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參數(shù)資料
| 型號(hào)： | AD648KN |
| 廠商： | ANALOG DEVICES INC |
| 元件分類(lèi)： | 運(yùn)動(dòng)控制電子 |
| 英文描述： | Dual Precision, Low Power BiFET Op Amp |
| 中文描述： | DUAL OP-AMP, 1500 uV OFFSET-MAX, 1 MHz BAND WIDTH, PDIP8 |
| 封裝： | MINI, PLASTIC, DIP-8 |
| 文件頁(yè)數(shù)： | 10/12頁(yè) |
| 文件大?。?/td> | 335K |
| 代理商： | AD648KN |
AD648
REV. C
–10–
LOG RAT IO AMPLIFIE R
Log ratio amplifiers are useful for a variety of signal condition-
ing applications, such as linearizing exponential transducer out-
puts and compressing analog signals having a wide dynamic
range. T he AD648’s picoamp level input current and low input
offset voltage make it a good choice for the front-end amplifier
of the log ratio circuit shown in Figure 30. T his circuit produces
an output voltage equal to the log base 10 of the ratio of the in-
put currents I
1
and I
2
. Resistive inputs R1 and R2 are provided
for voltage inputs.
Input currents I
1
and I
2
set the collector currents of Q1 and Q2,
a matched pair of logging transistors. Voltages at points A and B
are developed according to the following familiar diode equation:
V
BE
=
(
kT/q
)
ln
(
I
C
/
I
ES
)
In this equation, k is Boltzmann’s constant, T is absolute tem-
perature, q is an electron charge, and I
ES
is the reverse satura-
tion current of the logging transistors. T he difference of these
two voltages is taken by the subtractor section and scaled by a
factor of approximately 16 by resistors R9, R10 and R8. T em-
perature compensation is provided by resistors R8 and R15,
which have a positive 3500 ppm/
°
C temperature coefficient.
T he transfer function for the output voltage is:
V
OUT
=
1
V log
10
(I
2
/I
1
)
Frequency compensation is provided by R11, R12, C1, and C2.
Small signal bandwidth is approximately 300 kHz at input cur-
rents above 100
μ
A and will proportionally decrease with lower
signal levels. D1, D2, R13, and R14 compensate for the effects
of the two logging transistors’ ohmic emitter resistance.
T o trim this circuit, set the two input currents to 10
μ
A and ad-
just V
OUT
to zero by adjusting the potentiometer on A3. T hen
set I
2
to 1
μ
A and adjust the scale factor such that the output
voltage is 1 V by trimming potentiometer R10. Offset adjust-
ment for A1 and A2 is provided to increase the accuracy of the
voltage inputs.
T his circuit ensures a 1% log conformance error over an input
current range of 300 pA to l mA, with low level accuracy limited
by the AD648’s input current. T he low level input voltage accu-
racy of this circuit is limited by the input offset voltage and drift
of the AD648.
Figure 30. Precision Log Ratio Amplifier
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PDF描述 |
|---|---|
| AD648KR | Dual Precision, Low Power BiFET Op Amp |
| AD648S | Dual Precision, Low Power BiFET Op Amp |
| AD648SQ | Dual Precision, Low Power BiFET Op Amp |
| AD648T | Dual Precision, Low Power BiFET Op Amp |
| AD648SCHIPS | Dual Precision, Low Power BiFET Op Amp |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD648KN/+ | 制造商:未知廠家 制造商全稱(chēng):未知廠家 功能描述:Operational Amplifier |
| AD648KNZ | 功能描述:IC OPAMP BIFET 1MHZ DUAL LP 8DIP RoHS:是 類(lèi)別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 放大器類(lèi)型:通用 電路數(shù):4 輸出類(lèi)型:- 轉(zhuǎn)換速率:0.6 V/µs 增益帶寬積:1MHz -3db帶寬:- 電流 - 輸入偏壓:45nA 電壓 - 輸入偏移:2000µV 電流 - 電源:1.4mA 電流 - 輸出 / 通道:40mA 電壓 - 電源，單路/雙路(±):3 V ~ 32 V，±1.5 V ~ 16 V 工作溫度:0°C ~ 70°C 安裝類(lèi)型:表面貼裝 封裝/外殼:14-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:14-TSSOP 包裝:帶卷 (TR) 其它名稱(chēng):LM324ADTBR2G-NDLM324ADTBR2GOSTR |
| AD648KR | 制造商:Analog Devices 功能描述:OP Amp Dual GP ±18V 8-Pin SOIC N 制造商:Rochester Electronics LLC 功能描述:LOW POWER DUAL OP AMP IC - Bulk |
| AD648KR-REEL | 制造商:Analog Devices 功能描述:OP Amp Dual GP ±18V 8-Pin SOIC N T/R |
| AD648KR-REEL7 | 制造商:Analog Devices 功能描述:OP Amp Dual GP ±18V 8-Pin SOIC N T/R 制造商:Rochester Electronics LLC 功能描述:DUAL BIFET OP AMP IC - Tape and Reel |
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