TDA5230 Datasheet, PDF (70/186 Pages) Infineon Technologies AG – Universal Low Power ASK/FSK Single Conversion Multi-Channel Image-Reject Receiver

TDA523x
Functional Description
If bandwidth switching is required, the first IF Filter is wideband, and is used if the IF MUX
is switched to IFBUF-IN. The second IF Filter is narrowband, if the IF MUX is switched
to LIM-IN+, the narrow characteristic of this filter overrides the wide first IF Filter.
One-Filter application
Two-Filter application
Optional One-Filter
application
(2nd IF-filter disabled)
IF-OUT IFBUF-IN
IFBUF-OUT LIM-IN+
Figure 31 External IF Filter Configurations
Dual: AIF0 and BIF0: Conf.A IF Buffer Amplifier Enable
ADDR: 0x3F and 0x60
Reset Value: 0x00
Bit R/W Description
1 W IFBUF: Enable IF Buffer amplifier
0: Buffer disabled, used for single IF filter
1: Buffer enabled, used for dual IF filter configuration
0 W IFMUX: select IF-limiter input
0: use pin LIM-IN+ as input
1: use pin IFBUF-IN as input
2.4.8.2 Limiter, RSSI
The limiter is an AC coupled multistage amplifier with a wide bandpass characteristic
centered around 10.7 MHz. The limited IF signal is fed to the digital FSK Demodulator.
The limiter circuit also acts as a Receive Signal Strength Indicator (RSSI) generator that
produces a voltage signal proportional to the logarithm of the input signal level.
Data Sheet
66
Version 4.0, 2007-06-01