TEF6730A NXP Semiconductors, TEF6730A Datasheet - Page 9

• Manufacturer Part Number: TEF6730A
• Description: Tef6730a Front-end For Digital-if Car Radio
• Manufacturer: NXP Semiconductors

NXP Semiconductors
8. I
TEF6730A_1
Product data sheet
Fig 3. Write mode
2
C-bus protocol
S
SLAVE ADDRESS W
7.4 AM LNA
7.5 AM RF AGC
7.6 AM mixer
7.7 VCO and dividers
7.8 Tuning PLL
7.9 AM/FM IF AGC amplifier
The AM low noise amplifier is fully integrated.
The AM RF AGC is partially integrated. Detection is at the output of the AM LNA and at
the input of the AM/FM IF AGC amplifier, both with programmable thresholds. First the
integrated AGC reduces the gain of the LNA. After the LNA AGC, the PIN diode AGC
takes over by sinking a current via an external PIN diode.
In FM mode, the AM AGC can be set to a fixed attenuation.
The large dynamic range AM mixer converts AM RF (144 kHz to 26.1 MHz) to an IF
frequency of 10.7 MHz.
The varactor tuned LC oscillator together with the dividers provides the LO signal for both
AM and FM front-end mixers. The VCO has an operating frequency of approximately
160 MHz to 256 MHz. In FM mode the LO frequency is divided by 2 or 3. These dividers
generate in-phase and quadrature-phase output signals used in the FM front-end mixer
for image rejection. In weather band mode the LO signal is directly phase shifted to
generate the in-phase and quadrature-phase signals. In AM mode the LO frequency is
divided by 6, 8, 10, 16 or 20 depending on the selected AM band.
The tuning PLL locks the VCO frequency divided by the programmable divider ratio to the
reference frequency. Due to the combination of different charge pump signals in the
PLL loop filter, the loop parameters are adapted dynamically. Tuning to different
RF frequencies is done by changing the programmable divider ratio. The tuning step size
is selected with the reference frequency divider setting.
The combined AM/FM IF AGC amplifier delivers a suitable IF signal for the ADC in the
IF DSP. The maximum gain of the IF AGC amplifier can be selected via the I
gain of this amplifier is automatically adapted via interfacing signals from the IF DSP. The
IF AGC amplifier has three signal inputs, two for FM and one for AM. This allows the
application of multiple external filters, e.g. with different bandwidths.
ACK-s
Rev. 01 — 21 February 2007
MSA
ACK-s
(n bytes
Front-end for digital-IF car radio
DATA
data transferred
acknowledge)
TEF6730A
© NXP B.V. 2007. All rights reserved.
ACK-s
001aad051
2
C-bus. The
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