General Description 

The MAX4003 low-cost, low-power logarithmic amplifier is designed to detect the power levels of RF power amplifiers (PAs) operating from 100MHz to 2500MHz. A typical dynamic range of 45dB makes this logarithmic amplifier useful in a variety of wireless applications including cellular handset PA control, TSSI for wireless terminal devices, and other transmitter power measurements. This logarithmic amplifier provides much wider measurement range and superior accuracy than typical diode-based detectors. Excellent temperature stability is achieved over the full operating range of -40°C to +85°C. The MAX4003 logarithmic amplifier is a voltage-measuring device with a typical signal range of -58dBV to -13dBV. The input signal is internally AC-coupled by an on-chip 5pF capacitor in series with a 2kΩ resistance. This highpass coupling, with a corner at 16MHz, sets the lowest operating frequency and allows the input signal source to be DC grounded. The MAX4003 also features a power-on delay, which holds the detector output (OUT) low for approximately 5µs to ensure glitchless controller output. The MAX4003 is available in an 8-bump chip-scale package (UCSP™), an 8-pin µMAX package, and an 8-pin thin QFN package. The device consumes 5.9mA with a 3.0V supply and only 13µA when the device is in shutdown.

Applications

Cellular Handsets (TDMA, CDMA, GPRS, GSM)

TSSI for Wireless Terminal Devices

Transmitter Power Measurement and Control

RSSI for Fiber Modules