LT5581 Datasheet, PDF (1/16 Pages) Linear Technology – 6GHz RMS Power Detector with 40dB Dynamic Range

LT5581
6GHz RMS Power Detector
with 40dB Dynamic Range
FEATURES
n _{Frequency Range: 10MHz to 6GHz}
n _{Accurate Power Measurement of High Crest Factor}
(Up to 12dB) Waveforms
n _{40dB Log Linear Dynamic Range}
n _{Exceptional Accuracy Over Temperature}
n _{Fast Response Time: 1μs Rise, 8μs Fall}
n _{Low Power: 1.4mA at 3.3V}
n _{Log-Linear DC Output vs Input RF Power in dBm}
n _{Small 3mm × 2mm 8-Pin DFN Package}
n _{Single-Ended RF Input}
APPLICATIONS
n _{GSM/EDGE, CMDA, CDMA2000, W-CDMA, LTE,}
WiMAX RF Power Control
n _{Pico-Cells, Femto-Cells RF Power Control}
n _{Wireless Repeaters}
n _{CATV/DVB Transmitters}
n _{MIMO Wireless Access Points}
n _{Portable RMS Power Measurement Instrumentation}
DESCRIPTION
The LT^®5581 is a 10MHz to 6GHz, low power monolithic
precision RMS power detector. The RMS detector uses
a proprietary technique to accurately measure the RF
power from –34dBm to +6dBm (at 2.14GHz) of modulated
signals with a crest factor as high as 12dB. It outputs a DC
voltage in linear scale proportional to an RF input signal
power in dBm. The LT5581 is suitable for precision power
measurement and control for a wide variety of RF standards,
including GSM/EDGE, CDMA, CDMA2000, W-CDMA, TD-
SCDMA, UMTS, LTE and WiMAX, etc. The final DC output
is connected in series with an on-chip 300Ω resistor, which
enables further filtering of the output modulation ripple
with just a single off-chip capacitor.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents,
including 7342431.
TYPICAL APPLICATION
10MHz to 6GHz Infrastructure Power
Amplifier Level Control
POWER
RF_IN
AMP
DIRECTIONAL
COUPLER
RF_OUT
DIGITAL
POWER
CONTROL
0.1μF
ADC
C_FILT
0.01μF
V_CC
2.7V_DC TO 5.25V_DC
0.01μF
1
V_CC
8
C_SQ
1000pF
2
EN
LT5581 ^{RFIN 7}
3
V_OUT
GND ⁶
4 _{GND GND GND} 5
9
C_MATCH
L_MATCH
50Ω
68Ω
5581 TA01a
Linearity Error vs RF Input Power,
2140MHz Modulated Waveforms
3
T_A = 25°C
2
1
0
–1
CW
WCDMA, UL
WCDMA DL 1C
–2
WCDMA DL 4C
LTE DL 1C
LTE DL 4C
–3
–35 –30 –25 –20 –15 –10 –5 0
RF INPUT POWER (dBm)
5 10
5581 TA01b
5581f
1