LMH2100 Datasheet, PDF (1/32 Pages) National Semiconductor (TI) – 50 MHz to 4 GHz 40 dB Logarithmic Power Detector for CDMA and WCDMA

November 28, 2007
LMH2100
50 MHz to 4 GHz 40 dB Logarithmic Power Detector for
CDMA and WCDMA
General Description
The LMH2100 is a 40 dB RF power detector intended for use
in CDMA and WCDMA applications. The device has an RF
frequency range from 50 MHz to 4 GHz. It provides an accu-
rate temperature and supply compensated output voltage that
relates linearly to the RF input power in dBm. The circuit op-
erates with a single supply from 2.7V to 3.3V.
The LMH2100 has an RF power detection range from −45
dBm to −5 dBm and is ideally suited for direct use in combi-
nation with a 30 dB directional coupler. Additional low-pass
filtering of the output signal can be realized by means of an
external resistor and capacitor. Figure (a) shows a detector
with an additional output low pass filter. The filter frequency
is set with R_S and C_S.
Figure (b) shows a detector with an additional feedback low
pass filter. Resistor R_P is optional and will lower the Trans
impedance gain (R_TRANS). The filter frequency is set with
C_P//C_TRANS and R_P//R_TRANS.
The device is active for Enable = High, otherwise it is in a low
power consumption shutdown mode. To save power and pre-
vent discharge of an external filter capacitance, the output
(OUT) is high-impedance during shutdown.
The LMH2100 power detector is offered in the small 0.4 mm
pitch micro SMD package.
Features
■ ^{40 dB linear in dB power detection range}
■ ^{Output voltage range 0.3 to 2V}
■ ^Shutdown
■ ^{Multi-band operation from 50 MHz to 4 GHz}
■ ^{0.5 dB accurate temperature compensation}
■ ^{External configurable output filter bandwidth}
■ ^{0.4 mm-pitch micro SMD package}
Applications
■ ^{UMTS/CDMA/WCDMA RF power control}
■ ^{GSM/GPRS RF power control}
■ ^{PA modules}
■ ^{IEEE 802.11b, g (WLAN)}
Typical Application
30014071
(a) LMH2100 with Output RC Low Pass Filter
30014004
(b) LMH2100 with Feedback (R)C Low Pass Filter
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