tda9882ts-v1 NXP Semiconductors, tda9882ts-v1 Datasheet - Page 7

• Manufacturer Part Number: tda9882ts-v1
• Description: Tda9882 Alignment-free Multistandard Vision And Qss Fm Sound If-pll Demodulator
• Manufacturer: NXP Semiconductors

Philips Semiconductors
8. Functional description
9397 750 13507
Product data sheet
8.1 VIF amplifier
8.2 Tuner AGC and VIF AGC
8.3 VIF AGC detector
A simplified block diagram of the device is illustrated in
following functional blocks:
The VIF amplifier consists of three AC-coupled differential stages. Gain control is
performed by emitter degeneration. The total gain control range is typical 66 dB. The
differential input impedance is typical 2 k in parallel with 3 pF.
This block adapts the voltage, generated at the VIF AGC detector, to the internal signal
processing at the VIF amplifier and performs the tuner AGC control current generation.
The onset of the tuner AGC control current generation can be set by a potentiometer at
pin TOP.
Gain control is performed using sync level detection (negative modulation) or peak white
detection (positive modulation).
For negative modulation, the sync level voltage is stored in an integrated capacitor by
means of a fast peak detector. This voltage is compared with a reference voltage (nominal
sync level) by a comparator which charges or discharges the integrated AGC capacitor to
generate the VIF gain. The time constants for decreasing or increasing the gain are nearly
equal and the total AGC reaction time is fast, to cope with ‘aeroplane fluttering’.
1. VIF amplifier
2. Tuner AGC and VIF AGC
3. VIF AGC detector
4. Frequency Phase-Locked Loop (FPLL) detector
5. VCO and divider
6. AFC and digital acquisition help circuit
7. Video demodulator and amplifier
8. Sound carrier trap
9. SIF amplifier
10.SIF AGC detector
11.Single reference QSS mixer
12.AM demodulator
13.FM demodulator and acquisition help circuit
14.Audio amplifier and mute time constant
15.Internal voltage stabilizer
16.Logic.
Rev. 01 — 16 November 2004
Multistandard vision and QSS FM sound IF PLL demodulator
Figure
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
1. The device contains the
TDA9882
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