SA58640 Datasheet, PDF (4/16 Pages) NXP Semiconductors – Low-voltage mixer FM IF system

Philips Semiconductors
SA58640
Low-voltage mixer FM IF system
fixed or variable resistor or an L pad for simultaneous loss and impedance matching can
be added between the first IF output (pin 16) and the interstage network. The overall gain
will then be 90 dB with 2 MHz bandwidth.
The signal from the second limiting amplifier goes to a Gilbert cell quadrature detector.
One port of the Gilbert cell is internally driven by the IF. The other output of the IF is
AC-coupled to a tuned quadrature network. This signal, which now has a 90q phase
relationship to the internal signal, drives the other port of the multiplier cell.
The demodulated output of the quadrature drives an internal opamp. This opamp can be
configured as a unity gain buffer, or for simultaneous gain, filtering, and 2nd-order
temperature compensation if needed. It can drive an AC load as low as 10 k: with a
rail-to-rail output.
A log signal strength indicator completes the circuitry. The output range is greater than
70 dB and is temperature compensated. This signal drives an internal opamp. The opamp
is capable of rail-to-rail output. It can be used for gain, filtering, or 2nd-order temperature
compensation of the RSSI, if needed.
9397 750 14161
Objective data sheet
Rev. 01 — 1 November 2004
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
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