TUA4300G Infineon Technologies Corporation, TUA4300G Datasheet - Page 4

• Manufacturer Part Number: TUA4300G
• Description: One Chip Car Radio, AM/FM Receiver
• Manufacturer: Infineon Technologies Corporation

FS: 04/93
1. AM/FM-Receiver
The AM/FM-receiver part includes a 2-pin varactor tuned oscillator. In the FM mode the direct oscillator frequency is
fed into the double balanced FM mixer, in the AM mode the divided by 8 or 10 oscillator frequency is fed into the AM
mixer.
The two separate symmetrical input stages of the IC, one optimized for FM-, the other for AM- mode allow symmetrical
and unsymmetrical prestage configuration.
The AM and FM input frequencies are converted to a fix 1st IF in the 10.7 MHz range. The IF is post amplified in
separate IF amplifiers, one optimized for FM, the other for AM. Using of a CER filter or crystal filter is possible.
The TUA 4300 G has been designed to work with a PLL in the 100MHz range in both modes or in the AM- mode with
the divided frequency.
Depending on the input signal strength, the integrated AGC stage for prestage control drives PIN-Diodes as well as
MOSFETs.
2. FM-MODE
A. FM-IF Demodulator
The FM-IF amplifier includes a 7 stage capacitive coupled limiter amplifier with coincidence demodulator and AF
output. The AF output signal can be continuously attenuated to decrease the noise.
There is a field strength output (with min. 76 dB dynamic range, typ. 1 dB nonlinearity and typ. 3 dB temperature
drift) and a fixed muting (with full muting typ 80 dB).
A multipath detector with analog output is available. Its input signal is fed from the high pass filter of the stereo-
decoder/noiseblanker and a second 80 kHz 1-pole high pass filter.
3. Stereodecoder
Power supply, reference current:
A temperature-stable, low noise reference voltage generator is used for better ripple rejection and to generate a
reference current. This current is used as a time base for the deemphasis, the gate time of the pulse former, and the
pilot cancellation, avoiding temperature and tolerance effects .
MPX input, MPX filter:
Voltage Controlled Oscillator, Phase Detector:
The 456 kHz oscillator and the frequency dividers are used as walsh function generators (suppression of 3
order harmonics) for:
The phase detector locks the on chip 19 kHz signal to the pilot tone in the MPX signal at 90 deg phase.
Pilot Detector, Pilot Indicator, Pilot Cancellation:
The voltage at the pilot detector output is proportional to the pilot tone input level. If that level is high enough, the pilot
indicator output is activated and the pilot cancellation turned on: a 19 kHz signal proportional to the voltage at the pilot
detector output is added to the MPX signal with inverse polarity, cancelling the 19 kHz pilot tone.
Interference Detector , Noise Detector, Pulse Former:
The signal from the interference input (MPX or field strength signal) passes a 4-pole high-pass filter to the noise
blanking circuitry. The average noise level is stored in an external capacitor. The interference detector compares the
actual noise level with that stored in the capacitor and triggers the pulse former if there is a significant difference. The
pulse former generates a gate pulse for the HCC block. During that pulse time the outputs of the deemphasis circuit
are switched to hold mode.
A 4-pole low-pass filter determines the bandwidth of the MPX signal.
SIEMENS AG
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HL DOK
38 kHz for the stereo decoder
19 kHz inphase for phase detector and pilot cancellation
19 kHz quadrature for the phase detector.
V66047-S695-G100-G1
Circuit Description
TUA 4300 G
IC-SPECIFICATION
12.11.96
rd
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