SM-SX100 (serv.man2) - Sharp Audio Service Manual (repair manual). Page 14

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If any 1-bit signal is produced through the operation of the 

 modulation, the quantized noise is expelled to the high range.

This is well known as "noise shaping", and it is used to reduce the quantized noise of the target frequency band (example:
audible band). As the operation of "primary 

 modulation" is described using Fig. 14-1, it is well known that the reduction

effect of the quantized noise is increased as the number of the order of the 

 modulation is increased.

Quantized noise

Audible band

0

fs/6

Frequency

7th order

5th order

3th order

0th order

The circuit here used to produce the 1-bit signal is practiced of "7th order 

 modulation algorithm" as shown in Fig. 14-

2. The strong noise shaping is applied to assure the wide dynamic range in the audible range.

Q

Q

Z

–1

Z

–1

Z

–1

Z

–1

Z

–1

Y

Output

Quantization

Adder

Integrator

Multiplier

Delay unit

Quantizer (–1 or +1)

Input

X

a

1

b

1

a

2

a

3

b

2

a

4

a

5

a

6

b

3

"7th order 

 modulation LSI" gained by integrating the signal process circuit into one chip is shown in Fig. 14-3. As well

as the LSI can independently generate the 1-bit signals, the input terminal is provided to apply the feedback of the 
modulation from the external in order to show the performance with the amplifying operation.