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參數(shù)資料
| 型號(hào)： | AD9744ARZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 6/32頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC DAC 14BIT 210MSPS 28-SOIC |
| 產(chǎn)品培訓(xùn)模塊： | Data Converter Fundamentals DAC Architectures |
| 標(biāo)準(zhǔn)包裝： | 27 |
| 系列： | TxDAC® |
| 設(shè)置時(shí)間： | 11ns |
| 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： | 模擬和數(shù)字 |
| 功率耗散（最大）： | 145mW |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 28-SOIC（0.295"，7.50mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 28-SOIC W |
| 包裝： | 管件 |
| 輸出數(shù)目和類型： | 2 電流，單極；2 電流，雙極 |
| 采樣率（每秒）： | 210M |
| 產(chǎn)品目錄頁面： | 785 (CN2011-ZH PDF) |
| 配用： | AD9744ACP-PCBZ-ND - BOARD EVAL FOR AD9744ACP |
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AD9744
Data Sheet
Rev. C | Page 14 of 32
The control amplifier allows a wide (10:1) adjustment span of
IOUTFS over a 2 mA to 20 mA range by setting IREF between 62.5 A
and 625 A. The wide adjustment span of IOUTFS provides several
benefits. The first relates directly to the power dissipation of the
Dissipation section). The second 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 500 kHz and can be used for low frequency small
signal multiplying applications.
DAC TRANSFER FUNCTION
Both DACs in the AD9744 provide complementary current
outputs, IOUTA and IOUTB. IOUTA provides a near full-scale
current output, IOUTFS, when all bits are high (that is, DAC
CODE = 16383), while IOUTB, the complementary output,
provides no current. The current output appearing at IOUTA
and IOUTB is a function of both the input code and IOUTFS and
can be expressed as
(
)
OUTFS
I
CODE
DAC
IOUTA
×
=
16384
/
(1)
(
)
OUTFS
I
CODE
DAC
IOUTB
×
=
/16384
16383
(2)
where DAC CODE = 0 to 16383 (that is, decimal representation).
As mentioned previously, IOUTFS is a function of the reference
current IREF, which is nominally set by a reference voltage,
VREFIO, and external resistor, RSET. It can be expressed as
REF
OUTFS
I
×
= 32
(3)
where
SET
REFIO
REF
R
V
I
/
=
(4)
The two current outputs will typically drive a resistive load
directly or via a transformer. If dc coupling is required, IOUTA
and IOUTB should be directly connected to matching resistive
loads, RLOAD, that are tied to analog common, ACOM. Note that
RLOAD may represent the equivalent load resistance seen by
IOUTA or IOUTB as would be the case in a doubly terminated
50 or 75 cable. The single-ended voltage output appearing
at the IOUTA and IOUTB nodes is simply
LOAD
OUTA
R
IOUTA
V
×
=
(5)
LOAD
OUTB
R
IOUTB
V
×
=
(6)
Note that the full-scale value of VOUTA and VOUTB should not
exceed the specified output compliance range to maintain
specified distortion and linearity performance.
(
)
LOAD
DIFF
R
IOUTB
IOUTA
V
×
=
(7)
Substituting the values of IOUTA, IOUTB, IREF, and VDIFF can be
expressed as
(
)
[
]
(
)
REFIO
SET
LOAD
DIFF
V
R
CODE
DAC
V
×
×
=
/
16384
/
16383
32
2
(8)
Equation 7 and Equation 8 highlight some of the advantages of
operating the AD9744 differentially. First, the differential operation
helps cancel common-mode error sources associated with IOUTA
and IOUTB, such as noise, distortion, and dc offsets. Second, the
differential code dependent current and subsequent voltage, VDIFF,
is twice the value of the single-ended voltage output (that is, VOUTA
or VOUTB), 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 (VDIFF) of the
AD9744 can be enhanced by selecting temperature tracking
resistors for RLOAD and RSET due to their ratiometric relationship,
as shown in Equation 8.
ANALOG OUTPUTS
The complementary current outputs in each DAC, IOUTA, and
IOUTB may be configured for single-ended or differential oper-
ation. IOUTA and IOUTB can be converted into complementary
single-ended voltage outputs, VOUTA and VOUTB, via a load resistor,
Equation 5 through Equation 8. The differential voltage, VDIFF,
existing between VOUTA and VOUTB, can also be converted to a
single-ended voltage via a transformer or differential amplifier
configuration. The ac performance of the AD9744 is optimum
and specified using a differential transformer-coupled output in
which the voltage swing at IOUTA and IOUTB is limited to ±0.5 V.
The distortion and noise performance of the AD9744 can be
enhanced when it is configured for differential operation. The
common-mode error sources of both IOUTA and IOUTB can
be significantly reduced by the common-mode rejection of a
transformer or differential amplifier. These common-mode
error sources include even-order distortion products and noise.
The enhancement in distortion performance becomes more
significant as the frequency content of the reconstructed
waveform increases and/or its amplitude decreases. This is due
to the first-order cancellation of various dynamic common-
mode distortion mechanisms, digital feedthrough, and noise.
Performing a differential-to-single-ended conversion via a
transformer also provides the ability to deliver twice the
reconstructed signal power to the load (assuming no source
termination). Since the output currents of IOUTA and IOUTB
are complementary, they become additive when processed
differentially. A properly selected transformer will allow the
AD9744 to provide the required power and voltage levels to
different loads.
The output impedance of IOUTA and IOUTB is determined by
the equivalent parallel combination of the PMOS switches
associated with the current sources and is typically 100 k in
parallel with 5 pF. It is also slightly dependent on the output
voltage (that is, VOUTA and VOUTB) due to the nature of a PMOS
device. As a result, maintaining IOUTA and/or IOUTB at a
virtual ground via an I-V op amp configuration will result in
the optimum dc linearity. Note that the INL/DNL specifications
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD9744ARZ1 | 制造商:AD 制造商全稱:Analog Devices 功能描述:14-Bit, 210 MSPS TxDAC㈢ D/A Converter |
| AD9744ARZRL | 功能描述:IC DAC 14BIT 210MSPS 28-SOIC RoHS:是 類別: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)目和類型:1 電流，單極；1 電流，雙極 采樣率（每秒）:* |
| AD9744ARZRL1 | 制造商:AD 制造商全稱:Analog Devices 功能描述:14-Bit, 210 MSPS TxDAC㈢ D/A Converter |
| AD9744-EB | 制造商:Analog Devices 功能描述:AD9744 EVALUATION BOARD (AD9744-EB) - Bulk |
| AD9745 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Dual 8-/10-/12-/14-/16-Bit 250 MSPS Digital-to-Analog Converters |
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