AD8361ARM

更新时间： 2024-01-12 18:58:55

品牌	Logo	应用领域
亚德诺 - ADI		/
页数	文件大小	规格书
16页	307K
描述
LF to 2.5 GHz TruPwr⑩ Detector

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AD8361ARM 技术参数

是否无铅：	不含铅	是否Rohs认证：	符合
生命周期：	Obsolete	零件包装代码：	SOIC
包装说明：	MO-178-AB, SOT-23, 6 PIN	针数：	6
Reach Compliance Code：	not_compliant	ECCN代码：	5A991.B
HTS代码：	8542.39.00.01	风险等级：	5.08
Is Samacsys：	N	模拟集成电路 - 其他类型：	ANALOG CIRCUIT
JESD-30 代码：	R-PDSO-G6	JESD-609代码：	e3
长度：	2.9 mm	功能数量：	1
端子数量：	6	最高工作温度：	85 °C
最低工作温度：	-40 °C	封装主体材料：	PLASTIC/EPOXY
封装代码：	LSSOP	封装形状：	RECTANGULAR
封装形式：	SMALL OUTLINE, LOW PROFILE, SHRINK PITCH	峰值回流温度（摄氏度）：	260
认证状态：	Not Qualified	座面最大高度：	1.45 mm
最大供电电压 (Vsup)：	5.5 V	最小供电电压 (Vsup)：	2.7 V
标称供电电压 (Vsup)：	3 V	表面贴装：	YES
技术：	BIPOLAR	温度等级：	INDUSTRIAL
端子面层：	MATTE TIN	端子形式：	GULL WING
端子节距：	0.95 mm	端子位置：	DUAL
处于峰值回流温度下的最长时间：	40	宽度：	1.6 mm
Base Number Matches：	1

AD8361ARM 数据手册

AD8361

eventual loss of square-law conformance. Consequently, the top

end of their response range occurs at a fairly large input level

(about 700 mV rms) while preserving a reasonably accurate

square-law response. The maximum usable range is, in practice,

limited by the output swing. The rail-to-rail output stage can

swing from a few millivolts above ground to less than 100 mV

below the supply. An example of the output induced limit: given

a gain of 7.5 and assuming a maximum output of 2.9 V with a 3 V

supply; the maximum input is (2.9 V rms)/7.5 or 390 mV rms.

CIRCUIT DESCRIPTION

The AD8361 is an rms-responding (mean power) detector pro-

viding an approach to the exact measurement of RF power that

is basically independent of waveform. It achieves this function

through the use of a proprietary technique in which the outputs

of two identical squaring cells are balanced by the action of a

high-gain error ampliﬁer.

The signal to be measured is applied to the input of the ﬁrst

squaring cell, which presents a nominal (LF) resistance of 225 Ω

between the pin RFIN and COMM (connected to the ground

plane). Since the input pin is at a bias voltage of about 0.8 V

above ground, a coupling capacitor is required. By making this

an external component, the measurement range may be extended

to arbitrarily low frequencies.

Filtering

An important aspect of rms-dc conversion is the need for

averaging (the function is root-MEAN-square). For complex RF

waveforms such as occur in CDMA, the ﬁltering provided by

the on-chip low-pass ﬁlter, while satisfactory for CW signals above

100 MHz, will be inadequate when the signal has modulation

components that extend down into the kilohertz region. For this

reason, the FLTR pin is provided: a capacitor attached between

this pin and VPOS can extend the averaging time to very low

frequencies.

The AD8361 responds to the voltage, V_IN, at its input, by squaring

this voltage to generate a current proportional to V_INsquared.

This is applied to an internal load resistor, across which is con-

nected a capacitor. These form a low-pass ﬁlter, which extracts

the mean of V_INsquared. Although essentially voltage-responding,

the associated input impedance calibrates this port in terms of

equivalent power. Thus 1 mW corresponds to a voltage input of

447 mV rms. In the Application section it is shown how to match

this input to 50 Ω.

Offset

An offset voltage can be added to the output (when using the

micro_SOIC version) to allow the use of A/D converters whose

range does not extend down to ground. However, accuracy at

the low end will be degraded because of the inherent error in this

added voltage. This requires that the pin IREF (internal reference)

should be tied to VPOS and SREF (supply reference) to ground.

The voltage across the low-pass ﬁlter, whose frequency may

be arbitrarily low, is applied to one input of an error-sensing

ampliﬁer. A second identical voltage-squaring cell is used to

close a negative feedback loop around this error ampliﬁer.

This second cell is driven by a fraction of the quasi-dc output

voltage of the AD8361. When the voltage at the input of the

second squaring cell is equal to the rms value of V_IN, the loop

is in a stable state, and the output then represents the rms value of

the input. The feedback ratio is nominally 0.133, making the

rms-dc conversion gain ×7.5, that is

In the IREF mode, the intercept is generated by an internal

reference cell, and is a ﬁxed 350 mV, independent of the supply

voltage. To enable this intercept, IREF should be open-circuited,

and SREF should be grounded.

In the SREF mode, the voltage is provided by the supply. To

implement this mode, tie IREF to VPOS and SREF to VPOS. The

offset is then proportional to the supply voltage, and is 400 mV

for a 3 V supply and 667 mV for a 5 V supply.

V_OUT= 7.5 × V_INrms

By completing the feedback path through a second squaring cell,

identical to the one receiving the signal to be measured, several

beneﬁts arise. First, scaling effects in these cells cancel; thus, the

overall calibration may be accurate, even though the open-loop

response of the squaring cells taken separately need not be.

Note that in implementing rms-dc conversion, no reference

voltage enters into the closed-loop scaling. Second, the tracking

in the responses of the dual cells remains very close over tempera-

ture, leading to excellent stability of calibration.

USING THE AD8361

Basic Connections

Figures 32, 33, and 34 show the basic connections for the

micro_SOIC version AD8361 in its three operating modes. In all

modes, the device is powered by a single supply of between 2.7 V

and 5.5 V. The VPOS pin is decoupled using 100 pF and 0.01 µF

capacitors. The quiescent current of 1.1 mA in operating mode

can be reduced to 1 µA by pulling the PWDN pin up to VPOS.

A 75 Ω external shunt resistance combines with the ac-coupled

input to give an overall broadband input impedance near 50 Ω.

Note that the coupling capacitor must be placed between the in-

put and the shunt impedance. Input impedance and input coupling

are discussed in more detail below.

The squaring cells have very wide bandwidth with an intrinsic

response from dc to microwave. However, the dynamic range

of such a system is fairly small, due in part to the much larger

dynamic range at the output of the squaring cells. There are

practical limitations to the accuracy with which very small error

signals can be sensed at the bottom end of the dynamic range,

arising from small random offsets; these set the limit to the

attainable accuracy at small inputs.

The input coupling capacitor combines with the internal input

resistance (Figure 13) to give a high-pass corner frequency

given by the equation

On the other hand, the squaring cells in the AD8361 have

a “Class-AB” aspect; the peak input is not limited by their

quiescent bias condition, but is determined mainly by the

f_{3 dB}

2 π × C_C× R_IN

REV. A

–9–

1...6 7 8910 11 12...16

中文翻译

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与AD8361ARM相关器件

型号	品牌	描述	获取价格	数据表
AD8361ARM-REEL	ADI	LF to 2.5 GHz TruPwr⑩ Detector	获取价格
AD8361ARM-REEL7	ADI	LF to 2.5 GHz TruPwr⑩ Detector	获取价格
AD8361ARMZ	ADI	LF to 2.5 GHz TruPwr Detector	获取价格
AD8361ARMZ1	ADI	LF to 2.5 GHz TruPwr? Detector	获取价格
AD8361ARMZ-REEL	ADI	LF to 2.5 GHz TruPwr? Detector	获取价格
AD8361ARMZ-REEL7	ADI	LF to 2.5 GHz TruPwr? Detector	获取价格
AD8361ART	ADI	LF to 2.5 GHz TruPwr Detector	获取价格
AD8361ART-EVAL	ADI	LF to 2.5 GHz TruPwr⑩ Detector	获取价格
AD8361ART-REEL	ADI	LF to 2.5 GHz TruPwr⑩ Detector	获取价格
AD8361ART-REEL7	ADI	LF to 2.5 GHz TruPwr⑩ Detector	获取价格
AD8361ARTZ-REEL	ADI	SPECIALTY ANALOG CIRCUIT, PDSO6, MO-178-AB, SOT-23, 6 PIN	获取价格
AD8361ARTZ-REEL7	ADI	SPECIALTY ANALOG CIRCUIT, PDSO6, MO-178-AB, SOT-23, 6 PIN	获取价格
AD8361ARTZ-RL7	ADI	LF to 2.5 GHz TruPwr? Detector	获取价格
AD8361-EVAL	ADI	LF to 2.5 GHz TruPwr⑩ Detector	获取价格
AD8361-EVALZ	ADI	LF to 2.5 GHz TruPwr Detector	获取价格
AD8362	ADI	50 Hz to 2.7 GHz 60 dB TruPwr⑩ Detector	获取价格
AD8362_1	ADI	50 Hz to 3.8 GHz 65 dB TruPwr? Detector	获取价格
AD8362ARU	ADI	50 Hz to 2.7 GHz 60 dB TruPwr⑩ Detector	获取价格
AD8362ARU-REEL	ADI	50 Hz to 3.8 GHz 65 dB TruPwr? Detector	获取价格
AD8362ARU-REEL7	ADI	50 Hz to 2.7 GHz 60 dB TruPwr⑩ Detector	获取价格

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