MLX71122_16 datasheet(32/59 Pages) MELEXIS

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MLX71122

300 to 930MHz FSK/FM/ASK Receiver

Datasheet

REVISION 014 – AUGUST, 2016

Page 32 of 59

390 10 71122 01

3.3.7. Automatic Gain Control (AGC)

The Automatic Gain Control (AGC) can be activated in SPI mode with AGCEN (see 4.1.4). By default, it is

turned off. It uses the RSSIH and RSSIL signals of the IF amplifier to determine whether the gain has to be

increased or decreased. The gain will be decreased beginning with the gain of the last stage. The gain

increase works vice versa. The AGC circuit controls the gain of the LNA, and of mixer 1 and mixer 2. To

avoid rapid gain switching, caused by short signal strength fluctuations or during ASK reception, the gain

control operates with a time delay that can be programmed via AGCDEL (see 4.1.4). The time delay also

depends on the PFD frequency of the IF filter auto-tuning circuit. There is no delay by default. AGCMODE

(see 4.1.5), a second setting, determines whether the delay is applied for gain increase and decrease or

only for gain increase. By default, a delay for increase and decrease is used.

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