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參數資料
| 型號： | AD8304-EVAL |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | 160 dB Range (100 pA -10 mA) Logarithmic Converter |
| 中文描述： | 160分貝范圍（100功率放大器-10毫安）對數轉換器 |
| 文件頁數： | 14/20頁 |
| 文件大小： | 4286K |
| 代理商： | AD8304-EVAL |
REV. A
–14–
AD8304
ACOM Pin, and does not normally go negative with regard to this
pin, but is free to do so. Therefore, a resistor from VLOG to the
negative supply can lower V
LOG
, thus raising the intercept. A more
accurate method for repositioning the intercept is described below.
INPUT – A
100p
10m
1n
10n
100n
1
10
100
1m
2.0
–2.0
E
1.5
0
–0.5
–1.0
–1.5
1.0
0.5
WITHOUT INTERCEPT ADJUST
WITH INTERCEPT ADJUST
V
NEG
= 0
V
NEG
= –0.5
V
NEG
= –3
Figure 11. Log Conformance (Linearity) vs. I
PD
for
Various Negative Supplies
APPLICATIONS
The AD8304 incorporates features that improve its usefulness in
both fiber optic supervisory applications and in more general ones.
To aid in the exploration of these possibilities, a SPICE macro-
model is provided and a versatile evaluation board is available.
The macromodel is shown in generalized schematic form (and thus
is independent of variations in SPICE programs) in Figure 12.
Q1, QM, and Q2 (here made equal in size) correspond to the
identical transistors in Figure 1. The model parameters for these
transistors are not critical; the default model provided in SPICE
libraries will be satisfactory. However, the AD8304 employs
compensation techniques to reduce errors caused by junction
resistances (notably, RB and RE) at high input currents. There-
fore, it is advisable to set these to zero. While this will not model
the AD8304 precisely, it is safer than using possibly high default
values for these parameters. The low current model parameters
may also need consideration. Note that no attempt is made to
capture either dynamic behavior or the effects of temperature in this
simple macromodel; scaling is correct for 27
°
C.
V
E4
V2
R1
R2
VLOG
7
5
C2
V
Q3
I1
IPD
IN
1
2
3
4
I1
I2
E3
E2
C1
6
RL
I1
C1
E1
V1
Q1
I2
Q2
I3
Q3
.MODEL
E2
E3
E4
V2
R1
C2
R2
RL
0
IN
2
1
IN
0
3
0
4
NPN
5
6
7
8
8
9
9
VLOG
IN
0
0
0
2
3
3
4
4
NPN
0
0
0
7
9
0
VLOG
0
DC
1.0N
IN
0.5
0
1
0
316.2
0
POLY (2)
POLY (2)
6 4 3 7 0 0, 0, 0, 0, 1
0.8
100
163P
4.9K
1000K
1 A
1
NPN
NPN
NPN
2 3 1 0 0, 0, 0, 0, 1
3K
Q2
Q1
100k
3k
+
Figure 12. Basic Macromodel
相關PDF資料 |
PDF描述 |
|---|---|
| AD8304ARU | 160 dB Range (100 pA -10 mA) Logarithmic Converter |
| AD8304ARU-REEL7 | 160 dB Range (100 pA -10 mA) Logarithmic Converter |
| AD8305 | 100 dB Range (10 nA to 1 mA) Logarithmic Converter |
| AD8305ACP | 100 dB Range (10 nA to 1 mA) Logarithmic Converter |
| AD8305ACP-REEL7 | 100 dB Range (10 nA to 1 mA) Logarithmic Converter |
相關代理商/技術參數 |
參數描述 |
|---|---|
| AD8304-EVALZ | 制造商:Analog Devices 功能描述:Evaluation Kit For 160 DB Range Logarithmic Converter 制造商:Analog Devices 功能描述:EVAL KIT FOR 160 DB RANGE (100 PA -10 MA) LOGARITHMIC CNVRTR - Bulk 制造商:Analog Devices 功能描述:EVAL LOGARITHMIC DECTECTOR AD8304 |
| AD8304XRU | 制造商:Analog Devices 功能描述: |
| AD8305 | 制造商:Analog Devices 功能描述:SP AMP LOG AMP SGL R-R O/P 6V/12V 16LFCSP EP - Bulk |
| AD8305_CSURF | 制造商:Analog Devices 功能描述: |
| AD8305ACP | 制造商:AD 制造商全稱:Analog Devices 功能描述:100 dB Range (10 nA to 1 mA) Logarithmic Converter |
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