參數(shù)資料
型號(hào)： TDA9884HN
廠商： NXP SEMICONDUCTORS
元件分類： 接收器
英文描述： AM/FM, AUDIO/VIDEO DEMODULATOR, PQCC32
封裝： 5 X 5 MM, 0.85 MM HEIGHT, PLASTIC, MO-220, HVQFN-32
文件頁(yè)數(shù)： 4/58頁(yè)
文件大小： 290K
代理商： TDA9884HN
TDA9884_2
Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Product data sheet
Rev. 02 — 12 May 2006
12 of 58
Philips Semiconductors
TDA9884
I2C-bus controlled multistandard alignment-free IF-PLL
7.13 FM demodulator and acquisition help
The narrow-band FM-PLL detector consists of:
Gain controlled FM amplier and AGC detector
Narrow-band PLL
The intercarrier signal from the intercarrier mixer is fed to the input of an AC-coupled gain
controlled amplier with two stages. The gain controlled output signal is fed to the phase
detector of the narrow-band FM-PLL (FM demodulator). For good selectivity and
robustness against disturbance caused by the video signal, a high linearity of the gain
controlled FM amplier and of the phase detector as well as a constant signal level are
required. The gain control is done by means of an ‘in phase’ demodulator for the
FM carrier (from the output of the FM amplier). The demodulation output is fed into a
comparator for charging or discharging the integrated AGC capacitor. This leads to a
mean value AGC loop to control the gain of the FM amplier.
The FM demodulator is realized as a narrow-band PLL with an external loop lter, which
provides the necessary selectivity (bandwidth approximately 100 kHz). To achieve good
selectivity, a linear phase detector and a constant input level are required. The gain
controlled intercarrier signal from the FM amplier is fed to the phase detector. The phase
detector controls via the loop lter the integrated low radiation relaxation oscillator. The
designed frequency range is from 4 MHz to 7 MHz.
The VCO within the FM-PLL is phase-locked to the incoming 2nd SIF signal, which is
frequency modulated. As well as this, the VCO control voltage is superimposed by the
AF voltage. Therefore, the VCO tracks with the FM of the 2nd SIF signal. So, the
AF voltage is present at the loop lter and is typically 5 mV (RMS) for 27 kHz
FM deviation. This AF signal is fed via a buffer to the audio amplier.
The correct locking of the PLL is supported by the digital acquisition help circuit
7.14 Audio amplier and mute time constant
The audio amplier consists of two parts:
AF preamplier
AF output amplier
The AF preamplier used for FM sound is an operational amplier with internal feedback,
high gain and high common mode rejection. The AF voltage from the PLL demodulator is
5 mV (RMS) for a frequency deviation of 27 kHz and is amplied by 30 dB. By the use of a
DC operating point control circuit (with external capacitor CAF), the AF preamplier is
decoupled from the PLL DC voltage. The low-pass characteristic of the amplier reduces
the harmonics of the sound intercarrier signal at the AF output terminal.
For FM sound a switchable de-emphasis network (with external capacitor) is implemented
between the preamplier and the output amplier.
The AF output amplier provides the required AF output level by a rail-to-rail output stage.
A preceding stage makes use of an input selector for switching between FM sound,
AM sound and mute state. The gain can be switched between 10 dB (normal) and 4 dB
(reduced).
相關(guān)PDF資料
PDF描述
TDA9885HN/V5 AM/FM, AUDIO/VIDEO DEMODULATOR, PQCC32
TDA9885T/V5 AM/FM, AUDIO/VIDEO DEMODULATOR, PDSO24
TDA9885TS/V5 AM/FM, AUDIO/VIDEO DEMODULATOR, PDSO24
TDA9886HN/V5 AM/FM, AUDIO/VIDEO DEMODULATOR, PQCC32
TDA9886T/V5 AM/FM, AUDIO/VIDEO DEMODULATOR, PDSO24
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
TDA9884TS 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:I2C-bus controlled multistandard alignment-free IF-PLL for mobile reception
TDA9884TS/V1 功能描述:調(diào)節(jié)器/解調(diào)器 MOBILE VIF AND SIF DEMODULATOR RoHS:否 制造商:Texas Instruments 封裝 / 箱體:PVQFN-N24 封裝:Reel
TDA9884TS/V1,112 功能描述:調(diào)節(jié)器/解調(diào)器 MOBILE VIF AND SIF RoHS:否 制造商:Texas Instruments 封裝 / 箱體:PVQFN-N24 封裝:Reel
TDA9884TS/V1,118 功能描述:調(diào)節(jié)器/解調(diào)器 MOBILE VIF AND SIF RoHS:否 制造商:Texas Instruments 封裝 / 箱體:PVQFN-N24 封裝:Reel
TDA9884TS/V1/S1,11 功能描述:調(diào)節(jié)器/解調(diào)器 MOBILE VIF AND SIF RoHS:否 制造商:Texas Instruments 封裝 / 箱體:PVQFN-N24 封裝:Reel
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