NCY9100

http://onsemi.com

6

Figure 6 shows how the circuit is hooked up to realize an

both the rectifier and the

DG cell. When the input signal

drops by 6.0 dB, the gain control current will drop by a factor

of 2, and so the gain will drop 6.0 dB. The output level at

expansion.

−

+

GAIN +

2

NOTE:

*EXTERNAL COMPONENTS

DG

Figure 6. Basic Expander

Figure 7 shows the hook−up for a compressor. This is

essentially an expandor placed in the feedback loop of the op

amp. The

DG cell is setup to provide AC feedback only, so

output of the op amp. The output will bias to:

30kW

1.8V

The output of the expander will bias up to:

30kW

1.8V + 3.0V

The output will bias to 3.0 V when the internal resistors are

DC bias to any desired value.

NOTE: GAIN +

1

2

*EXTERNAL COMPONENTS

VOUT

DG

*

Figure 7. Basic Compressor

*

−

+

Circuit Details − Rectifier

Figure 8 shows the concept behind the full−wave

averaging rectifier. The input current to the summing node

amp. If we can mirror the op amp output current into a

unipolar current, we will have an ideal rectifier. The output

the gain control current.

V+

Figure 8. Rectifier Concept

10kW

−

+