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| 型号： | AD8313 |
| 厂商： | Analog Devices, Inc. |
| 英文描述： | 0.1 GHz－2.5 GHz,70dB Logarithmic Detector/Controller(频率为0.1 GHz－2.5 GHz,增益为70dB的对数检测器/控制器) |
| 中文描述： | 0.1千兆赫，2.5千兆赫，70dB的对数检测器/控制器（频率为0.1千兆赫，2.5千兆赫，增益为70dB的的对数检测器/控制器） |
| 文件页数： | 14/16页 |
| 文件大小： | 278K |
| 代理商： | AD8313 |
AD8313
–14–
REV. 0
In addition to providing current gain, the resistor/potentiometer
combination between VSET and the emitter of the transistor
increases the log slope to as much as 45 mV/dB, at maximum
resistance. This will give an output voltage of 4 V for a 0 dBm
input. If no increase in the log slope is required, VSET can be
connected directly to the emitter of the transistor.
Effect of Waveform Type On Intercept
Although it is specified for input levels in dBm (dB relative to
1 mW), the AD8313 fundamentally responds to voltage and not
to power. A direct consequence of this characteristic is that
input signals of equal rms power but differing crest factors will
produce different results at the log amp’s output.
The effect of different signal waveforms is to vary the effec-
tive value of the log amp’s intercept upwards or downwards.
Graphically, this looks like a vertical shift in the log amp’s trans-
fer function. The device’s logarithmic slope, however, is in
principle not affected. For example, consider the case of the
AD8313 being alternately fed from a continuous wave and a
single CDMA channel of the same rms power. The AD8313’s
output voltage will differ by the equivalent of 3.55 dB (64 mV)
over the complete dynamic range of the device (the output for a
CDMA input being lower).
Table III shows the correction factors that should be applied to
measure the rms signal strength of a various signal types. A
continuous wave input is used as a reference. To measure the
rms power of a square-wave, for example, the mV equivalent
of the dB value given in the table (18 mV/dB times 3.01 dB)
should be subtracted from the output voltage of the AD8313.
Table III. Shift in AD8313 Output for Signals with Differing
Crest Factors
Correction Factor
(Add to Output Reading)
Signal Type
CW Sine Wave
Square Wave or DC
Triangular Wave
GSM Channel (All Time Slots On)
CDMA Channel
PDC Channel (All Time Slots On)
Gaussian Noise
0 dB
–3.01 dB
+0.9 dB
+0.55 dB
+3.55 dB
+0.58 dB
+2.51 dB
EVALUATION BOARD
Schematic and Layout
Figure 44 shows the schematic of the evaluation board that was
used to characterize the AD8313. Note that uninstalled compo-
nents are drawn in as dashed.
This is a 3-layer board (signal, ground and power), with a Duroid
dielectric (RT 5880, h = 5 mil,
ε
R
= 2.2). FR4 can also be used,
but microstrip dimensions must be recalculated because of the
different dielectric constant and board height. The trace layout
and silkscreen of the signal and power layers are shown in Fig-
ures 40 to 43. A detail of the PCB footprint for the
μ
SOIC
package and the pads for the matching components are shown
in Figure 45.
The vacant portions of the signal and power layers are filled out
with ground plane for general noise suppression. To ensure a
low impedance connection between the planes, there are mul-
tiple through-hole connections to the RF ground plane. While
the ground planes on the power and signal planes are used as
general purpose ground returns, any RF grounds related to the
input matching network (e.g., C2) are returned directly to the
RF internal ground plane.
General Operation
The board should be powered by a single supply in the range,
+2.7 V to +5.5 V. The power supply to each of the VPOS pins
is decoupled by a 10
resistor and a 0.1
μ
F capacitor.
The two signal inputs are ac-coupled using 680 pF high quality
RF capacitors (C1, C2). A 53.6
resistor across the differential
signal inputs (INHI, INLO) combines with the internal 900
input impedance to give a broadband input impedance of 50.6
.
This termination is not optimal from a noise perspective due to
the Johnson noise of the 53.6
resistor. Neither does it take
account for the AD8313’s reactive input impedance or of the
decrease over frequency of the resistive component of the input
impedance. However, it does allow evaluation of the AD8313
over its complete frequency range without having to design
multiple matching networks.
For optimum performance, a narrowband match can be imple-
mented by replacing the 53.6
resistor (labeled L/R) with an
RF inductor and replacing the 680 pF capacitors with appropri-
ate values. The section on Input Matching includes a table of
recommended values for selected frequencies and explains the
method of calculation.
Switch 1 is used to select between power-up and power-down
modes. Connecting the PWDN pin to ground enables normal
operation of the AD8313. In the opposite position, the PWDN
pin can either be driven externally (SMA connector labeled
EXT ENABLE) to either device state or allowed to float to a
disabled device state.
The evaluation board ships with the AD8313 configured to
operate in RSSI measurement mode, the logarithmic output
appearing on the SMA connector labeled VOUT. This mode is
set by the 0
resistor (R11), which shorts the VOUT and
VSET pins to each other.
Varying the Logarithmic Slope
The slope of the AD8313 can be increased from its nominal
value of 18 mV/dB to a maximum of 40 mV/dB by removing
R11, the 0
resistor, which shorts VSET to VOUT. VSET and
VOUT are now connected through a 20 k
potentiometer.
Operating in Controller Mode
To put the AD8313 into controller mode, R7 and R11 should
be removed, breaking the link between VOUT and VSET. The
VSET pin can then be driven externally via the SMA connector
labeled EXT VSET IN ADJ.
Increasing Output Current
To increase the output current of V
OUT
, set both R3 and R11 to
0
and install potentiometer R4 (1 k
to 5 k
).
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| AD8314ARM | 100 MHz-2500 MHz 45 dB RF Detector/Controller |
| AD8314ARM-REEL | 100 MHz-2500 MHz 45 dB RF Detector/Controller |
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| AD8314 | 100 MHz-2500 MHz 45 dB RF Detector/Controller |
| AD8314-EVAL | 100 MHz-2500 MHz 45 dB RF Detector/Controller |
相关代理商/技术参数 |
参数描述 |
|---|---|
| AD8313_04 | 制造商:AD 制造商全称:Analog Devices 功能描述:0.1 GHz to 2.5 GHz 70 dB Logarithmic Detector/Controller |
| AD8313ARM | 功能描述:IC LOGARTIHMIC AMP 70DB 8-MSOP RoHS:否 类别:RF/IF 和 RFID >> RF 检测器 系列:- 产品变化通告:Product Discontinuation 15/May/2006 标准包装:3,000 系列:- 频率:100MHz ~ 2GHz RF 型:手机，GSM，DCS，PCS 输入范围:- 精确度:- 电源电压:2.7 V ~ 5.5 V 电流 - 电源:300µA 包装:带卷 (TR) 封装/外壳:SC-74，SOT-457 其它名称:NCS5000SNT1GOS |
| AD8313ARM | 制造商:Analog Devices 功能描述:Logarithmic Amplifier IC |
| AD8313ARM-REEL | 功能描述:IC LOG DETECTOR/CTRLR 8-MSOP RoHS:否 类别:RF/IF 和 RFID >> RF 检测器 系列:- 产品变化通告:Product Discontinuation 15/May/2006 标准包装:3,000 系列:- 频率:100MHz ~ 2GHz RF 型:手机，GSM，DCS，PCS 输入范围:- 精确度:- 电源电压:2.7 V ~ 5.5 V 电流 - 电源:300µA 包装:带卷 (TR) 封装/外壳:SC-74，SOT-457 其它名称:NCS5000SNT1GOS |
| AD8313ARM-REEL7 | 功能描述:IC LOG DETECTOR/CTRLR 8-MSOP RoHS:否 类别:RF/IF 和 RFID >> RF 检测器 系列:- 产品变化通告:Product Discontinuation 15/May/2006 标准包装:3,000 系列:- 频率:100MHz ~ 2GHz RF 型:手机，GSM，DCS，PCS 输入范围:- 精确度:- 电源电压:2.7 V ~ 5.5 V 电流 - 电源:300µA 包装:带卷 (TR) 封装/外壳:SC-74，SOT-457 其它名称:NCS5000SNT1GOS |
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