CS42438-DMZR(2006) 데이터 시트보기 (PDF) - Cirrus Logic

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CS42438-DMZR
(Rev.:2006)

108 dB, 192 kHz 6-In, 8-Out TDM CODEC

Cirrus Logic 

8. EXTERNAL FILTERS

CS42438

8.1 ADC Input Filter

The analog modulator samples the input at 6.144 MHz (internal MCLK=12.288 MHz). The digital filter will

reject signals within the stopband of the filter. However, there is no rejection for input signals which are mul-

tiples of the digital passband frequency (n × 6.144 MHz), where n=0,1,2,... Refer to Figures 20 and 21 for

a recommended analog input filter that will attenuate any noise energy at 6.144 MHz, in addition to providing

the optimum source impedance for the modulators. Refer to Figures 22 and 23 for low-cost, low-component-

count passive input filters. The use of capacitors that have a large voltage coefficient (such as general-pur-

pose ceramics) must be avoided since these can degrade signal linearity

634 Ω

100k Ω

4.7 µF

470 pF

C0G

-

+

VA

100k Ω

10k Ω

91 Ω

634 Ω

100k Ω

0.1 µF

100 µF 332 Ω

634 Ω

470 pF

C0G

-

+

91 Ω

2700 pF

C0G

ADC1-3

AINx+

AINx-

Figure 20. Single to Differential Active Input Filter

100 kΩ

VA

100 kΩ

4.7 µF

100 kΩ

634 Ω

470 pF

C0G

-

91 Ω

+

2700 pF

C0G

ADC1-2

AIN1+,2+,3+,4+

4.7 µF

AIN1-,2-,3-,4-

100 kΩ

VA

100 kΩ

4.7 µF

100 kΩ

100 kΩ

VA

100 kΩ

4.7 µF

100 kΩ

470 pF

634 Ω

C0G

-

91 Ω

+

470 pF

634 Ω

C0G

-

91 Ω

+

2700 pF

C0G

ADC3

AIN5A,6A

2700 pF

C0G

AIN5B,6B

Figure 21. Single-Ended Active Input Filter

50

DS646F1

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