LTC5587_15 Datasheet, PDF (1/20 Pages) Linear Technology – 6 GHz RMS Power Detector with Digital Output

LTC5587
6 GHz RMS Power Detector
with Digital Output
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 _{Single-Ended RF Input}
n _{0.014dB/Bit (12-Bit) ADC Resolution (VREF = 1.8V)}
n _{ADC Sample Rate Up to 500ksps}
n _{SPI/MICROWIRE Serial I/O}
n _{Compatible with 1V to 3.6V Digital Logic}
n _{Fast Response Time: 1μs Rise, 8μs Fall}
n _{Low Power: 3mA at 3.3V and 500ksps}
n _{Small 3mm × 3mm 12-pin DFN Package}
APPLICATIONS
n _{LTE, WiMAX, W-CDMA, TD-SCDMA, CDMA,}
CDMA2000, EDGE, GSM
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}
n _{Antenna Monitor}
DESCRIPTION
The LTC^®5587 is a 10MHz to 6GHz, low power monolithic
precision RMS power detector with an integrated 12-bit
serial analog-to-digital converter (ADC). The RMS detec-
tor uses a proprietary technique to accurately measure the
RF power of modulated signals with crest-factor as high
as 12dB. For an input frequency of 2.14GHz the detection
range is from –34dBm to 6dBm. The serial digital output
of the detector is a 12-bit word value that is directly pro-
portional to the RF signal power measured in dBm. The
LTC5587 is suitable for precision power measurement
for a wide variety of RF standards, including LTE, WiMAX,
W-CDMA, TD-SCDMA, CDMA, CDMA2000, EDGE, GSM,
etc. The DC output of the detector is connected in series
with an on-chip 300Ω resistor to the analog output pin
(V_OUT). This enables further filtering of the output modu-
lation ripple using an off-chip capacitor before analog-to-
digital conversion. The ADC features include no data latency,
no missing codes, and a sampling rate of up to 500ksps. A
dedicated external reference pin (V_REF) can be tied to V_DD
or other suitable low-impedance voltage reference to set the
ADC full-scale input voltage range. The ADC also features
an automatic power down after each conversion making
the LTC5587 ideal for low-power applications.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
BLOCK DIAGRAM
RF
7
13
EXPOSED
PAD
150kHz LPF
RMS
DETECTOR
OUTPUT
BUFFER
300Ω
4
V_OUT
S/H
BIAS
6 ^CSQ
EN
9
8 ^VCC
GND
5
11
V_DD
3
OV_DD
12-BIT ADC
THREE-STATE
SERIAL OUTPUT
PORT
SDO
1
10 ^VREF
TIMING
LOGIC
SCK
2
CONV
12
5587 BD
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
5587 G12
5587f
1