TDA5230 Datasheet, PDF(66/186 Page) Infineon Technologies AG – Universal Low Power ASK/FSK Single Conversion Multi-Channel Image-Reject Receiver

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TDA5230 Datasheet, PDF (66/186 Pages) Infineon Technologies AG – Universal Low Power ASK/FSK Single Conversion Multi-Channel Image-Reject Receiver

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TDA523x

2.4.7

RFIN+

RFIN-

RF Path

RF-Mixer

LNA

Poly-

phase

Filter

LO-Signals

Functional Description

SUM-

Amplifier

Digitally

Adjustable

IF-Attenuator

0 .. -12 dB

IF-

Driver-

Amp.

IF-OUT

Figure 29 RF Path

RFIN+ and RFIN- are inputs to the on chip LNA.

RF is usually connected to RFIN+, and RFIN- is grounded. If a filter with differential

outputs is used, such as a SAW filter, the differential inputs may be used accordingly.

The LNA directly drives the two in quadrature driven RF Mixers. The outputs of the two

mixers are fed to a polyphase filter that provides active suppression of input signals at

the image frequency of the desired input signal. The center frequency of the polyphase

filter and the following blocks at the IF frequency is 10.7 MHz.

The RF mixer and poly phase filter are capable to support a Hi-Side and a Lo-Side LO

Injection mode. Selection of the LO Injection mode is controlled via the SFR-control bit

SSBSEL.

The polyphase filter is followed by a digitally adjustable IF attenuator. This allows the

production spread of the on chip signal strip, of external LNA and matching circuitry and

RF SAW and ceramic IF filters to be trimmed out. The attenuator offers a programmable

attenuation range of 12 dB, programmable in 16 Steps and is controlled via the SFR

control bits IFATT. An IF driver amplifier with a characteristic output impedance of 330 â¦

allows simple interfacing to external ceramic IF filters.

For adjustment of the RSSI offset the complete RF path can be switched off via the SFR

control bit RFOFF.

Data Sheet

Version 4.0, 2007-06-01

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