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Soft-Clipping (Compression) Circuit

V

H +

R2

V

CH )

R1

V

IN

R1 ) R2

(1)

V

L +

R4

V

CL )

R3

V

IN

R3 ) R4

(2)

OPA698

V

H

V

L

R

4

2k

Ω

R

3

1k

Ω

24.9

Ω

R

2

2k

Ω

V

CL

-1V

V

CH

+1V

V

OUT

V

IN

R

1

1k

Ω

S0043-01

Time (100ns/div)

3

2

1

0

-1

-2

-3

V

IN

V

OUT

G051

High-Speed Schmitt Trigger

OPA698M

SGLS287A – MAY 2005 – REVISED MARCH 2006

TYPICAL APPLICATIONS (continued)

If the negative excursion of the rectified signal is not desired, it can easily be removed by replacing the OPA693

with the OPA698 configured as a difference amplifier with VL connected to ground and VH left floating.

Figure 59 shows a soft-clipping circuit. As soon as the input voltage exceeds either VCH or VCL, the limiting

voltages are driven by Equation 1 and Equation 2.

As the amplifier is operating in the limiting mode, the output voltage is compressed with a gain of R1+R2/R1 for

the positive excursion above VCH and by a gain of R3+R4/R3 for the negative excursion below VCL. Figure 60

shows a 5 VPP on the input being compressed above ±1 V with a compression gain of one third.

Figure 59. Soft-Clipping Circuit

Figure 60. Soft-Clipping With A Gain of 1/3 Above the Clamp Level (±1 V)

Figure 61 shows a high-speed Schmitt Trigger. The output levels are precisely defined and the switching time is

exceptional. The output voltage swings between VH and VL.

20

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