HSP50215 データシートの表示（PDF） - Intersil

部品番号

コンポーネント説明

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HSP50215

Digital UpConverter

Intersil 

HSP50215

SAMPLE FREQUENCY

ZERO

SYNCSEL

SYNCIN

WR CW3

START

EDGE

GEN

WR CW21

R

E

>G

RST

R

E

>G

IP(1:0)

30

2

EN

REG <

ACC

∑

EnNCO

(CARRIER NCO)

32

RESET

EDGE

GEN

> REG

SAMPCK

(MSB)

SHIFTER

> REG

† ALL REGISTERS ARE

CLOCKED AT REFLCK

12

4, 3, OR 2

FINE

PHASE

COARSE

PHASE

FIGURE 8. RE-SAMPLING NCO BLOCK DIAGRAM

Re-Sampling NCO Application Issues

1. Common clocking of the PUC and PDC:

Note that at a board level, the HSP50214 (PDC) and

HSP50215 (DUC) sample rate NCO’s typically utilize

different clocks. The DUC circuitry is clocked at the master

clock, REFCLK, rate. The PDC output circuitry runs off the

decimated sample rate. If a common sample clock is used

for both parts, then synchronization can be achieved by

scaling and/or truncating the PDC frequency control word to

match the PUC frequency control word. Powers of 2 are

handled by simply truncating the PDC frequency control

word to match the bit width of the DUC frequency control

word. If the PDC decimation factor is not power of 2, then

errors will accumulate.

2. Improving the NCO Accuracy

The Re-Sampler NCO frequency can be adjusted to

maintain phase and frequency lock to a reference clock, if

more accuracy is required.

Interpolation Filter

The Interpolation filter provides sampling rate conversion

from the shaping filter output rate to the final output sample

rate. The nulls in the interpolation filter frequency response

align with the interpolation images of the shaping filter. The

impulse response of the Interpolation filter is shown in

Figures 9A through 9C for an interpolate by 16 filter (the

interpolation ratio, L, is equal to 16). The Interpolation filter

has a pipeline delay of 3 coarse input samples plus 3

REFCLK cycles.

0

INTERPOLATION FILTER RESPONSE

-20

-40

-60

-80

-100

-120

512 1024 1536 2048 2560 3072 3584 4096

SAMPLE TIMES

FIGURE 9A. INTERPOLATION FILTER IMPULSE RESPONSE

L = 16; FOUT = 4096

0

INTERPOLATION FILTER RESPONSE

-20

-40

-60

-80

-100

-120

64 128 192 256 320 384 448

512

SAMPLE TIMES

FIGURE 9B. INTERPOLATION FILTER IMPULSE RESPONSE

L = 16; FOUT = 4096

0

-0.05

-0.1

-0.15 INTERPOLATION FILTER RESPONSE

-0.2

-0.25

-0.3

-0.35

-0.4

-0.45

-0.5

-0.55

-0.6

-0.65

-0.7

8

16 24 32 40 48 56 64

SAMPLE TIMES

FIGURE 9C. INTERPOLATION FILTER IMPULSE RESPONSE

L = 16; FOUT = 4096

3-430

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