50 Mhz To 4 Ghz 40 Db Logarithmic Power Detector For Cdma And Wcdma - National Semiconductor

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 RS and CS. Figure (b) shows a detector with an additional feedback low pass Filter Resistor RP is optional and will lower the Trans impedance gain (RTRANS). The Filter frequency is set with CP//CTRANS and RP//RTRANS. 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. By National Semiconductor Corporation