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參數(shù)資料
| 型號(hào)： | ADL5306ACPZ-R2 |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 模擬信號(hào)調(diào)理 |
| 英文描述： | SPECIALTY ANALOG CIRCUIT, QCC16 |
| 封裝： | 3 X 3 MM, MO-220VEED-2, LFCSP-16 |
| 文件頁數(shù)： | 2/16頁 |
| 文件大?。?/td> | 1015K |
| 代理商： | ADL5306ACPZ-R2 |
ADL5306
Rev. 0 | Page 10 of 16
It is apparent that this output should be zero for IPD = IREF, and
would need to swing negative for smaller values of input
current. To avoid this, IREF would need to be as small as the
smallest value of IPD. In the ADL5306, an internal offset voltage
is added to VLOG to shift it upward by 0.8 V. This moves the
intercept to the left by four decades, from 10 A to 1 nA:
ILOG = IY log10(IPD / IINTC)
(4)
where IINTC is the operational / value of the intercept current.
Since values of IPD < IINTC result in a negative VLOG, a negative
supply of sufficient value is required to accommodate this
situation (discussed later).
The voltage VLOG is generated by applying ILOG to an internal
resistance of 4.55 k, formed by the parallel combination of a
6.69 k resistor to ground and the 14.2 k resistor to the
internal 2.5 V reference. At the VLOG pin, the output current
ILOG generates a voltage of
VLOG = ILOG × 4.55 k
= 44 A × 4.55 k × log10 (IPD / IREF)
(5)
= VY log10 (IPD / IREF)
where VY = 200 mV/decade or 10 mV/dB. Note that any
resistive loading on VLOG will lower this slope and will result
in an overall scaling uncertainty due to the variability of the on-
chip resistors. Consequently, this practice is not recommended.
VLOG may also swing below ground when dual supplies (VP and
VN) are used. When VN =
-0.5 V or more negative, the input
pins INPT and IREF may be positioned at ground level simply
by grounding VSUM.
MANAGING INTERCEPT AND SLOPE
As previously noted, the internally generated 2.5 V bias
combines with the on-chip resistors to introduce an accurate
offset voltage of 0.8 V at the VLOG pin, equivalent to four
decades. This results in a logarithmic transfer function that can
be written as
VLOG = VY log10 (104 × IPD / IREF)= VY log10 (IPD / IINTC)
(6)
where IINTC = IREF /104
Thus, the effective intercept current, IINTC, is only one ten-
thousandth of IREF, corresponding to 10 nA when using the
recommended value of IREF = 100 A.
The slope can be reduced by attaching a resistor to the VLOG
pin. This is strongly discouraged because the on-chip resistors
will not ratio correctly to the added resistance. Also, it is rare
that one would wish to lower the basic slope of 10 mV/dB; if
this is necessary, it should be done at the low impedance output
of the buffer, which is provided to avoid such miscalibration
and allow higher slopes to be used.
The ADL5306 buffer is essentially an uncommitted op amp
with rail-to-rail output swing, good load driving capabilities,
and a unity-gain bandwidth of >20 MHz. In addition to
allowing the introduction of gain using standard feedback
networks, thereby increasing the slope voltage, VY, the buffer
can be used to implement multipole low-pass filters, threshold
detectors, and a variety of other functions. For more details, see
the AD8304 Data Sheet.
RESPONSE TIME AND NOISE CONSIDERATIONS
The response time and output noise of the ADL5306 are
fundamentally a function of the signal current IPD. For small
currents, the bandwidth is proportional to IPD. The output’s low
frequency voltage-noise spectral density is a function of IPD, and
increases for small values of IREF. For details of noise and
bandwidth performance of translinear log amps, see the
AD8304 Data Sheet.
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| ADL5306ACPZ-REEL7 | 功能描述:IC CONV LOGARITHMIC 60DB 16LFCSP RoHS:是 類別:集成電路 (IC) >> 線性 - 放大器 - 專用 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:60 系列:- 類型:可變?cè)鲆娣糯笃?應(yīng)用:CATV 安裝類型:表面貼裝 封裝/外殼:20-WQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:20-TQFN-EP（5x5） 包裝:托盤 |
| ADL5306-EVAL | 制造商:Analog Devices 功能描述:Evaluation Board For IC Log Amp Single 5.5V 制造商:Analog Devices 功能描述:LOG AMP SGL 5.5V - Bulk |
| ADL5310 | 制造商:AD 制造商全稱:Analog Devices 功能描述:120 dB Range (3 nA to 3 mA) Dual Logarithmic Converter |
| ADL5310ACP | 制造商:Rochester Electronics LLC 功能描述:LOGARITHMIC CONVERTER - Bulk |
| ADL5310ACP-R2 | 功能描述:IC LOGARITHMIC CONV DUAL 24LFCSP RoHS:否 類別:集成電路 (IC) >> 線性 - 放大器 - 專用 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:60 系列:- 類型:可變?cè)鲆娣糯笃?應(yīng)用:CATV 安裝類型:表面貼裝 封裝/外殼:20-WQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:20-TQFN-EP（5x5） 包裝:托盤 |
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