LT5502 Datasheet | Linear Technology

Features s Single 1.8V to 5.25V Supply s IF Frequency Range: 70MHz to 400MHz s 84d B Limiting IF Gain s 90d B Linear RSSI Range s 7.7MHz Lowpass Output Filter s Baseband I/Q Amplitude Imbalance: <0.7d B s 4d B Noise Figure s Low Supply Current: 25m A s Outputs Biased Up While in Standby s Shutdown Current: 1µA s 24-Lead Narrow SSOP Package U APPLICATIO S s IEEE802.11 s High Speed Wireless LAN s Wireless Local Loop TYPICAL APPLICATIO 400MHz Quadrature IF Demodulator with RSSI DESCRIPTIO The LT®5502 is a 70MHz to 400MHz monolithic integrated quadrature IF demodulator. It consists of an IF limiter, quadrature down mixers, integrated lowpass filters, and divide-by-two LO buffers. The demodulator provides all building blocks for demodulation of I and Q baseband signals with a single supply voltage of 1.8V to 5.25V. The IF limiter has 84d B small-signal gain, and a built-in receive signal strength indicator (RSSI) with over 90d B linear range. The input referred noise-spectral-density is 1.45n V/√Hz, which is equivalent to a 4d B noise figure when the input is terminated with a 50Ω source. The integrated lowpass output filters act as antialiasing and pulse-shaping filters for demodulated I/Q-baseband signals. The 3d B cutoff frequency of the filters is about 7.7MHz. The VCO frequency is required to be twice the desired operating frequency to provide quadrature local oscillator (LO) signals to the mixers. The standby mode provides fast transient response to the receive mode with reduced supply current when the I/Q outputs are AC-coupled to a baseband chip. , LTC and LT are registered trademarks of Linear Technology Corporation. IF INPUT 2XLO INPUT C2 1µF C3 22n F IF+ R1 240Ω - 2XLO+ 2XLO- ENABLE EN 2V C1 1n F 90° ÷2 0° LT5502 GND I/Q Output Swing, RSSI Output vs IF Input Power DIFFERENTIAL OUTPUT SWING (m VP-P) RSSI OUTPUT (V) IOUT+ IOUT- QOUT+ QOUT- RSSI BASEBAND DIFFERENTIAL I/Q OUTPUTS C4 1.8p F 5502...