GDC21D003

The VSB Receiver(GDC21D003) is an ATSC compliant single chip communications GDC21D003 that synchronizes, equalizes, and corrects errors of ATSC 8/16 VSB and MMDS (Multichannel Multipoint Distribution System) 2/4/8/16 VSB modulated signal.

The on-chip 10-bit 10.76Msps Analog-to-Digital Converter has an input sample-and-hold amplifier. By implementing a multistage pipelined architecture with output correction logic, the ADC offers accurate performance and guarantees no missing codes over the full operating temperature. Clock divider GDC21D003 output clock of external VCXO and generates symbol clock (CLKFS) and ADCCLK. The CLKFS has 10.76MHz frequency as symbol frequency used in DTV transmitter, ADCCLK GDC21D003 is used for external A/D converter. At this time, if you use digital signal as input of chip,
CLKFS or ADCCLK are used for external A/D converter clock.

Synchronizer removes DC entered from transmitter and DC generated by analog circuit used in receiver. Also it checks gain of input signal and sends it to demodulator, detects polarity, and corrects it. GDC21D003 recovers Data Segment Sync period and Field Sync period entered from transmitter. GDC21D003 detects VSB mode of current input signal and removes NTSC co-channel interference in channel. Equalizer corrects linear distortion created during transmission. GDC21D003 uses Least-Mean-Square algorithm and has decision feedback equalizer structure. It uses adaptive filter having coefficient update structure consisted of multiplier, adder, and memory structure in every tap.

Phase Tracker compensates phase distortion due to phase noise and it consists of gain correction loop for gain error, offset correction loop for offset error, and phase correction loop for phase error. Channel Decoder consists of Viterbi Decoder, Convolutional Deinterleaver, Reed-Solomon Decoder, Data Derandomizer, and etc. GDC21D003 decodes ATSC 8/16 VSB signal and MMDS 2/4/8/16 VSB signal. Also GDC21D003 has internal segment error counter that send out the number of segment errors per second and offers tri-state parallel/serial Transport Demultiplexer interface.