參數(shù)資料
型號: AD648JN
廠商: ANALOG DEVICES INC
元件分類: 運動控制電子
英文描述: CAP X7R,0.1UF,50V,10%,0805
中文描述: DUAL OP-AMP, 3000 uV OFFSET-MAX, 1 MHz BAND WIDTH, PDIP8
封裝: MINI, PLASTIC, DIP-8
文件頁數(shù): 10/12頁
文件大?。?/td> 335K
代理商: AD648JN
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
相關(guān)PDF資料
PDF描述
AD648JR Dual Precision, Low Power BiFET Op Amp
AD648JR-REEL CAPACITOR 0805 X7R 10NF 100V 10%CAPACITOR 0805 X7R 10NF 100V 10%; CAPACITANCE:10NF; VOLTAGE RATING, DC:100V; CAPACITOR DIELECTRIC TYPE:CERAMIC MULTI-LAYER; SERIES:B37941; TOLERANCE, :10%; TOLERANCE, -:10%; TEMP, OP. MAX:125(DEGREE RoHS Compliant: Yes
AD648JR-REEL7 Dual Precision, Low Power BiFET Op Amp
AD648KR-REEL Dual Precision, Low Power BiFET Op Amp
AD648KR-REEL7 Dual Precision, Low Power BiFET Op Amp
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AD648JNZ 功能描述:IC OPAMP BIFET 1MHZ DUAL LP 8DIP RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 產(chǎn)品培訓(xùn)模塊:Differential Circuit Design Techniques for Communication Applications 標(biāo)準(zhǔn)包裝:1 系列:- 放大器類型:RF/IF 差分 電路數(shù):1 輸出類型:差分 轉(zhuǎn)換速率:9800 V/µs 增益帶寬積:- -3db帶寬:2.9GHz 電流 - 輸入偏壓:3µA 電壓 - 輸入偏移:- 電流 - 電源:40mA 電流 - 輸出 / 通道:- 電壓 - 電源,單路/雙路(±):3 V ~ 3.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-VQFN 裸露焊盤,CSP 供應(yīng)商設(shè)備封裝:16-LFCSP-VQ 包裝:剪切帶 (CT) 產(chǎn)品目錄頁面:551 (CN2011-ZH PDF) 其它名稱:ADL5561ACPZ-R7CT
AD648JNZKL1 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述:
AD648JR 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 制造商:Analog Devices 功能描述:IC OP-AMP DUAL BIFET
AD648JR-REEL 制造商:Analog Devices 功能描述:OP Amp Dual GP ±18V 8-Pin SOIC N T/R
AD648JR-REEL7 制造商:Analog Devices 功能描述:OP Amp Dual GP ±18V 8-Pin SOIC N T/R