V VIZIO P42HDTV10A, Service Manual

Page: 53 / 219

CONFIDENTIAL – DO NOT COPY Page 8- 21
File No. SG-0184
MT5111 Application:
MT5111 Functional Block Diagram
MT5111 is fully integrated single-chip 8-VSB , designed specifically for the digital terrestrial.
HDTV receivers . The chip is fully compliant with the ATSC A/53 digital TV standard.
MT5111 includes a 10-bit A/D converter , 8-VSB demodulator , TCM(Trellis-Coded Modulation).
Decoder . and Reed-Solomon Forward Error Correction decoder . Moreover , an internal
controller handles the acquisition and tracking to ensure the best receiving performance . The
internal controller communicates with the external host controller via the I2C-compatible
interface , and also provides direct control to the RF tuner via the second I2C-compatible
interface.
MT5111 accepts either the direct IF signals centered at 44MHZ or 43.75MHZ , or the low IF
signal Centered at 5.38MHZ . The center frequency of the incoming IF signal can also be
programmed to other frequencies for Various applications . An On-chip programmable
gain-controlled amplifier is designed to provide sufficient signal amplitude when the received RF
signal is weak . The If signal is first sampled by a 10-bit A/D converter . Afterward , the digitized
samples are further processed for adjacent channel interference rejection.
MT5111 measures the power level of the digitized sequence , and feeds the control voltages
back to the RF tuner and the IF amplifier respectively . The control voltages are converted to
analog signals through the on-chip 1-bit sigma-delta D/A converters plus the off-chip R-C
low-pass filters . The automatic gain control keeps the received power level at a desired level
and maximizes the received SNR .