AD7400 Analog Devices, AD7400 Datasheet - Page 16

• Manufacturer Part Number: AD7400
• Description: Isolated Sigma-Delta Modulator
• Manufacturer: Analog Devices

Specifications of AD7400

• Resolution (bits): 16bit
• # Chan: 1
• Sample Rate: 10MSPS
• Interface: Ser
• Analog Input Type: Diff-Uni
• Ain Range: ± 0.2 V Diff,0.4 V p-p
• Adc Architecture: Sigma-Delta Modulator
• Pkg Type: SOIC

AD7400
always @ (posedge word_clk or posedge reset)
if(reset)
else
/* Clock the Sinc output into an output
register
WORD_CLK = output word rate
*/
always @ (posedge word_clk)
begin
DATA[15] <= diff3[23];
DATA[14] <= diff3[22];
DATA[13] <= diff3[21];
DATA[12] <= diff3[20];
DATA[11] <= diff3[19];
DATA[10] <= diff3[18];
begin
acc3_d2 <= 0;
diff1_d <= 0;
diff2_d <= 0;
diff1 <= 0;
diff2 <= 0;
diff3 <= 0;
end
begin
diff1 <= acc3 - acc3_d2;
diff2 <= diff1 - diff1_d;
diff3 <= diff2 - diff2_d;
acc3_d2 <= acc3;
diff1_d <= diff1;
diff2_d <= diff2;
end
Figure 27. Clocking Sinc Output into an Output Register
WORD_CLK
DIFF3
DATA
Rev. E | Page 16 of 20
DATA[9]
DATA[8]
DATA[7]
DATA[6]
DATA[5]
DATA[4]
DATA[3]
DATA[2]
DATA[1]
DATA[0]
end
endmodule
Figure 28. SNR vs. Decimation Rate for Different Filter Types
90
80
70
60
50
40
30
20
10
0
1
<= diff3[17];
<= diff3[16];
<= diff3[15];
<= diff3[14];
<= diff3[13];
<= diff3[12];
<= diff3[11];
<= diff3[10];
<= diff3[9];
<= diff3[8];
10
DECIMATION RATE
100
SINC
SINC
SINC
3
2
1
1k