- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄372105 > SA571D (NXP SEMICONDUCTORS) Ceramic Multilayer Capacitor; Capacitance:3.9pF; Capacitance Tolerance:+/- 0.5 pF; Working Voltage, DC:50V; Dielectric Characteristic:C0G/NP0; Package/Case:0603; Series:VJ; Features:Multilayer Ceramic Chip Capacitor PDF資料下載
參數(shù)資料
| 型號(hào)： | SA571D |
| 廠商： | NXP SEMICONDUCTORS |
| 元件分類： | 通信及網(wǎng)絡(luò) |
| 英文描述： | Ceramic Multilayer Capacitor; Capacitance:3.9pF; Capacitance Tolerance:+/- 0.5 pF; Working Voltage, DC:50V; Dielectric Characteristic:C0G/NP0; Package/Case:0603; Series:VJ; Features:Multilayer Ceramic Chip Capacitor |
| 中文描述： | SPECIALTY TELECOM CIRCUIT, PDSO16 |
| 文件頁(yè)數(shù)： | 5/11頁(yè) |
| 文件大小： | 143K |
| 代理商： | SA571D |
Philips Semiconductors
Product specification
SA571
Compandor
1997 Aug 14
5
This paper describes an inexpensive integrated circuit, the SA571
Compandor, which offers a pair of high performance gain control
circuits featuring low distortion (<0.1%), high signal-to-noise ratio
(90dB), and wide dynamic range (110dB).
CIRCUIT BACKGROUND
The SA571 Compandor was originally designed to satisfy the
requirements of the telephone system. When several telephone
channels are multiplexed onto a common line, the resulting
signal-to-noise ratio is poor and companding is used to allow a wider
dynamic range to be passed through the channel. Figure 5
graphically shows what a compandor can do for the signal-to-noise
ratio of a restricted dynamic range channel. The input level range of
+20 to -80dB is shown undergoing a 2-to-1 compression where a
2dB input level change is compressed into a 1dB output level
change by the compressor. The original 100dB of dynamic range is
thus compressed to a 50dB range for transmission through a
restricted dynamic range channel. A complementary expansion on
the receiving end restores the original signal levels and reduces the
channel noise by as much as 45dB.
The significant circuits in a compressor or expander are the rectifier
and the gain control element. The phone system requires a simple
full-wave averaging rectifier with good accuracy, since the rectifier
accuracy determines the (input) output level tracking accuracy. The
gain cell determines the distortion and noise characteristics, and the
phone system specifications here are very loose. These specs could
have been met with a simple operational transconductance
multiplier, or OTA, but the gain of an OTA is proportional to
temperature and this is very undesirable. Therefore, a linearized
transconductance multiplier was designed which is insensitive to
temperature and offers low noise and low distortion performance.
These features make the circuit useful in audio and data systems as
well as in telecommunications systems.
BASIC CIRCUIT HOOK-UP AND OPERATION
Figure 6 shows the block diagram of one half of the chip, (there are
two identical channels on the IC). The full-wave averaging rectifier
provides a gain control current, I
G
, for the variable gain (
G) cell.
The output of the
G cell is a current which is fed to the summing
node of the operational amplifier. Resistors are provided to establish
circuit gain and set the output DC bias.
INPUT
LEVEL
+20
C
E
OUTPUT
LEVEL
–20
NOISE
0dB
–40
–80
0dB
–40
–80
SR00679
Figure 5. Restricted Dynamic Range Channel
The circuit is intended for use in single power supply systems, so
the internal summing nodes must be biased at some voltage above
ground. An internal band gap voltage reference provides a very
stable, low noise 1.8V reference denoted V
REF
. The non-inverting
input of the op amp is tied to V
REF
, and the summing nodes of the
rectifier and
G cell (located at the right of R
1
and R
2
) have the
same potential. The THD trim pin is also at the V
REF
potential.
Figure 7 shows how the circuit is hooked up to realize an expandor.
The input signal, V
IN
, is applied to the inputs of both the rectifier and
the
G cell. When the input signal drops by 6dB, the gain control
current will drop by a factor of 2, and so the gain will drop 6dB. The
output level at V
OUT
will thus drop 12dB, giving us the desired 2-to-1
expansion.
Figure 8 shows the hook-up for a compressor. This is essentially an
expandor placed in the feedback loop of the op amp. The
G cell is
setup to provide AC feedback only, so a separate DC feedback loop
is provided by the two R
DC
and C
DC
. The values of R
DC
will
determine the DC bias at the output of the op amp. The output will
bias to:
R
DC1
R
DC2
R
4
V
OUT
DC
1
V
CC
PIN 13
GND PIN 4
OUTPUT
7,10
V
REF
1.8V
R
4
30k
1,16
C
RECT
R
1
10k
2,15
RECT
IN
G
IN
3,14
20k
R
2
20k
R
3
6,11
5,12
INV
IN
R
3
THD TRIM
8,9
IG
G
SR00680
Figure 6. Chip Block Diagram (1 of 2 Channels)
–
+
V
IN
V
OUT
V
REF
G
*C
IN1
*C
IN2
*C
RECT
R
3
R
4
R
1
R
2
GAIN
2 R3VIN(avg)
R1R2IB
NOTE:
I
B
= 140
μ
A
*EXTERNAL COMPONENTS
SR00681
Figure 7. Basic Expander
V
REF
1
R
DCTOT
30k
1.8V
The output of the expander will bias up to:
R
3
R
4
V
OUT
DC
1
V
REF
V
REF
1
20k
30k
1.8V
3.0V
The output will bias to 3.0V when the internal resistors are used.
External resistors may be placed in series with R
3
, (which will affect
the gain), or in parallel with R
4
to raise the DC bias to any desired
value.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SA571N | Compandor |
| SA57254-XX | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
| SA57254-28GW | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
| SA57254-30GW | Ceramic Multilayer Capacitor; Capacitance:47pF; Capacitance Tolerance:+/- 5 %; Working Voltage, DC:100V; Dielectric Characteristic:C0G/NP0; Package/Case:0603; Series:VJ; Leaded Process Compatible:Yes; Mounting Type:Surface Mount |
| SA57254-33GW | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SA571DG | 功能描述:音頻放大器 Dual Gain Compandor Industrial Temp RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| SA571DG | 制造商:ON Semiconductor 功能描述:Standard Recovery Rectifier |
| SA571DR2 | 功能描述:音頻放大器 Dual Gain Compandor RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| SA571DR2G | 功能描述:音頻放大器 Dual Gain Compandor Industrial Temp RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| SA571E-2200 | 制造商:Elan 功能描述:TOUCH PAD |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。