TDA10045 Philips Semiconductors, TDA10045 Datasheet - Page 13

• Manufacturer Part Number: TDA10045
• Description: DVB-T channel receiver
• Manufacturer: Philips Semiconductors

Philips Semiconductors
Tuner
IF interface
2001 Nov 08
A RF tracking filter tracks the RF wanted frequency and
suppresses the image
A first local wideband AGC is usually done at RF level,
the AGC level information could be provided externally
and the chip offers facilities to measure this level by the
optional ADC (this measurement is automatically made
by the DSP, the host has just to read the result)
A mixer oscillator and a PLL downconverts the RF signal
to intermediate frequency IF1 (36.125 MHz typ.)
SAW filters eliminate the power of the adjacent channels
around IF1.
It is either an analog IF amplifier when IF1 is sampled
(direct IF: digital downconversion concept) or an analog
IF amplifier followed by a downconversion from IF1 to
IF2 at a few MHz (e.g. 4.57 MHz)
When this second solution is used, the ADC sampling
clock could be used (after low-pass filtering) as a
reference clock for downconversion (twice the ADC
sampling clock could also be provided)
The IF amplifier is controlled by the digital AGC of the
chip. A simple RC circuit filters the single bit
(
The sampling clock could also be used to control an
external ADC, the inputs to the chip will then be digital
(FI[9:0]).
DVB-T channel receiver
modulated) AGC control (VAGC)
13
TDA10045H
The chip is controlled by an I
external low-cost crystal oscillator
The software of the embedded DSP can be downloaded
from the main I
connected to an external slave I
An internal bidirectional switch enables the tuner to be
programmed through the chip and then switch-off the
link in order to avoid phase noise distortions due to
I
2
C-bus traffic.
2
C-bus or from a dedicated I
2
C-bus and driven by an
2
C-bus EEPROM
TDA10045H
Product specification
2
C-bus