TDA18218HN/C1,557 NXP Semiconductors, TDA18218HN/C1,557 Datasheet - Page 5

• Manufacturer Part Number: TDA18218HN/C1,557
• Description: IC TV SILICON TUNER 48HVQFN
• Manufacturer: NXP Semiconductors
• Type: Silicon Tunerr

Specifications of TDA18218HN/C1,557

• Applications: Receivers, Set-Top Boxes, TV
• Mounting Type: Surface Mount
• Package / Case: 48-VQFN Exposed Pad, 48-HVQFN, 48-SQFN, 48-DHVQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 935287721557

NXP Semiconductors
TDA18218HN_1
Product data sheet
8.1 AGC1 stage
8.2 AGC2 stage
8.3 IF AGC
and 8 MHz channel bandwidths). The TDA18218HN requires a single 16 MHz crystal for
clock generation, a 16 MHz differential sine wave clock reference is available to drive a
channel decoder.
The TDA18218HN embeds 2 different RF amplifiers with internal gain control.
The first stage, AGC1, behaves like a LNA (Low noise amplifier); its gain can take 4
different values (15 dB, 12 dB, 9 dB and 6 dB). Purpose of this amplifier is to ensure a low
noise figure for the tuner.
In order to optimize noise and linearity performances an internal level detector selects the
appropriate gain:
The strategy of the level detection is a proprietary algorithm from NXP, managed by the
driver.
It should be noted that:
The second stage, AGC2, is also an amplifier with a gain controlled thanks to a level
detector.
The gain is controlled between 12 dB and +16.4 dB, it is adapted by steps of 0.2 dB.
It should be noted that:
The strategy of the level detection is a proprietary algorithm from NXP, managed by the
driver.
Finally, in order to adapt the tuner output level, a last amplifier is used (IF AGC). This
amplifier delivers the appropriate level to the DVB-T channel decoder. The output level is
therefore controlled thanks to the DC voltage applied on VIFAGC pin. This voltage is
commonly delivered by the channel decoder.
1. The level detector measures the signal level within the complete RF frequency range,
2. The level control is always operating.
1. The level control is always operating. Consequently, this amplifier is responsible for
2. The level detector measures the signal level within the complete RF frequency range
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•
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If the signal level at the tuner is low, the gain is set to the maximum value (15 dB).
If the signal level at the tuner input is high, the gain is set to the minimum value (6 dB).
In between the gain is set to an intermediate value 12 dB or 9 dB.
i.e. from 50 MHz to 870 MHz. Consequently, AGC1 gain is adapted to the complete
RF power. If a strong signal is present at the tuner input, it will determine AGC1 gain
(even if it is not the wanted signal). This concept prevents the tuner from overloading.
adapting the daily level changes.
(same as AGC1)
Rev. 01 — 8 July 2009
TDA18218HN
DVB-T Silicon Tuner IC
© NXP B.V. 2009. All rights reserved.
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