the photodiode that
VPOS
14
accepts two current inputs to the logarithmic
is available in a 32-lead, 5 mm × 5 mm LFCSP
29
Logarithmic Converter
1kΩ
7.5kΩ
5kΩ
ACOM
15
27
MNTR
DCBI
©2011 Analog Devices, Inc. All rights reserved.
5kΩ
HFCP
NUM
16
, at 10 times the photodiode series
24
23
22
21
20
19
18
NUM
changes over 10 decades from 1 pA
INPS
INMS
VLOG
SCL1
SCL2
SCL3
ACOM
is output at the IMON pin, and
NUM
, flows in the collector of an
DEN
LOG
ADL5304
, is treated in the
varies from
www.analog.com

Related parts for adl5304

adl5304 Summary of contents

Page 1

... SIMPLIFIED BLOCK DIAGRAM BSDC 2VLT IMON VNUM INNM 1P5V 1.5V MONITOR AND PD BIAS BIAS AND 100nA (1.1× NUM REF 1.5V 3 ADL5304 4 V NUM TEMPERATURE 5 COMPENSATION 6 V DEN 7 1.5V COMM NMFS VNEG DNFS VDEN INDN 1kΩ V NEG Figure 1. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. ...

Page 2

... Theory of Operation ...................................................................... 17   Basic Concepts............................................................................ 17   Optical Measurements............................................................... 17   Circuit Description .................................................................... 18   Applications Information .............................................................. 25   Using the ADL5304.................................................................... 25   Using a Negative Supply ............................................................ 26   Evaluation Board Schematic and Silkscreens ............................. 27   Outline Dimensions ....................................................................... 29   Ordering Guide .......................................................................... 29 Rev Page Data Sheet   ...

Page 3

... S 0 3.0 ADL5304 Unit A A mV/°C mV mV/dec mV/dec fA mV μV/° μA MΩ V μV/√Hz kHz kHz MHz MHz μs μs μs μs V Ω V μV/° μV/°C ...

Page 4

... ADL5304 Parameter POWER SUPPLY VPOS Quiescent Current VNEG 6 Quiescent Current 1 Slope is of the same magnitude but opposite sign for input applied to IDEN OFS / /10 . Note that the error dependent on three parameters REF Z 3 Output noise and small signal bandwidth are functions of input current; measured from the INUM input to the VLOG output. See the Characteristics section ...

Page 5

... V section of this specification is not implied. Exposure to absolute 20 mA maximum rating conditions for extended periods may affect device reliability. 61.6°C/W 1.2°C/W ESD CAUTION 0.6 W 125°C −40°C to +85°C −65°C to +150°C 300°C Rev Page ADL5304 ...

Page 6

... EPAD PAD Exposed paddle. Connect the exposed paddle to the VSM1 to VSM4 pins to provide low leakage guard INPS PIN 1 VSM1 2 23 INMS INDICATOR VSM2 3 22 VLOG ADL5304 INUM 4 21 SCL1 IDEN 5 20 SCL2 TOP VIEW IREF 6 19 SCL3 (Not to Scale) VSM3 7 ...

Page 7

... I CURRENT (A) NUM for Multiple Values of I NUM (Decade Steps from 100 mA) ADL5304 +85°C +70°C +25°C 0°C –40°C 1m 10m +85°C +70°C +25°C 0°C –40°C 1m 10m 1mA 100µA 10µ ...

Page 8

... ADL5304 3.5 3.0 2.5 2.0 1.5 1.0 0 10p 100p 1n 10n 100n 1μ I CURRENT (A) DEN Figure 9. V vs. I for Multiple Values of I LOG DEN (Decade Steps from 100 mA) 3.0 2.5 2.0 1.5 1.0 0.5 0 –0.5 –1.0 –1.5 –2.0 –2.5 –3.0 1p 10p 100p 1n 10n 100n 1μ I (A) NUM Figure 10. Law Conformance Error Distribution vs σ ...

Page 9

... TEMPERATURE (°C) Figure 19. 2VLT Drift vs. Temperature 2.000 1.995 1.990 1.985 1.980 1.975 1.970 –20 –15 –10 LOAD CURRENT (mA) Figure 20. 2VLT vs. I (Positive Current Defined into 2VLT Pin) LOAD ADL5304 1.20 +3σ –3σ –5 0 ...

Page 10

... ADL5304 10 0 –10 –20 –30 1mA –40 100µA 10µA 1µA –50 100nA 10nA –60 1nA –70 100 1k 10k 100k FREQUENCY (Hz) Figure 21. Small Signal AC Response from I Decade Steps from mA, I 100 10 1 0.1 STEP IS ANALYZER ARTIFACT 0.01 100 1k 10k 100k FREQUENCY (Hz) Figure 22 ...

Page 11

... Either Side of Mean) 250 200 150 100 50 0 –1.0 –0.5 0 0.5 INUM V (mV) OS Figure 31. (V − Histogram at 25°C NUM SUM 250 200 150 100 50 0 1.496 1.498 1.500 1.502 1P5V VOLTAGE (V) Figure 32. 1P5V Histogram ADL5304 +3σ –3σ 1.0 1.504 ...

Page 12

... ADL5304 300 250 200 150 100 50 0 1.996 1.998 2.000 2VLT VOLTAGE (V) Figure 33. 2VLT Histogram 300 250 200 150 100 50 0 195.0 197.5 200.0 INUM SLOPE (mV/dec) Figure 34. Distribution of Logarithmic Slope (Nominally 200 mV/dec) 140 120 100 95.0 97.5 100.0 I CURRENT (nA) REF Figure 35 ...

Page 13

... SCL3 ACOM 18 ACOM HFCP 1kΩ 0.1µF V NEG HP3577B 2VLT VPOS DCBI INPS 24 2V BIAS AND INMS 23 V REF VLOG 22 SCL1 I 21 LOG 5kΩ 5kΩ SCL2 20 7.5kΩ 19 SCL3 ACOM 18 ACOM HFCP 1kΩ 1kΩ 0.1µF V NEG ADL5304 ...

Page 14

... LECROY SDA6000 SCOPE INPUT INPUT AP1M 1MΩ BSDC 2VLT VPOS 1P5V DCBI INPS 24 1.5V 2V INMS BIAS AND 100nA 23 V REF VLOG 22 ADL5304 SCL1 I 21 NUM LOG 5kΩ 5kΩ SCL2 TEMPERATURE 20 COMPENSATION 7.5kΩ SCL3 19 DEN ACOM 18 ACOM HFCP 1kΩ ...

Page 15

... LECROY SDA6000 SCOPE INPUT TRIGGER INPUT 50Ω AP1M 1MΩ 1kΩ TO 100kΩ LOAD 2VLT VPOS DCBI INPS 24 2V INMS 23 V REF VLOG 22 SCL1 I 21 LOG 5kΩ 5kΩ SCL2 20 7.5kΩ 19 SCL3 ACOM 18 ACOM HFCP 1kΩ 1kΩ 0.1µF V NEG ADL5304 ...

Page 16

... I NUM scale, and the output voltage ( plotted on a linear scale. LOG The other input current is fixed. Typically, slope is denoted as V with units of mV/decade or mV/dB. For the ADL5304 the default configuration 200 mV/decade (10 mV/dB). Y Logarithmic Intercept Logarithmic intercept extrapolated value representing ...

Page 17

... LOG Y 10 OPT Z ADL5304 operating in its default mode 3.95 fW for a diode having a responsivity Z = 0.2 V log (12.5 μW/3.95 fW) = 1.900 V LOG 10 ADL5304 ) to the output of is trimmed Y to 1.500 V, OFS has a value LOG is always above LOG (8) ) flows ( (10) may be written as (11 ...

Page 18

... FET amp design; the key limitation in the speed at low currents. Figure simplified schematic of the front-end section of the ADL5304. The numerator current, I INUM pin. The voltage at this node is equal to that on the two adjacent guard pins, VSM2 and IDEN, differing only by the offset ...

Page 19

... The theoretical noise and mV/dB, and in the ADL5304, this is increased to a slope mV/dB at the VLOG pin. Therefore, the noise at VLOG, predicted by Equation 22, is multiplied by a factor of 3.33 Secondary sources of noise, mostly in the analog divider used ...

Page 20

... COMM NMFS VNEG DNFS 8 VSM4 VDEN INDN 0.1µF DUT 5V BUFFER –9V 7805 – – = 100 pA, I NUM ADL5304 C1N ). LOG ) NUM C1D Rev Page R&S FSEA30 SPECTRUM ANALYZER 20MHz TO 3.5GHz INPUT COAX SHIELD BIASED TO VLOG DC LEVEL DUT 5V 2VLT VPOS DCBI 28 17 ...

Page 21

... VSMx pins are grounded, the DCBI and INPS pins must also be grounded. VSM1 FROM 2.0V V VSM2 REF PD SHIELD INUM IDEN SHIELD IREF VSM3 VSM4 Figure 50. PD Bias with V Rev Page ADL5304 FROM 1.5V VREF IMON VNUM 30 32 MONITOR AND PD BIAS 2 (1.1× NUM 1. 100nA Q1 ...

Page 22

... IDEN pin to provide the denominator current The choice of 100 nA places it in the DEN middle of the range. I REF input to the INUM pin and thereby invert the basic log response of the ADL5304 increases with increasing I DEN REF LOG ...

Page 23

... VNUM FROM 1.5V VREF 30 32 MONITOR AND PD BIAS 2 (1.1× VSM1 NUM R MNTR 3 VSM2 Q3 PD 100nA SHIELD Q1 INUM 4 IDEN 5 SHIELD Q2 6 IREF 7 VSM3 8 VSM4 9 VDEN Figure 53. Simple Slope Inversion Method ADL5304 (A) V (V) OFS 1.5 1.5 2.0 2.5 1.5 1.5 1.5 1.333 INNM 31 V NUM TEMP COMP V DEN 10 INDN ...

Page 24

... ADL5304 Log Ratio Operation Because the ADL5304 has two equal inputs, I ratio operation is possible. The only difference between I and I is that the I current derives from the I DEN MON allows adaptive photodiode bias at this input only. Assuming that the ratio I /I can, in general, be either greater or less ...

Page 25

... Data Sheet APPLICATIONS INFORMATION USING THE ADL5304 The basic connections for single-supply operation are shown in Figure 55. Supply decoupling is not critical and the suggested values are conservative; however recommended that a ferrite bead be placed in the supply lines together with a 0.1 μF decoupling capacitor. Ferrite beads are preferable to resistors because they do not produce a dc voltage drop that can affect reference levels ...

Page 26

... Figure 57. Increased Time Scale to Show Measurements Down to I USING A NEGATIVE SUPPLY > 10 kΩ. LOAD In most applications of the ADL5304, a single supply is adequate. A single supply also provides the lowest power operation. Dual supplies are needed if the user wants to bias the anode of the photodiode at ground, as was shown in Figure 50. ...

Page 27

... Data Sheet EVALUATION BOARD SCHEMATIC AND SILKSCREENS Figure 58. Evaluation Board Schematic Rev Page ADL5304 09459-202 ...

Page 28

... ADL5304 Figure 59. Evaluation Board, Primary Side Figure 60. Evaluation Board, Secondary Side Rev Page Data Sheet ...

Page 29

... Evaluation Board Rev Page 0.60 MAX PIN 1 INDICATOR 2.85 EXPOSED 2.70 SQ PAD (BOTTOM VIEW) 2. 0.20 MIN 3.50 REF FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. Ordering Quantity Package Option 250 CP-32-8 1500 CP-32-8 5000 CP-32-8 ADL5304 ...

Page 30

... ADL5304 NOTES Rev Page Data Sheet ...

Page 31

... Data Sheet NOTES Rev Page ADL5304 ...

Page 32

... ADL5304 NOTES ©2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D09459-0-9/11(0) Rev Page Data Sheet ...

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