參數(shù)資料
型號(hào): AD9761-EB
廠(chǎng)商: Analog Devices, Inc.
英文描述: Dual 10-Bit TxDAC+⑩ with 2x Interpolation Filters
中文描述: 雙10位TxDAC系列⑩2倍內(nèi)插濾波器
文件頁(yè)數(shù): 15/23頁(yè)
文件大?。?/td> 246K
代理商: AD9761-EB
AD9761
–15–
REV. A
5 MSPS
RATIO – f
OUT
/f
CLK
40
30
0.05
0.15
40 MSPS
20
0
0.1
20 MSPS
10 MSPS
10
0
I
D
0.2
2.5 MSPS
5
35
25
15
Figure 34. I
DVDD
vs. Ratio @ DVDD = 3 V
APPLYING THE AD9761
OUTPUT CONFIGURATIONS
The following sections illustrate some typical output configura-
tions for the AD9761. Unless otherwise noted, it is assumed
that I
OUTFS
is set to a nominal 10 mA. For applications requir-
ing the optimum dynamic performance, a differential output
configuration is suggested. A differential output configuration
may consist of either an RF transformer or a differential op amp
configuration. The transformer configuration provides the opti-
mum high frequency performance and is recommended for any
application allowing for ac coupling. The differential op amp
configuration is suitable for applications requiring dc coupling, a
bipolar output, signal gain, and/or level shifting.
A single-ended output is suitable for applications requiring a
unipolar voltage output. A positive unipolar output voltage will
result if IOUTA and/or IOUTB is connected to an appropri-
ately sized load resistor, R
LOAD
, referred to ACOM. This
configuration may be more suitable for a single-supply system
requiring a dc coupled, ground referred output voltage. Alterna-
tively, an amplifier could be configured as an I-V converter thus
converting I
OUTA
or I
OUTB
into a negative unipolar voltage. This
configuration provides the best dc linearity since IOUTA or
IOUTB is maintained at a virtual ground.
DIFFERENTIAL COUPLING USING A TRANSFORMER
An RF transformer can be used to perform a differential-to-
single-ended signal conversion as shown in Figure 35. A differen-
tially coupled transformer output provides the optimum distortion
performance for output signals whose spectral content lies within
the transformers passband. An RF transformer such as the Mini
Circuits T1-1T provides excellent rejection of common-mode
distortion (i.e., even-order harmonics) and noise over a wide
frequency range. It also provides electrical isolation and the
ability to deliver twice the power to the load. Transformers with
different impedance ratios may also be used for impedance
matching purposes. Note that the transformer provides ac cou-
pling only.
OPTIONAL
R
DIFF
R
LOAD
MINI-CIRCUITS
T1-1T
IOUTA
IOUTB
AD9761
Figure 35. Differential Output Using a Transformer
The center-tap on the primary side of the transformer must be
connected to ACOM to provide the necessary dc current path
for both I
OUTA
and I
OUTB
. The complementary voltages appear-
ing at IOUTA and IOUTB (i.e., V
OUTA
and V
OUTB
) swing sym-
metrically around ACOM and should be maintained with the
specified output compliance range of the AD9761. A differential
resistor, R
DIFF
, may be inserted in applications in which the
output of the transformer is connected to the load, R
LOAD
, via a
passive reconstruction filter or cable requiring double termina-
tion. R
DIFF
is determined by the transformer’s impedance ratio
and provides the proper source termination which results in a
low VSWR. Note that approximately half the signal power will
be dissipated across R
DIFF
.
DIFFERENTIAL USING AN OP AMP
An op amp can also be used to perform a differential to single-
ended conversion as shown in Figure 36. The AD9761 is config-
ured with two equal load resistors, R
LOAD
, of 50
. The differential
voltage developed across IOUTA and IOUTB is converted to a
single-ended signal via the differential op amp configuration. An
optional capacitor can be installed across IOUTA and IOUTB
forming a real pole in a low-pass filter. The addition of this
capacitor also enhances the op amps distortion performance by
preventing the DACs high slewing output from overloading the
op amp’s input.
C
OPT
200
V
500
V
IOUTA
IOUTB
AD9761
R
LOAD
V
200
V
AD8042
500
V
R
LOAD
50
V
Figure 36. DC Differential Coupling Using an Op Amp
The common-mode rejection of this configuration is typically
determined by the resistor matching. In this circuit, the differen-
tial op amp circuit using the AD8042 is configured to provide
some additional signal gain. The op amp must operate from a
dual supply since its output is approximately
±
1.0 V. A high
speed amplifier capable of preserving the differential performance
of the AD9761 while meeting other system level objectives (i.e.,
cost, power) should be selected. The op amps differential gain, its
gain setting resistor values, and full-scale output swing capabili-
ties should all be considered when optimizing this circuit.
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AD9762AR 功能描述:IC DAC 12BIT 125MSPS 28-SOIC RoHS:否 類(lèi)別:集成電路 (IC) >> 數(shù)據(jù)采集 - 數(shù)模轉(zhuǎn)換器 系列:TxDAC® 產(chǎn)品培訓(xùn)模塊:Data Converter Fundamentals DAC Architectures 標(biāo)準(zhǔn)包裝:750 系列:- 設(shè)置時(shí)間:7µs 位數(shù):16 數(shù)據(jù)接口:并聯(lián) 轉(zhuǎn)換器數(shù)目:1 電壓電源:雙 ± 功率耗散(最大):100mW 工作溫度:0°C ~ 70°C 安裝類(lèi)型:表面貼裝 封裝/外殼:28-LCC(J 形引線(xiàn)) 供應(yīng)商設(shè)備封裝:28-PLCC(11.51x11.51) 包裝:帶卷 (TR) 輸出數(shù)目和類(lèi)型:1 電壓,單極;1 電壓,雙極 采樣率(每秒):143k
AD9762ARRL 功能描述:IC DAC 12BIT 100KSPS 28-SOIC RoHS:否 類(lèi)別:集成電路 (IC) >> 數(shù)據(jù)采集 - 數(shù)模轉(zhuǎn)換器 系列:TxDAC® 標(biāo)準(zhǔn)包裝:47 系列:- 設(shè)置時(shí)間:2µs 位數(shù):14 數(shù)據(jù)接口:并聯(lián) 轉(zhuǎn)換器數(shù)目:1 電壓電源:單電源 功率耗散(最大):55µW 工作溫度:-40°C ~ 85°C 安裝類(lèi)型:表面貼裝 封裝/外殼:28-SSOP(0.209",5.30mm 寬) 供應(yīng)商設(shè)備封裝:28-SSOP 包裝:管件 輸出數(shù)目和類(lèi)型:1 電流,單極;1 電流,雙極 采樣率(每秒):*