TDA6190 Datasheet, PDF (13/30 Pages) Infineon Technologies AG – DVB-IF Mixer

2.5
Functional Block Description
TDA 6190
Version 1.4
Functional Description
2.5.1 Power Supply, Reference Voltage
The 3.6 V low noise reference voltage Vref is used as a reference for the adjustment of
the delayed tuner AGC. The reference voltage has a low temperature coefficient and
high line regulation.
2.5.2 DVB-IF Input Amplifier, AGC
The filtered IF signal is fed to the balanced input pins IF1 / IF2 of the gain controlled
amplifier, where it is amplified and then down converted to the output frequency signals.
The control voltage for the gain-controlled amplifier at pin IFAGC is applied from external
source.
If the IFAGC control voltage level exceeds an adjustable value (TAGCthr), a sink current
at TunAGC is generated which controls the tuner gain.
2.5.3 Oscillator
The symmetrical 4 pin voltage controlled oscillator feeds the mixer to generate the down
converted DVB-IF signals.The frequency of the VCO is below or above the input
frequency of the AGC amplifier. The control voltage for the external varactor diode is
derived from the DVB processor.
2.5.4 Mixer and Output Buffers
The mixer converts the filtered and amplified IF signal down to the low IF frequency. This
frequency is fed to a balanced output pair OUT1 and OUT2.
Specification
13
2004-05-17