AD1890_15 Datasheet, PDF (9/20 Pages) Analog Devices – SamplePort Stereo Asynchronous Sample Rate Converters

AMP
PHASE
TIME
SUBFILTER COEFFICIENTS
ALIGNED TO THE LEFT
Tsin = 1/Fsin
AD1890/AD1891
Fsin/2
DELAY = NOMINAL
FREQ
Fsin/2
DELAY = NOMINAL
Fsin/2
DELAY = NOMINAL – .25/Fsin
Fsin/2
DELAY = NOMINAL – .5/Fsin
Fsin/2
DELAY = NOMINAL – .75/Fsin
Figure 3. Four Polyphase Subfilters Realigned to Coarse Time Grid
INPUT
SIGNAL
PARALLEL POLYPHASE
FILTER BANK
POLYPHASE FILTER 1
POLYPHASE FILTER 2
POLYPHASE FILTER 3
POLYPHASE FILTER 4
POLYPHASE FILTER 5
POLYPHASE FILTER 6
POLYPHASE FILTER 7
N TO 1
MUX
OUTPUT
SIGNAL
The full set of subfilters can be considered to form a parallel
bank of “polyphase” filters which have decrementing, linear
phase group delays. All of the polyphase filters conceptually pro-
cess the input signal simultaneously, as illustrated in Figure 4, at
the input sample rate.
POLYPHASE FILTER N-1
POLYPHASE FILTER N
SELECT
SAMPLE
CLOCK
TRACKING
CIRCUIT
Figure 4. Polyphase Filter Bank Model—Conceptual Block
Diagram
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