AD1862

–10–

REV. A

HIGH-RESOLUTION SIGNAL PROCESSING

Figure 14 illustrates the AD1862 combined with the DSP56000.

In high-resolution applications, the combination of the 24-bit

architecture of the DSP56000 and the low noise and high reso-

lution of the AD1862 can produce a high-resolution, low-noise

system.

As shown in Figure 14, the clock signal supplied by the DSP

processor must be inverted to be compatible with the input of

the AD1862. The exact architecture of the output low-pass filter

depends on the sample rate of the output data. In general, the

higher the oversampling rate, the fewer number of filter poles

are required to prevent aliasing.

The 20-bit resolution is particularly suitable for professional au-

dio, mixing or equalization equipment. Its resolution allows

24 dB of equalization to be performed on 16-bit input words

without signal truncation. Furthermore, up to sixteen 16-bit in-

put words can be mixed and output directly to the AD1862. In

this case, no loss of signal information would be encountered.

1

2

3

4

5

6

7

89

10

11

12

13

14

15

16

LOW PASS

FILTER

OUTPUT

VOLTAGE

0.1

µF

0.1

µF

0.1

µF

5V

DIGITAL

SUPPLY

–

12V

ANALOG

SUPPLY

–

12V

ANALOG

SUPPLY

0.1

µF

10

µF

AD846

ANALOG

COMMON

DIGITAL

COMMON

5V

DIGITAL

SUPPLY

V

CC

SCK

SC2

STD

V

DD

DSP56001

1

µF

AD1862

V

+

S

NR

2

ADJ

NR

1

AGND

I

OUT

R

F

DGND

V

+

L

LE

V

–

S

TRIM

CLK

DATA

V

–

L

V

–

S

Figure 14. DSP56001 and AD1862 Produce High Resolution Signal Processing System