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CXD2467Q

Digital Signal Driver/Timing Generator

Sony Semiconductor 

CXD2467Q

The various signal processing functions are described below. Note that the coefficients used for each

arithmetic operation are set through the parallel I/F block. See the individual descriptions of each parallel I/F

block item for a detailed description of the parallel I/F block.

(a) User gain block

This block performs multiplication processing as the user gain adjustment. Multiplication is performed as

follows using the 8-bit data a[7:0] input to this IC and an 8-bit coefficient b[7:0].

c[15:0] = a[7:0] × b[7:0]

The upper 12 bits c[15:4] of the arithmetic results are output. Next, the c[4] value is checked and rounding is

performed to 11 bits. Further, the MSB of the rounded 11 bits is checked, clipping is performed to prevent

overflow, and the lower 10 bits are output. Note that since the coefficient has 8 bits and the 5th bit of the

arithmetic results is rounded, the maximum gain by this operation is 255/32 = 7.96875 times and this can be

varied in 256 steps. The arithmetic coefficient is shared by R, G and B, and the initial value is 020h.

Coefficient

b[7:0]

8

Input

8

a[7:0]

a×b

12

c[15:4]

Rounding

and

clipping

10

Output

(b) User bright block

This block performs addition and subtraction processing as the user bright adjustment. The 10 bits of data

a[9:0] output from the user gain block, a 10-bit coefficient b[9:0], and a 1-bit code are used as the inputs to

perform arithmetic processing with an accuracy of 1 bit. Addition is performed when the code = 0, and

subtraction when the code = 1. However, when performing subtraction, set an arithmetic coefficient that is the

twos complement of the number to be subtracted.

The initial adder performs the following addition:

c[10:0] = a[9:0] + b[9:0]

Then, overflow and underflow are judged according to c[10] which is the MSB of the arithmetic results and the

code data value. 3FFh is output when overflow occurs, and 000h when underflow occurs. Note that the

arithmetic coefficient and code are shared by R, G and B, and the initial values are 000h and 0h, respectively.

Coefficient

b[9:0] 10

Code

Input 10

a[9:0]

a+b

11

c[10:0]

Clipping

10

Output

– 17 –

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