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參數(shù)資料
| 型號： | AD1895AYRSRL |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 消費家電 |
| 英文描述： | 192 kHz Stereo Asynchronous Sample Rate Converter |
| 中文描述： | SPECIALTY CONSUMER CIRCUIT, PDSO28 |
| 封裝： | PLASTIC, MO-150AH, SSOP-28 |
| 文件頁數(shù)： | 18/24頁 |
| 文件大?。?/td> | 816K |
| 代理商： | AD1895AYRSRL |
REV. A
AD1895
–18–
The digital servo loop is essentially a ramp filter that provides
the initial pointer to the address in RAM and ROM for the start
of the FIR convolution. The RAM pointer is the integer output
of the ramp filter while the ROM is the fractional part. The
digital servo loop must be able to provide excellent rejection of
jitter on the f
S_IN
and f
S_OUT
clocks as well as measure the arrival
of the f
S_OUT
clock within 4.97 ps. The digital servo loop will
also divide the fractional part of the ramp output by the ratio of
f
S_IN
/f
S_OUT
for the case when f
S_IN
> f
S_OUT
, to dynamically alter
the ROM coefficients.
The digital servo loop is implemented with a multirate filter. To
settle the digital servo loop filter quicker upon start-up or a change
in the sample rate, a “fast mode” was added to the filter. When
the digital servo loop starts up or the sample rate is changed, the
digital servo loop kicks into “fast mode” to adjust and settle
on the new sample rate. Upon sensing the digital servo loop
settling down to some reasonable value, the digital servo loop
will kick into “normal” or “slow mode.” During “fast mode”
the MUTE_OUT signal of the sample rate converter is asserted
to let the user know that they should mute the sample rate
converter to avoid any clicks or pops. The frequency response of
the digital servo loop for “fast mode” and “slow mode” are
shown in Figure 8.
The FIR filter is a 64-tap filter in the case of f
S_OUT
≥
f
S_IN
and is
(f
S_IN
/f
S_OUT
)
×
64 taps for the case when f
S_IN
> f
S_OUT
. The FIR
filter performs its convolution by loading in the starting address
of the RAM address pointer and the ROM address pointer
from the digital servo loop at the start of the f
S_OUT
period.
The FIR filter then steps through the RAM by decrementing its
address by 1 for each tap, and the ROM pointer increments its
address by the (f
S_OUT
/f
S_IN
)
×
2
20
ratio for f
S_IN
> f
S_OUT
or 2
20
for f
S_OUT
≥
f
S_IN
. Once the ROM address rolls over, the con-
volution is completed. The convolution is performed for both
the left and right channels, and the multiply accumulate circuit
used for the convolution is shared between the channels.
The f
S_IN
/f
S_OUT
sample rate ratio circuit is used to dynamically
alter the coefficients in the ROM for the case when f
S_IN
>
f
S_OUT
. The ratio is calculated by comparing the output of an
f
S_OUT
counter to the output of an f
S_IN
counter. If f
S_OUT
>
f
S_IN
, the ratio is held at one. If f
S_IN
> f
S_OUT
, the sample rate
ratio is updated if it is different by more than two f
S_OUT
periods
from the previous f
S_OUT
to f
S_IN
comparison. This is done to
provide some hysteresis to prevent the filter length from oscillat-
ing and causing distortion.
10
0
–
10
–
20
–
30
–
40
–
50
–
60
–
70
–
80
–
90
–
100
–
110
–
120
–
130
–
140
–
150
–
160
–
170
–
180
–
190
–
200
–
210
–
220
0.01
0.1
1
10
FREQUENCY
–
Hz
100
1e3
1e4
1e5
SLOW MODE
FAST MODE
Figure 8. Frequency Response of the Digital Servo Loop. f
S_IN
is the X-Axis, f
S_OUT
= 192 kHz, Master Clock
Frequency Is 30 MHz
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD1895AYRSZ | 功能描述:IC CONV SAMPLE RATE ASYNC 28SSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻處理 系列:- 其它有關(guān)文件:STA321 View All Specifications 標準包裝:1 系列:Sound Terminal™ 類型:音頻處理器 應(yīng)用:數(shù)字音頻 安裝類型:表面貼裝 封裝/外殼:64-LQFP 裸露焊盤 供應(yīng)商設(shè)備封裝:64-LQFP EP（10x10） 包裝:Digi-Reel® 其它名稱:497-11050-6 |
| AD1895AYRSZRL | 功能描述:IC SAMP-RATEHP/CONV 24BIT 28SSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻處理 系列:- 其它有關(guān)文件:STA321 View All Specifications 標準包裝:1 系列:Sound Terminal™ 類型:音頻處理器 應(yīng)用:數(shù)字音頻 安裝類型:表面貼裝 封裝/外殼:64-LQFP 裸露焊盤 供應(yīng)商設(shè)備封裝:64-LQFP EP（10x10） 包裝:Digi-Reel® 其它名稱:497-11050-6 |
| AD1895YRS | 制造商:Rochester Electronics LLC 功能描述:192KHZ 8:1 STEREO ASYNC S - Bulk |
| AD1895YRSRL | 制造商:Rochester Electronics LLC 功能描述:192KHZ 8:1 STEREO ASYNC S - Bulk |
| AD1896 | 制造商:AD 制造商全稱:Analog Devices 功能描述:192 kHz Stereo Asynchronous Sample Rate Converter |
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