- 您现在的位置：买卖IC网 > PDF目录2063 > ADA4938-2ACPZ-RL (Analog Devices Inc)IC ADC DRIVER DUAL DIFF 24LFCSP PDF资料下载
参数资料
| 型号： | ADA4938-2ACPZ-RL |
| 厂商： | Analog Devices Inc |
| 文件页数： | 11/28页 |
| 文件大小： | 0K |
| 描述： | IC ADC DRIVER DUAL DIFF 24LFCSP |
| 标准包装： | 5,000 |
| 类型： | ADC 驱动器 |
| 应用： | 数据采集 |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-VFQFN 裸露焊盘，CSP |
| 供应商设备封装： | 24-LFCSP-VQ（4x4） |
| 包装： | 带卷 (TR) |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页当前第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页
ADA4938-1/ADA4938-2
Rev. A | Page 19 of 28
THEORY OF OPERATION
The ADA4938-x differs from conventional op amps in that it
has two outputs whose voltages move in opposite directions.
Like an op amp, it relies on open-loop gain and negative
feedback to force these outputs to the desired voltages. The
ADA4938-x behaves much like a standard voltage feedback op
amp and makes it easier to perform single-ended-to-differential
conversions, common-mode level shifting, and amplifications of
differential signals. Also like an op amp, the ADA4938-x has
high input impedance and low output impedance.
Two feedback loops are employed to control the differential and
common-mode output voltages. The differential feedback, set
with external resistors, controls only the differential output
voltage. The common-mode feedback controls only the common-
mode output voltage. This architecture makes it easy to set the
output common-mode level to any arbitrary value. It is forced,
by internal common-mode feedback, to be equal to the voltage
applied to the VOCM input, without affecting the differential
output voltage.
The ADA4938-x architecture results in outputs that are highly
balanced over a wide frequency range without requiring tightly
matched external components. The common-mode feedback
loop forces the signal component of the output common-
mode voltage to zero, which results in nearly perfectly balanced
differential outputs that are identical in amplitude and are
exactly 180° apart in phase.
ANALYZING AN APPLICATION CIRCUIT
The ADA4938-x uses open-loop gain and negative feedback to
force its differential and common-mode output voltages in such
a way as to minimize the differential and common-mode error
voltages. The differential error voltage is defined as the voltage
between the differential inputs labeled +IN and IN (see
Figure 57). For most purposes, this voltage can be assumed
to be zero. Similarly, the difference between the actual output
common-mode voltage and the voltage applied to VOCM can also
be assumed to be zero. Starting from these two assumptions,
any application circuit can be analyzed.
SETTING THE CLOSED-LOOP GAIN
The differential-mode gain of the circuit in Figure 57 can be
determined by
G
F
dm
IN
dm
OUT
R
V
=
,
This assumes the input resistors (RG) and feedback resistors (RF)
on each side are equal.
ESTIMATING THE OUTPUT NOISE VOLTAGE
The differential output noise of the ADA4938 can be estimated
using the noise model in Figure 58. The input-referred noise
voltage density, vnIN, is modeled as a differential input, and the
noise currents, inIN and inIN+, appear between each input and
ground. The noise currents are assumed to be equal and produce a
voltage across the parallel combination of the gain and feedback
resistances. vn, cm is the noise voltage density at the VOCM pin.
the input noise sources, the multiplication factors, and the output-
referred noise density terms.
ADA4938
+
RF2
VnOD
VnCM
VOCM
VnIN
RF1
RG2
RG1
VnRF1
VnRF2
VnRG1
VnRG2
inIN+
inIN–
06
59
2-
0
05
Figure 58. ADA4938 Noise Model
Table 9. Output Noise Voltage Density Calculations
Input Noise Contribution
Input Noise Term
Input Noise
Voltage Density
Output
Multiplication Factor
Output Noise
Voltage Density Term
Differential Input
vnIN
GN
vnO1 = GN(vnIN)
Inverting Input
inIN
inIN × (RG2||RF2)
GN
vnO2 = GN[inIN × (RG2||RF2)]
Noninverting Input
inIN+
inIN+ × (RG1||RF1)
GN
vnO3 = GN[inIN+ × (RG1||RF1)]
VOCM Input
vn, cm
GN(β1 β2)
vnO4 = GN(β1 β2)(vnCM)
Gain Resistor, RG1
vnRG1
(4kTRG1)1/2
GN(1 β1)
vnO5 = GN(1 β1)(4kTRG1)1/2
Gain Resistor, RG2
vnRG2
(4kTRG2)1/2
GN(1 β2)
vnO6 = GN(1 β2)(4kTRG2)1/2
Feedback Resistor, RF1
vnRF1
(4kTRF1)1/2
1
vnO7 = (4kTRF1)1/2
Feedback Resistor, RF2
vnRF2
(4kTRF2)1/2
1
vnO8 = (4kTRF2)1/2
相关PDF资料 |
PDF描述 |
|---|---|
| ADA4941-1YRZ-R7 | IC DIFF ADC DRIVER 18BIT 8SOIC |
| ADA4960-1ACPZ-R2 | IC ADC DRIVER DIFF 16LFCSP |
| ADATE205BSVZ | IC DCL DUAL 250MHZ ATE 100TQFP |
| ADATE206BSVZ | IC DCL DUAL 500MHZ ATE 100TQFP |
| ADAU1401AWBSTZ-RL | IC AUDIO PROC 28/56BIT 48LQFP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ADA4938-2YCP-EBZ | 功能描述:BOARD EVAL FOR ADA4938-2YCP RoHS:是 类别:编程器，开发系统 >> 评估板 - 运算放大器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- |
| ADA4939-1 | 制造商:AD 制造商全称:Analog Devices 功能描述:Ultralow Distortion Differential ADC Driver |
| ADA4939-1YCP-EBZ | 功能描述:BOARD EVAL FOR ADA4939-1YCP RoHS:是 类别:编程器，开发系统 >> 评估板 - 运算放大器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- |
| ADA4939-1YCPZ-R2 | 制造商:Analog Devices 功能描述:SP Amp Differential ADC Driver Single 5.25V 16-Pin LFCSP EP T/R 制造商:Analog Devices 功能描述:SP AMP DIFFERENTIAL ADC DRVR SGL 5.25V 16LFCSP EP - Tape and Reel 制造商:Analog Devices 功能描述:SP Amp Differential ADC Driver Single 5.25V 16-Pin LFCSP EP Tape & Reel |
| ADA4939-1YCPZ-R7 | 功能描述:IC AMP DIFF ULDIST LN 16LFCSP RoHS:是 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:50 系列:- 放大器类型:J-FET 电路数:2 输出类型:- 转换速率:13 V/µs 增益带宽积:3MHz -3db带宽:- 电流 - 输入偏压:65pA 电压 - 输入偏移:3000µV 电流 - 电源:1.4mA 电流 - 输出 / 通道:- 电压 - 电源，单路/双路(±):7 V ~ 36 V，±3.5 V ~ 18 V 工作温度:-40°C ~ 85°C 安装类型:通孔 封装/外壳:8-DIP（0.300"，7.62mm） 供应商设备封装:8-PDIP 包装:管件 |
发布紧急采购，3分钟左右您将得到回复。