
TMC22x5yA
PRODUCT SPECIFICATION
44
TMC22x5yA Functional Description
Input Processor
The input processor selects between the two external video 
sources on VIDEO A and VIDEO B. If the TRS stripper or 
GRS stacker is active, then the user must select the input 
with either the GRS (in genlock mode) or with the embedded 
TRS words as output VA. If the input data are separate luma 
and chroma or Y and C
B
C
R
 data the input processor must be 
programmed to put the chrominance or C
B
C
R
 onto output 
VB and the luminance or Y onto VA. 
To ensure that the chrominance data or the C
B
C
R
 data are in 
two’s complement arithmetic format, the register bit MSBI 
inverts the msb of the DB input. For composite inputs, the 
IPCMSB register bit should be set LOW, as the ABMUX 
register bit is used to select the input(s) to the comb filter.
Bandsplit Filter (BSF)
In its simple mode of operation, the TMC22x5yA uses a 
complementary bandsplit filter, instead of a notch filter for 
the luma and a bandpass for the chroma. The notch and 
bandpass filter technique, removes frequency bands from the 
composite video spectrum which can never be retrieved. 
The complementary bandsplit filter technique, shown in 
Figure 12, allows the decoded component video signals to be 
re-encoded into a composite video signal with the minimum 
of losses to the composite video spectrum.
Figure 12. Complementary Bandsplit Filter
The complementary bandsplit filter separates the base band 
composite video into two bands by passing it through a low 
pass filter and subtracting the low pass (luma) data from the 
composite video to produce the high pass (chroma) data. As 
the base bandwidths and subcarrier frequencies of the differ-
ent NTSC and PAL video formats are so different, and the 
decoder has to be capable of working over a large frequency 
range, it is necessary to provide two low pass filters. These 
filters are selectable by the BSFSEL register bit and are inde-
pendent of the video standard. A comparison of the different 
data rates to normalized subcarrier frequencies is provided in 
Table 2.
The complementary bandsplit low pass frequency response 
is shown in Figure 13 and Figure 14.
LPF
Input
65-22x5y-53
LPF Output
HPF Output
–
Figure 11. Input Processor
ICPMSB ABMUX
CKSEL
TBLK
TDEN
IP8B
IPMUX
x
TRS Stripper (D1/D2/D3)
and
GRS Stacker (TMC22071)
MSB
Invert
2:2 MUX
2:2 MUX
VA
VB
DA
DB
VideoA
VideoB
Primary Data
to Comb Filter
Secondary Data
to Comb Filter
Input Processor Control Register
msb
lsb
65-22x5y-52