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參數(shù)資料
| 型號： | AD9754-EB |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | 14-Bit, 125 MSPS High Performance TxDAC D/A Converter |
| 中文描述： | 14位，125 MSPS的TxDAC系列高性能D / A轉(zhuǎn)換 |
| 文件頁數(shù)： | 10/24頁 |
| 文件大?。?/td> | 327K |
| 代理商： | AD9754-EB |
AD9754
–10–
REV. A
These last two equations highlight some of the advantages of
operating the AD9754 differentially. First, the differential op-
eration will help cancel common-mode error sources associated
with IOUTA and IOUTB such as noise, distortion and dc off-
sets. Second, the differential code-dependent current and
subsequent voltage, V
DIFF
, is twice the value of the single-
ended voltage output (i.e., V
OUTA
or V
OUTB
), thus providing
twice the signal power to the load.
Note that the gain drift temperature performance for a single-
ended (VOUTA and VOUTB) or differential output (V
DIFF
) of
the AD9754 can be enhanced by selecting temperature tracking
resistors for R
LOAD
and R
SET
due to their ratiometric relation-
ship as shown in Equation 8.
REFERENCE OPERATION
The AD9754 contains an internal 1.20 V bandgap reference
that can be easily disabled and overridden by an external
reference. REFIO serves as either an
input
or
output,
depending
on whether the internal or external reference is selected. If
REFLO is tied to ACOM, as shown in Figure 17, the internal
reference is activated, and REFIO provides a 1.20V output. In
this case, the internal reference
must
be compensated externally
with a ceramic chip capacitor of 0.1
μ
F or greater from REFIO
to REFLO. Also, REFIO should be buffered with an external
amplifier having an input bias current less than 100nA if any
additional loading is required.
150pF
+1.2V REF
AVDD
REFLO
CURRENT
SOURCE
ARRAY
+5V
REFIO
FS ADJ
2k
V
0.1
m
F
AD9754
ADDITIONAL
LOAD
OPTIONAL
EXTERNAL
REF BUFFER
Figure 17. Internal Reference Configuration
The internal reference can be disabled by connecting REFLO to
AVDD. In this case, an external reference may then be applied
to REFIO as shown in Figure 18. The external reference may
provide either a fixed reference voltage to enhance accuracy and
drift performance or a varying reference voltage for gain control.
Note that the 0.1
μ
F compensation capacitor is not required
since the internal reference is disabled, and the high input im-
pedance (i.e., 1 M
) of REFIO minimizes any loading of the
external reference.
REFERENCE CONTROL AMPLIFIER
The AD9754 also contains an internal control amplifier that is
used to regulate the DAC’s full-scale output current, I
OUTFS
.
The control amplifier is configured as a V-I converter, as shown
in Figure 18, such that its current output, I
REF
, is determined by
150pF
+1.2V REF
AVDD
REFLO
CURRENT
SOURCE
ARRAY
AVDD
REFIO
FS ADJ
R
SET
AD9754
EXTERNAL
REF
I
REF
=
V
REFIO
/R
SET
AVDD
REFERENCE
CONTROL
AMPLIFIER
V
REFIO
Figure 18. External Reference Configuration
the ratio of the V
REFIO
and an external resistor, R
SET
, as stated
in Equation 4. I
REF
is copied over to the segmented current
sources with the proper scaling factor to set I
OUTFS
as stated in
Equation 3.
The control amplifier allows a wide (10:1) adjustment span of
I
OUTFS
over a 2mA to 20 mA range by setting IREF between
62.5
μ
A and 625
μ
A. The wide adjustment span of I
OUTFS
provides several application benefits. The first benefit relates
directly to the power dissipation of the AD9754, which is pro-
portional to I
OUTFS
(refer to the Power Dissipation section). The
second benefit relates to the 20 dB adjustment, which is useful
for system gain control purposes.
The small signal bandwidth of the reference control amplifier
is approximately 0.5 MHz. The output of the control amplifier
is internally compensated via a 150 pF capacitor that limits the
control amplifier small-signal bandwidth and reduces its output
impedance. Since the –3 dB bandwidth corresponds to the
dominant pole, and hence the time constant, the settling time of
the control amplifier to a stepped reference input response can
be approximated In this case, the time constant can be approxi-
mated to be 320 ns.
There are two methods in which I
REF
can be varied for a fixed
R
SET
. The first method is suitable for a single-supply system in
which the internal reference is disabled, and the common-mode
voltage of REFIO is varied over its compliance range of 1.25 V
to 0.10 V. REFIO can be driven by a single-supply amplifier or
DAC, thus allowing I
REF
to be varied for a fixed R
SET
. Since the
1.2V
150pF
+1.2V REF
AVDD
REFLO
CURRENT
SOURCE
ARRAY
AVDD
REFIO
FS ADJ
R
SET
AD9754
I
REF
=
V
REF
/R
SET
AVDD
V
REF
V
DD
R
FB
OUT1
OUT2
AGND
DB7–DB0
AD7524
AD1580
0.1V TO 1.2V
Figure 19. Single-Supply Gain Control Circuit
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PDF描述 |
|---|---|
| AD9754AR | 14-Bit, 125 MSPS High Performance TxDAC D/A Converter |
| AD9760ARU50 | 10-Bit, 125 MSPS TxDAC D/A Converter |
| AD9760 | 10-Bit, 125 MSPS TxDAC D/A Converter |
| AD9760-EB | 10-Bit, 125 MSPS TxDAC D/A Converter |
| AD9760AR | 10-Bit, 125 MSPS TxDAC D/A Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD9754-EBZ | 功能描述:BOARD EVAL FOR AD9754 RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - 數(shù)模轉(zhuǎn)換器 (DAC) 系列:TxDAC® 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- DAC 的數(shù)量:4 位數(shù):12 采樣率（每秒）:- 數(shù)據(jù)接口:串行，SPI? 設(shè)置時間:3µs DAC 型:電流/電壓 工作溫度:-40°C ~ 85°C 已供物品:板 已用 IC / 零件:MAX5581 |
| AD9755 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:AD9755: 14-Bit. 300 MSPS High-Speed TxDAC+?D/A Converter Data Sheet (Rev. A. 1/03) |
| AD9755AST | 制造商:Analog Devices 功能描述:DAC 1-CH Segment 14-bit 48-Pin LQFP 制造商:Rochester Electronics LLC 功能描述:14-BIT, 300 MSPS TXDAC+ D/A CONVERTER - Bulk 制造商:Analog Devices 功能描述:CONVERTOR DA ((NW)) |
| AD9755-AST | 制造商:Analog Devices 功能描述: |
| AD9755ASTRL | 制造商:Analog Devices 功能描述:DAC 1-CH Segment 14-bit 48-Pin LQFP T/R 制造商:Rochester Electronics LLC 功能描述:14-BIT, 300 MSPS TXDAC+ D/A CONVERTER - Tape and Reel |
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