1.

General description

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

functions down to 2.7 V. The RF section is similar to the famous NE605. The data output

provides a minimum bandwidth of 1 MHz to demodulate wideband data. The RSSI output

is amplified and has access to the feedback pin. This enables the designer to level adjust

the outputs or add filtering.

The post-detection amplifier 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

(POWER_DOWN_CTRL) is HIGH. Power down logic levels are CMOS and TTL

compatible with high input impedance.

2.

Features and benefits

injected)

a dynamic range in excess of 80 dB

SA639

Low voltage mixer FM IF system with filter amplifier and

data switch

Rev. 4 — 10 July 2014

Product data sheet