AN207 Vishay Intertechnology, AN207 Datasheet - Page 11

• Manufacturer Part Number: AN207
• Description: 15-ns DG611 Switch Family Combines Benefits of CMOS And Dmos
• Manufacturer: Vishay Intertechnology

Audio Mixer
Switching audio inputs at the summing junction of an op amp
eliminates audio distortion due to on-resistance modulation.
This is because when turned on, the analog switch channel
stays at a constant 0 V. Unfortunately, any charge injection
Document Number: 70605
03-Aug-99
V
V
V
V
Ref
1
2
3
4
DAC
FIGURE 19. Low Distortion Audio Mixer Eliminates
R
R
FB
T/H
V
I
OUT
DG612
OUT
Switching Noise
–
1
R
/
R
2
F
DG613
(V
1
...
R
F
V
4
)
FIGURE 18. DAC Deglitcher
V
OUT
V
OUT
present during switching at the high impedance Op Amp input
gets amplified and can cause large output spikes. These
switching spikes usually cause clicking and/or popping noises.
Thanks to its low charge injection properties, the DG61X family
virtually eliminates this type of switching noise. A small
snubber network connected across the op amp inputs further
reduces any high-speed glitches.
b) Off-State
a) On-State
S
1 pA
S
Deglitched
FIGURE 20. Static Switch Models
C
S(off)
3 pF
V
V
OUT
T/H
OUT
I
r
S(off)
DS(on)
18
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C
0.5 pF
1 pA
SD(off)
Vishay Siliconix
C
10 pF
S(on)
1 pA
I
D(on)
C
2 pF
AN207
D(off)
D
I
D(off)
D
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