8.3.6.2.2 Low-Latency Filters

For applications where low latency with minimal phase deviation (within the audio band) is critical, the low-

latency decimation filters on the PCM182x can be used. The device supports these filters with a group delay of

section provides the filter performance specifications and various plots for all supported output sampling rates for

the low-latency filters.

8.3.6.2.2.1 Sampling Rate: 16 kHz or 14.7 kHz

Figure 8-23 shows the magnitude response and Figure 8-24 shows the pass-band ripple and phase deviation for

a decimation filter with a sampling rate of 16 kHz or 14.7 kHz. Table 8-15 lists the specifications for a decimation

filter with a 16-kHz or 14.7-kHz sampling rate.

0

0.4

0.8

1.2

1.6

2

2.4

2.8

3.2

3.6

4

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

10

D002

Figure 8-23. Low-Latency Decimation Filter

Magnitude Response

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

-0.5

-0.5

-0.4

-0.4

-0.3

-0.3

-0.2

-0.2

-0.1

-0.1

0

0

0.1

0.1

0.2

0.2

0.3

0.3

0.4

0.4

0.5

0.5

D002

Pass-Band Ripple

Phase Deviation

Figure 8-24. Low-Latency Decimation Filter Pass-

Band Ripple and Phase Deviation

Table 8-15. Low-Latency Decimation Filter Specifications

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Pass-band ripple

–0.05

0.05

dB

Stop-band attenuation

87.3

dB

Group delay or latency

7.6

Group delay deviation

–0.022

0.022

Phase deviation

–0.21

0.25

Degrees

PCM1820, PCM1821

SBASA61 – DECEMBER 2020

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