AD8361 ,2.5 GHz TruPwr?DetectorApplications section.5SOT-23-6L operates in ground reference mode only.6The available output swing, ..
AD8361ARM ,LF to 2.5 GHz TruPwr⑩ DetectorLF to 2.5 GHz™aTruPwr DetectorAD8361
AD8361ARM. ,LF to 2.5 GHz TruPwr⑩ DetectorAPPLICATIONSMeasurement of CDMA, W-CDMA, QAM, OtherADDOFFSETComplex Modulation WaveformsBAND-GAPSRE ..
AD8361ARM-REEL ,LF to 2.5 GHz TruPwr⑩ DetectorApplications section.5SOT-23-6L operates in ground reference mode only.6The available output swing, ..
AD8361ARM-REEL7 ,LF to 2.5 GHz TruPwr⑩ DetectorFEATURES FUNCTIONAL BLOCK DIAGRAMSCalibrated RMS ResponseExcellent Temperature Stability micro_SOIC ..
AD8361ARMZ-REEL , LF to 2.5 GHz TruPwr™ Detector
ADP3330ART-2.85-RL ,High Accuracy Ultralow I(Q), 200 mA, SOT-23, anyCAP® Low Dropout RegulatorFEATURES FUNCTIONAL BLOCK DIAGRAMHigh Accuracy Over Line and Load: 60.7% @ +258C,61.4% Over Tempera ..
ADP3330ART-3 ,High Accuracy Ultralow IQ, 200 mA, SOT-23, anyCAP⑩ Low Dropout Regulatorspecifications apply to all voltage options except –2.5.Parameter Symbol Conditions Min Typ Max Uni ..
ADP3330ART-3.3 ,High Accuracy Ultralow IQ, 200 mA, SOT-23, anyCAP⑩ Low Dropout RegulatorSpecifications subject to change without notice.–2– REV. AADP3330ADP3330-2.5–
ADP3330ART-3.3 ,High Accuracy Ultralow IQ, 200 mA, SOT-23, anyCAP⑩ Low Dropout RegulatorAPPLICATIONSCellular TelephonesNotebook, Palmtop ComputersBattery Powered SystemsPCMCIA RegulatorBa ..
ADP3330ART-3.3-RL7 ,High Accuracy Ultralow I(Q), 200 mA, SOT-23, anyCAP® Low Dropout RegulatorSPECIFICATIONS (@ T = –408C to +858C, V = +7 V ,C = 0.47 mF, C = 0.47 mF,A IN IN OUT1, 2unless ot ..
ADP3330ART-3.3-RL7 ,High Accuracy Ultralow I(Q), 200 mA, SOT-23, anyCAP® Low Dropout RegulatorAPPLICATIONSCellular TelephonesNotebook, Palmtop ComputersBattery Powered SystemsPCMCIA RegulatorBa ..
AD8361
2.5 GHz TruPwr?Detector
REV.B
LF to 2.5 GHz
TruPwr™ Detector
FUNCTIONAL BLOCK DIAGRAMS
micro_SOIC
SOT-23-6L
FEATURES
Calibrated RMS Response
Excellent Temperature Stability
Up to 30 dB Input Range at 2.5 GHz
700 mV rms, 10 dBm re 50 � Maximum Input�0.25 dB Linear Response Up to 2.5 GHz
Single Supply Operation: 2.7 V to 5.5 V
Low Power:3.3 mW at 3 V Supply
Rapid Power-Down to Less than 1 �A
APPLICATIONS
Measurement of CDMA, W-CDMA, QAM, Other
Complex Modulation Waveforms
RF Transmitter or Receiver Power Measurement
PRODUCT DESCRIPTIONThe AD8361 is a mean-responding power detector for use in high-
frequency receiver and transmitter signal chains, up to 2.5GHz.
It is very easy to apply. It requires only a single supply between
2.7 V and 5.5 V, power supply decoupling capacitor and an
input coupling capacitor in most applications. The output is a
linear-responding dc voltage with a conversion gain of 7.5 V/Vrms.
An external filter capacitor can be added to increase the averag-
ing time constant.
Figure 1.Output in the Three Reference Modes, Supply 3 V,
Frequency 1.9 GHz (SOT-23-6L Package Ground Reference
Mode Only)
TruPwr is a trademark of Analog Devices, Inc.
The AD8361 is intended for true power measurement of simple
and complex waveforms. The device is particularly useful for
measuring high crest-factor (high peak-to-rms ratio) signals, such
as CDMA and W-CDMA.
The AD8361 has three operating modes to accommodate a
variety of analog-to-digital converter requirements:Ground referenced mode, in which the origin is zero;Internal reference mode, which offsets the output 350 mV
above ground;Supply reference mode, which offsets the output to VS/7.5.
The AD8361 is specified for operation from –40°C to +85°C and
is available in 8-lead micro_SOIC and 6-lead SOT packages.
It is fabricated on a proprietary high fT silicon bipolar process.
AD8361–SPECIFICATIONS
(TA = 25�C, VS = 3 V, fRF = 900 MHz, ground reference output mode, unless
otherwise noted.)NOTESOperation at arbitrarily low frequencies is possible; see Applications section.TPC 12 and Figure 10 show impedance versus frequency for the micro_SOIC and SOT respectively.Calculated using linear regression.Compensated for output reference temperature drift; see Applications section.SOT-23-6L operates in ground reference mode only.The available output swing, and hence the dynamic range, is altered by both supply voltage and reference mode; see Figures 5 and 6.Supply current is input level dependant; see TPC 11.
Specifications subject to change without notice.
ABSOLUTE MAXIMUM RATINGS1Supply Voltage VS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5 V
SREF, PWDN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V, VS
IREF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VS – 0.3 V, VS
RFIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 V rms
Equivalent Power re 50 Ω . . . . . . . . . . . . . . . . . . . 13 dBm
Internal Power Dissipation2 . . . . . . . . . . . . . . . . . . . . 200 mW
SOT-23-6L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 mW
micro_SOIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 mW
Maximum Junction Temperature . . . . . . . . . . . . . . . . . 125°C
Operating Temperature Range . . . . . . . . . . –40°C to +85°C
Storage Temperature Range . . . . . . . . . . . –65°C to +150°C
Lead Temperature Range (Soldering 60 sec) . . . . . . . . . 300°C
NOTESStresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.Specification is for the device in free air.
SOT-23-6L: θJA = 230°C/W; θJC = 92°C/W.
micro_SOIC: θJA = 200°C/W; θJC = 44°C/W.
CAUTIONESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000V readily
accumulate on the human body and test equipment and can discharge without detection. Although
PIN FUNCTION DESCRIPTIONS
SOT-23-6L
ORDERING GUIDE*Device branded as J3A.
AD8361
–Typical Performance CharacteristicsTPC 1.Output vs. Input Level, Frequencies 100 MHz,
900 MHz, 1900 MHz, and 2500 MHz, Supply 2.7 V, Ground
Reference Mode, micro_SOIC
INPUT – V rms
OUTPUT
Volts
0.60.70.8TPC 2.Output vs. Input Level, Supply 2.7 V, 3.0 V, 5.0 V,
and 5.5 V, Frequency 900 MHz
TPC 4.Error from Linear Reference vs. Input Level,
3 Sigma to Either Side of Mean, Sine Wave, Supply 3.0 V,
Frequency 900 MHz
TPC 5.Error from Linear Reference vs. Input Level,
3 Sigma to Either Side of Mean, Sine-Wave, Supply 5.0 V,
Frequency 900 MHz
INPUT – V rms
ERROR
dB
0.020.60.2
TPC 7.Error from CW Linear Reference vs. Input,
3 Sigma to Either Side of Mean, IS95 Reverse Link Signal,
Supply 3.0 V, Frequency 900 MHz
TPC 10.
3 Sigma to Either Side of Mean Sine Wave, Supply 3.0 V,
Frequency 1900 MHz, Temperature –40°C to +85°C
TPC 11.Supply Current vs. Input Level, Supplies 3.0 V,
and 5.0 V, Temperatures –40°C, +25°C, and +85°C
FREQUENCY – MHz5001000
SHUNT RESISTANCE
SHUNT CAPACITANCE
pF
1.8
AD8361
TEMPERATURE – �C
INTERCEPT CHANGE
Volts
–0.0580100TPC 13.Output Reference Change vs. Temperature,
Supply 3 V, Ground Reference Mode
TPC 14.Output Reference Change vs. Temperature,
Supply 3 V, Internal Reference Mode (micro_SOIC Only)
TPC 15.Output Reference Change vs. Temperature,
TPC 16.Conversion Gain Change vs. Temperature,
Supply 3 V, Ground Reference Mode, Frequency 900 MHz
TPC 17.Conversion Gain Change vs. Temperature,
Supply 3 V, Internal Reference Mode, Frequency 900 MHz
(micro_SOIC Only)
TPC 18.Conversion Gain Change vs. Temperature,
TPC 19.Output Response to Modulated Pulse Input
for Various RF Input Levels, Supply 3 V, Modulation
Frequency 900 MHz, No Filter Capacitor
TPC 20.Output Response to Modulated Pulse Input
for Various RF Input Levels, Supply 3 V, Modulation
Frequency 900 MHz, 0.01 µF Filter Capacitor
TPC 21.Hardware Configuration for Output Response to
Modulated Pulse Input
TPC 22.Output Response Using Power-Down Mode
for Various RF Input Levels, Supply 3 V, Frequency
900 MHz, No Filter Capacitor
TPC 23.Output Response Using Power-Down Mode
for Various RF Input Levels, Supply 3 V, Frequency
900 MHz, 0.01 µF Filter Capacitor
TPC 24.Hardware Configuration for Output Response
Using Power-Down Mode
AD8361TPC 25.Conversion Gain Change vs. Frequency, Supply
3 V, Ground Reference Mode, Frequency 100 MHz to
2500 MHz, Representative Device
TPC 26.Output Response to Gating On Power Supply,
for Various RF Input Levels, Supply 3 V, Modulation
Frequency 900 MHz, 0.01 µF Filter Capacitor
TPC 28.Conversion Gain Distribution Frequency
100 MHz, Supply 5 V, Sample Size 3000
TPC 29.Output Reference, Internal Reference Mode,
Supply 5 V, Sample Size 3000 (micro_SOIC Only)
CIRCUIT DESCRIPTIONThe 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.
The AD8361 responds to the voltage, VIN, at its input, by squaring
this voltage to generate a current proportional to VIN squared.
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 VIN squared. 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.
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 VIN, 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
VOUT = 7.5 × VIN rms
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.
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.
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
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.
FilteringAn 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.
OffsetAn 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.
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.
USING THE AD8361
Basic ConnectionsFigures 2, 3, and 4 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 2.7V and 5.5 V.
The VPOS pin is decoupled using 100 pF and 0.01µF 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
input and the shunt impedance. Input impedance and input cou-
pling are discussed in more detail below.
The input coupling capacitor combines with the internal input
resistance (Figure 3) to give a high-pass corner frequency
given by the equation
AD8361With the 100 pF capacitor shown in Figures 2–4, the high-
pass corner frequency is about 8 MHz.
Figure 2.Basic Connections for Ground Referenced Mode
Figure 3.Basic Connections for Internal Reference Mode
Figure 4.Basic Connections for Supply Referenced Mode
The output voltage is nominally 7.5 times the input rms voltage
(a conversion gain of 7.5 V/V rms). Three different modes of
operation are set by the pins SREF and IREF. In addition to the
ground referenced mode shown in Figure 2, where the output
voltage swings from around near ground to 4.9 V on a 5.0 V
supply, two additional modes allow an offset voltage to be added to
the output. In the internal reference mode, (Figure 3), the
output voltage swing is shifted upward by an internal reference
voltage of 350 mV. In supply referenced mode (Figure 4), an
offset voltage of VS/7.5 is added to the output voltage. Table I
summarizes the connections, output transfer function and mini-
mum output voltage (i.e., zero signal) for each mode.
Output SwingFigure 5 shows the output swing of the AD8361 for a 5 V supply
voltage for each of the three modes. It is clear from Figure 5,
that operating the device in either internal reference mode or
the output headroom decreases. The response for lower supply
voltages is similar (in the supply referenced mode, the offset is
smaller), but the dynamic range will be reduced further, as head-
room decreases. Figure 6 shows the response of the AD8361 to a
CW input for various supply voltages.
INPUT – V rms
OUTPUT
Volts
0.60.70.8Figure 5. Output Swing for Ground, Internal and Supply
Referenced Mode. VPOS = 5 V (micro_SOIC Only)
INPUT – V rms
OUTPUT
Volts
0.60.70.8Figure 6. Output Swing for Supply Voltages of 2.7 V,
3.0 V, 5.0 V and 5.5 V (micro_SOIC Only)
Dynamic RangeBecause the AD8361 is a linear responding device with a nomi-
nal transfer function of 7.5 V/V rms, the dynamic range in dB is
not clear from plots such as Figure 5. As the input level is in-
creased in constant dB steps, the output step size (per dB) will
also increase. Figure 7 shows the relationship between the out-
put step size (i.e., mV/dB) and input voltage for a nominal
transfer function of 7.5 V/V rms.
Table I.Connections and Nominal Transfer Function for
Ground, Internal, and Supply Reference Modes
