 |
Moteur de recherche de fiches techniques de composants électroniques |
|
|
Moteur de recherche de fiches techniques de composants électroniques |
|
TDA9801 Fiches technique(PDF) 6 Page - NXP Semiconductors |
|
||||||||||||||||||||||||||||||
TDA9801 Fiches technique(HTML) 6 Page - NXP Semiconductors |
|
|
6 / 32 page  1999 Aug 26 6 Philips Semiconductors Product specification Single standard VIF-PLL demodulator and FM-PLL detector TDA9801 FUNCTIONAL DESCRIPTION 3-stage IF amplifier The VIF amplifier consists of three AC-coupled differential amplifier stages (see Fig.1). Each differential stage comprises a feedback network controlled by emitter degeneration. AGC detector, IF AGC and tuner AGC The automatic control voltage to maintain the video output signal at a constant level is generated in accordance with the transmission standard. Since the TDA9801(T) is suitable for negative modulation only the peak sync pulse level is detected. The AGC detector charges and discharges capacitor CAGC to set the IF amplifier and tuner gain. The voltage on capacitor CAGC is transferred to an internal IF control signal, and is fed to the tuner AGC to generate the tuner AGC output current on pin TAGC (open-collector output). The tuner AGC takeover point level is set at pin TOP. This allows the tuner to be matched to the SAW filter in order to achieve the optimum IF input level. Frequency detector and phase detector The VIF amplifier output signal is fed into a frequency detector and into a phase detector. During acquisition the frequency detector produces a DC current proportional to the frequency difference between the input and the VCO signal. After frequency lock-in the phase detector produces a DC current proportional to the phase difference between the VCO and the input signal. The DC current of either frequency detector or phase detector is converted into a DC voltage via the loop filter which controls the VCO frequency. Video demodulator The true synchronous video demodulator is realized by a linear multiplier which is designed for low distortion and wide bandwidth. The vision IF input signal is multiplied with the ‘in phase’ component of the VCO output. The demodulator output signal is fed via an integrated low-pass filter (fg = 12 MHz) for suppression of the carrier harmonics to the video amplifier. VCO, AFC detector and travelling wave divider The VCO operates with a symmetrically connected reference LC circuit, operating at the double vision carrier frequency. Frequency control is performed by an internal variable capacitor diode. The voltage to set the VCO frequency to the actual double vision carrier frequency is also amplified and converted for the AFC output current. The VCO signal is divided-by-2 with a Travelling Wave Divider (TWD) which generates two differential output signals with a 90 degree phase difference independent of the frequency. Video amplifier The composite video amplifier is a wide bandwidth operational amplifier with internal feedback. A nominal positive video signal of 1 V (p-p) is present at pin VSO. Buffer amplifier and noise clipper The input impedance of the 7 dB wideband CVBS buffer amplifier (with internal feedback) is suitable for ceramic sound trap filters. Pin CVBS provides a positive video signal of 2 V (p-p). Noise clipping is provided internally. Sound demodulation LIMITER AMPLIFIER The FM sound intercarrier signal is fed to pin SI and through a limiter amplifier before it is demodulated. The result is high sensitivity and AM suppression. The limiter amplifier consists of 7 stages which are internally AC-coupled in order to minimizing the DC offset. FM-PLL DETECTOR The FM-PLL demodulator consists of an RC oscillator, loop filter and phase detector. The oscillator frequency is locked on the FM intercarrier signal from the limiter amplifier. As a result of this locking, the RC oscillator is frequency modulated. The modulating voltage (AF signal) is used to control the oscillator frequency. By this, the FM-PLL operates as an FM demodulator. AF AMPLIFIER The audio frequency amplifier with internal feedback is designed for high gain and high common-mode rejection. The low-level AF signal output from the FM-PLL demodulator is amplified and buffered in a low-ohmic audio output stage. An external decoupling capacitor CDAF removes the DC voltage from the audio amplifier input. By using the sound mute switch (pin MUTE) the AF amplifier is set in the mute state. |
Numéro de pièce similaire - TDA9801 |
|
Description similaire - TDA9801 |
|
|
Lien URL |
| Politique de confidentialité |
| ALLDATASHEET.FR |
| ALLDATASHEET vous a-t-il été utile ? [ DONATE ] |
À propos de Alldatasheet | Publicité | Contactez-nous | Politique de confidentialité | Echange de liens | Fabricants All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
French ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
