MAX12527 Datasheet, PDF (21/28 Pages) Maxim Integrated Products – Dual, 65Msps, 12-Bit, IF/Baseband ADC

Dual, 65Msps, 12-Bit, IF/Baseband ADC
BINARY-TO-GRAY CODE CONVERSION
1) THE MOST SIGNIFICANT GRAY-CODE BIT IS THE SAME
AS THE MOST SIGNIFICANT BINARY BIT.
D11
D7
D3
D0
0111 0100 1100
0
BIT POSITION
BINARY
GRAY CODE
2) SUBSEQUENT GRAY-CODE BITS ARE FOUND ACCORDING
TO THE FOLLOWING EQUATION:
GRAY_X = BINARY_X + BINARY_{X + 1}
WHERE + IS THE EXCLUSIVE OR FUNCTION (SEE TRUTH
TABLE BELOW) AND X IS THE BIT POSITION:
GRAY₁₀ = BINARY₁₀ + BINARY₁₁
GRAY₁₀ = 1 + 0
GRAY₁₀ = 1
D11
0+111
01
D7
0100
D3
D0
1100
BIT POSITION
BINARY
GRAY CODE
3) REPEAT STEP 2 UNTIL COMPLETE:
GRAY₉ = BINARY₉ + BINARY₁₀
GRAY₉ = 1 + 1
GRAY₉ = 0
D11
01+11
01 0
D7
0100
D3
D0
1100
BIT POSITION
BINARY
GRAY CODE
4) THE FINAL GRAY-CODE CONVERSION IS:
D11
D7
0111 0100
0100 1110
D3
D0
1100
1010
BIT POSITION
BINARY
GRAY CODE
GRAY-TO-BINARY CODE CONVERSION
1) THE MOST SIGNIFICANT BINARY BIT IS THE SAME AS THE
MOST SIGNIFICANT GRAY-CODE BIT.
D11
D7
D3
D0
0100 1110 1010
0
BIT POSITION
GRAY CODE
BINARY
2) SUBSEQUENT BINARY BITS ARE FOUND ACCORDING TO
THE FOLLOWING EQUATION:
BINARY_X = BINARY_X+1 + GRAY_X
WHERE + IS THE EXCLUSIVE OR FUNCTION (SEE TRUTH
TABLE BELOW) AND X IS THE BIT POSITION:
BINARY₁₀ = BINARY₁₁ + GRAY₁₀
BINARY₁₀ = 0 + 1
BINARY₁₀ = 1
D11
0 100
+
01
D7
1110
D3
D0
1010
BIT POSITION
GRAY CODE
BINARY
3) REPEAT STEP 2 UNTIL COMPLETE:
BINARY₉ = BINARY₁₀ + GRAY₉
BINARY₉ = 1 + 0
BINARY₉ = 1
D11
01 00
+
01 1
D7
1110
D3
D0
1010
BIT POSITION
GRAY CODE
BINARY
4) THE FINAL BINARY CONVERSION IS:
D11
D7
0100 1110
0111 0100
D3
D0
1010
1100
BIT POSITION
GRAY CODE
BINARY
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.
EXCLUSIVE OR TRUTH TABLE
AB
Y=A+B
00
0
01
1
10
1
11
0
Figure 8. Binary-to-Gray and Gray-to-Binary Code Conversion
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