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參數資料
| 型號： | AD8362-EVAL |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | 50 Hz to 2.7 GHz 60 dB TruPwr⑩ Detector |
| 中文描述： | 50赫茲到2.7 GHz 60分貝TruPwr⑩探測器 |
| 文件頁數： | 21/36頁 |
| 文件大小： | 700K |
| 代理商： | AD8362-EVAL |
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AD8362
MAIN MODES OF OPERATION
Both measurement and controller modes are supported by the
AD8362. Typical connections for the measurement mode,
which may also be viewed as the rms voltmeter mode, are also
illustrated in Figure 48. The output, VOUT, is proportional to
the logarithm of the rms magnitude of the input signal (that is,
a linear-on-dB response). When used in an accurately known
system impedance (but only then), the output is a scaled decibel
measurement of the power represented by the input voltage.
Rev. B | Page 21 of 36
The choice of the capacitances C
CPL
, C
DEC
, CHPF, and CLPF
depends on the lowest frequency to be included in the
measurement spectrum. The default values shown support
operation down to 100 Hz. Using a large enough value of CLPF
(10 μF) to ensure sufficient filtering at this low input frequency,
the response time is approximately 20 ms over most of the
dynamic range. In high frequency applications, this capacitor is
much smaller and is usually chosen to minimize the response
time, consistent with well-behaved, large-signal behavior. In this
figure, CHPF is also shown as 10 μF, to lower the high-pass
corner to about 90 Hz. However, no capacitor will be needed
here in most HF applications since the internally set high-pass
corner is at about 2 MHz.
Comparing the controller mode illustrated in Figure 49, the
AD8362 is used here to monitor the output of a variable gain
(or variable output power) signal processing element, frequently
a power amplifier, and adjust its output to a desired target value
(the setpoint) under the control of VSET. In this mode, its
function is somewhat like an RF comparator. With the path
from VOUT to VSET broken, any input larger than the
corresponding setpoint causes VOUT to rail to its maximum
value (which might loosely be viewed as a logic high). For
inputs smaller than the setpoint, the controller’s output falls to a
near-ground level (logic low). Using the AD8362 simply as a
threshold detector, this viewpoint may be useful, but in most
applications, it is an oversimplification. The AD8362 invariably
operates with the control loop closed, either locally with VOUT
connected to VSET (as in measurement mode), or globally via
some external nonlinear element (as in controller mode).
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
COMM
CHPF
DECL
INHI
INLO
DECL
PWDN
COMM
ACOM
VREF
VTGT
VPOS
VOUT
VSET
ACOM
CLPF
1nF
V
RAIL-TO-RAIL
CONTROL OUTPUT
SETPOINT INPUT
0V–3.5V
AD8362
SIGNAL INPUT
Z = 2
×
100
1mV – 1V rms
THIS CONNECTION
SETS CHIP-ENABLE
1nF
300pF
V
S
+5V nom, @ 24mA
0.1
μ
F
3.3
C
CPL
1nF
NC
NO CONNECTION
FOR f >10MHz
0
Figure 49. Basic Controller Mode Connections
Controller mode operation is more closely analogous to that of
a classical proportional/integral/derivative (PID) loop. The
error corresponding to the decibel deviation from the setpoint
is integrated by current into a capacitor (the sum of the internal
and external capacitance CLPF) until such deviation is nulled.
This action provides the fundamental proportional part of the
loop response (although VOUT has decibel scaling). The Q of
this system can be adjusted to minimize the loop response time
by including a resistor in series with CLPF, generating a
transmission zero, which provides the derivative term of a
standard PID loop.
As a simple example, assume that the AD8362 operates at an
input power level of 20 dBm re: 50 . Connected in the
measurement mode, it generates a VOUT of 2.00 V, because this
input is +40 dB above the intercept at 60 dBm and is scaled to
50 mV/dB. Rearranged to the controller mode with exactly this
voltage now externally applied to the VSET pin, the loop forces
VOUT to the control voltage required by the gain element to
provide a power sample of 20 dBm.
Of course, any control loop of this sort operates correctly
only if VSET corresponds to a power level (or a small sample of
such) that can actually be provided by the external gain element.
When this is a power amplifier, including the required amount
of RF attenuation ensures this condition. In certain instrument-
ation situations, it may be necessary to provide some low noise
gain ahead of the AD8362’s input.
These two primary modes of use are discussed in more detail,
with emphasis on practical considerations.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| AD8362-EVALZ | 功能描述:BOARD EVAL FOR AD8362 RoHS:是 類別:RF/IF 和 RFID >> RF 評估和開發套件，板 系列:TruePower™ 標準包裝:1 系列:- 類型:GPS 接收器 頻率:1575MHz 適用于相關產品:- 已供物品:模塊 其它名稱:SER3796 |
| AD8363 | 制造商:AD 制造商全稱:Analog Devices 功能描述:50 Hz to 6 GHz, 50 dB TruPwr? Detector |
| AD8363_09 | 制造商:AD 制造商全稱:Analog Devices 功能描述:50 Hz to 6 GHz, 50 dB TruPwr? Detector |
| AD8363ACPZ-R2 | 制造商:Analog Devices 功能描述:TRUE RMS PWR DETECTOR 24LFCSP EP - Tape and Reel |
| AD8363ACPZ-R7 | 功能描述:IC DETECTOR RF/IF TRUPWR 16LFCSP RoHS:是 類別:RF/IF 和 RFID >> RF 檢測器 系列:- 產品變化通告:Product Discontinuation 15/May/2006 標準包裝:3,000 系列:- 頻率:100MHz ~ 2GHz RF 型:手機，GSM，DCS，PCS 輸入范圍:- 精確度:- 電源電壓:2.7 V ~ 5.5 V 電流 - 電源:300µA 包裝:帶卷 (TR) 封裝/外殼:SC-74，SOT-457 其它名稱:NCS5000SNT1GOS |
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