Maxim MAX12527 TV Converter Box User Manual


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MAX12527
Dual, 65Msps, 12-Bit, IF/Baseband ADC
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BINARY-TO-GRAY CODE CONVERSION
1) THE MOST SIGNIFICANT GRAY-CODE BIT IS THE SAME
AS THE MOST SIGNIFICANT BINARY BIT.
0111 0100 1100 BINARY
GRAY CODE0
2) SUBSEQUENT GRAY-CODE BITS ARE FOUND ACCORDING
TO THE FOLLOWING EQUATION:
D11 D7 D3 D0
GRAY
X
= BINARY
X
+
BINARY
X + 1
BIT POSITION
0111 0100 1100 BINARY
GRAY CODE0
D11 D7 D3 D0
BIT POSITION
GRAY
10
= BINARY
10
BINARY
11
GRAY
10
= 1 0
GRAY
10
= 1
1
3) REPEAT STEP 2 UNTIL COMPLETE:
01 11 0100 1100 BINARY
GRAY CODE0
D11 D7 D3 D0
BIT POSITION
GRAY
9
= BINARY
9
BINARY
10
GRAY
9
= 1 1
GRAY
9
= 0
10
4) THE FINAL GRAY-CODE CONVERSION IS:
0111 0100 1100 BINARY
GRAY CODE0
D11 D7 D3 D0
BIT POSITION
100 1101 1010
GRAY-TO-BINARY CODE CONVERSION
1) THE MOST SIGNIFICANT BINARY BIT IS THE SAME AS THE
MOST SIGNIFICANT GRAY-CODE BIT.
2) SUBSEQUENT BINARY BITS ARE FOUND ACCORDING TO
THE FOLLOWING EQUATION:
D11 D7 D3 D0
BINARY
X
= BINARY
X+1
BIT POSITION
BINARY
10
= BINARY
11
GRAY
10
BINARY
10
= 0 1
BINARY
10
= 1
3) REPEAT STEP 2 UNTIL COMPLETE:
4) THE FINAL BINARY CONVERSION IS:
0100 1110 1010
BINARY
GRAY CODE
D11 D7 D3 D0
BIT POSITION
0 BINARY
GRAY CODE0100 11 011010
BINARY
9
= BINARY
10
GRAY
9
BINARY
9
= 1 0
BINARY
9
= 1
GRAY
X
01001110 1010
BINARY
GRAY CODE
0
D11 D7 D3 D0
BIT POSITION
1
01 00 1110 1010
BINARY
GRAY CODE
0
D11 D7 D3 D0
BIT POSITION
11
0111 0100 1100
AB Y=AB
00
01
10
11
0
1
1
0
EXCLUSIVE OR TRUTH TABLE
WHERE IS THE EXCLUSIVE OR FUNCTION (SEE TRUTH
TABLE BELOW) AND X IS THE BIT POSITION:
+
WHERE IS THE EXCLUSIVE OR FUNCTION (SEE TRUTH
TABLE BELOW) AND X IS THE BIT POSITION:
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
FIGURE 8 SHOWS THE GRAY-TO-BINARY AND BINARY-TO-GRAY
CODE CONVERSION IN OFFSET BINARY FORMAT. THE OUTPUT
FORMAT OF THE MAX12527 IS TWO'S-COMPLEMENT BINARY,
HENCE EACH MSB OF THE TWO'S-COMPLEMENT OUTPUT CODE
MUST BE INSERTED TO REFLECT TRUE OFFSET BINARY FORMAT.
Figure 8. Binary-to-Gray and Gray-to-Binary Code Conversion
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