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PDF TDA9803 Data sheet ( Hoja de datos )
| Número de pieza | TDA9803 | |
| Descripción | Multistandard VIF-PLL demodulator | |
| Fabricantes | NXP Semiconductors | |
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INTEGRATED CIRCUITS
DATA SHEET
TDA9803
Multistandard VIF-PLL
demodulator
Preliminary specification
File under Integrated Circuits, IC02
November 1992
Datasheet pdf - http://www.DataSheet4U.net/
1 page  
www.DataSheet.co.kr
Philips Semiconductors
Multistandard VIF-PLL demodulator
Preliminary specification
TDA9803
FUNCTIONAL DESCRIPTION
Vision IF input
The vision IF amplifier consists of three AC-coupled
differential amplifier stages; each stage comprises a
controlled feedback network by means of emitter
degeneration.
IF and tuner AGC
The automatic control voltage to maintain the video output
signal at a constant level is generated according to the
transmission standard. For negative modulation the
peak-sync level is detected, for positive modulation the
peak white level is detected. The AGC detector charges
and discharges the capacitor on pin 19 to set the IF gain
and the tuner gain. The standard is switched by the voltage
on pin 8. To reduce the response time for positive
modulation (which needs a very long time constant) a
black level detector (CBL) increases the AGC capacitor
discharge current for low-level video signals.
The AGC capacitor voltage is transferred to an internal IF
control signal, and is fed to the tuner AGC to generate the
tuner AGC output current on pin 12 (open-collector
output). The tuner AGC voltage take over point is adjusted
on pin 3. This allows the tuner and the IF SAW filter to be
matched to achieve the optimum IF input level.
Frequency detector, phase detector and video
demodulator
The IF amplifier output signal is fed to a frequency detector
and to a phase detector. The frequency detector is
operational before lock-in. A DC current is generated
which is proportional to the frequency difference between
the input frequency and the VCO frequency. After lock-in,
the frequency detector and the phase detector generate a
DC current proportional to the phase difference between
VCO and input signals. The control signal for the VCO is
provided by the phase detector. The video demodulator is
a linear multiplier, designed for low distortion and wide
bandwidth. The vision IF input signal is multiplied by the
in-phase component of the VCO output. The demodulated
output signal is fed via an integrated low-pass filter
(fg = 12 MHz) to the video amplifier for suppression of the
carrier harmonics. The polarity of the video signal is
switched in the demodulator stage according to the TV
standard.
VCO and travelling wave divider
The VCO operates with a symmetrically-connected
reference LC-circuit, operating at double vision carrier
frequency. Frequency control is performed by an internal
varicap diode. The voltage to set the VCO frequency to the
actual frequency of double vision carrier frequency, is also
amplified and converted for the AFC output current.
The VCO signal is divided-by-two in a travelling wave
divider, which generates two differential output signals
with 90 degree phase difference independent of
frequency.
Video amplifier, buffer and noise clipping
The video amplifier is a wide bandwidth operational
amplifier with internal feedback. Dependent on
transmission standard, a level shifter provides the same
sync level for positive as for negative modulation. A
nominal positive modulated video signal of 1 V (p-p) is
present on the composite video output (pin 13).
The input impedance of the 7 dB wideband buffer amplifier
(with internal feedback) is suitable for ceramic sound trap
filters.
The CVBS output (pin 7) provides a positive video signal
of 2 V (p-p). Noise clipping is provided internally.
November 1992
5
Datasheet pdf - http://www.DataSheet4U.net/
5 Page 
www.DataSheet.co.kr
Philips Semiconductors
Multistandard VIF-PLL demodulator
Preliminary specification
TDA9803
9. The intercarrier output signal is superimposed to the video signal at pin 13 and can be calculated by the following
formula:
20
log
V-----1--31----i-nV--t-e---r-(c-p--.--(---pp---)---p----)--
=
V-V----ii-SP---CC-- + 6.9 dB ±2 dB
with: V-V----ii-SP---CC-- dB = sound to picture carrier ratio at IF input (pins 1 and 2 ) in dB
and
±2 dB = tolerance of intercarrier output amplitude Vo FM.
10. Measurements taken with SAW filter G1956; modulation: VSB, fvideo > 0.5 MHz, loop bandwidth BL = 60 kHz.
11. The 7 dB buffer gain accounts for 1 dB loss in the sound trap. Buffer output signal is typical 2 V (p-p). If no sound
trap is applied a 330 Ω resistor must be connected from output to input (from pin 13 to pin 14).
12. The leakage current of the AGC capacitor has to be < 1 µA in B/G mode (< 30 nA in L mode) to avoid larger tilt.
13. S/N is the ratio of black-to-white amplitude to the black level noise voltage (RMS value, pin 7). B = 5 MHz weighted
in accordance with CCIR-567 at a source impedance of 50 Ω.
14. α1.1 = 20 log (Vo at 4.4 MHz / Vo at 1.1 MHz) + 3.6 dB; α1.1 value at 1.1 MHz related to black/white signal
α3.3 = 20 log (Vo at 4.4 MHz / Vo at 3.3 MHz); α3.3 value at 3.3 MHz related to colour carrier.
15. To match the AFC output signal to different tuning systems a current source output is provided (Fig.8).
16. Depending on the ratio ∆C/Co of the LC resonance circuit of VCO
(Qo > 50; Co = Cint + Cext; Cext = 8.2 pF; Cint ≈ 8.5 pF).
November 1992
11
Datasheet pdf - http://www.DataSheet4U.net/
11 Page | ||
| Páginas | Total 21 Páginas | |
| PDF Descargar | [ Datasheet TDA9803.PDF ] | |
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