SA639

• V_CC = 2.7 to 5.5V
• Low power consumption: 8.6mA typ at 3V
• Wideband data output (1MHz min.)
• Fast RSSI rise and fall times
• Mixer input to >500MHz
• Mixer conversion power gain of 9.2dB and noise figure of 11dB at 110MHz
• XTAL oscillator effective to 150MHz (L.C. oscillator to 1GHz local oscillator can be injected)
• 92dB of IF Amp/Limiter power gain
• 25MHz limiter small signal bandwidth
• Temperature compensated logarithmic Received Signal Strength Indicator (RSSI) with a dynamic range in excess of 80dB
• RSSI output internal op amp
• Post detection amplifier for filtering
• Programmable data switch
• Excellent sensitivity: 2.24V into 50W matching network for 10dB SNR (Signal to Noise Ratio) with RF at 110MHz and IF at 9.8MHz
• ESD hardened
• Power down mode

The SA639 is a low-voltage high performance monolithic FM IF system with high-speed RSSI incorporating a mixer/oscillator, two wideband limiting intermediate frequency amplifiers, quadrature detector, logarithmic received signal strength indicator (RSSI), fast RSSI op amps, voltage regulator, wideband data output, post detection filter amplifier and data switch. The SA639 is available in 24-lead TSSOP (Thin shrink small outline package).

The SA639 was designed for high bandwidth portable communication applications and will function down to 2.7V. The RF section is similar to the famous NE605. The data output provides a minimum bandwidth of 1MHz to demodulate wideband data. The RSSI output is amplified and has access to the feedback pin. SA639 enables the designer to level adjust the outputs or add filtering.

The post-detection amplifier SA639 may be used to realize a low pass filter function. A programmable data switch routes a portion of the data signal to an external integration circuit that generates a data comparator reference voltage.

SA639 incorporates a power down mode which powers down the device when Pin 8 is high. Power down logic levels are CMOS and TTL compatible with high input impedance.