参数资料
| 型号： | AD797AR |
| 厂商： | Analog Devices Inc |
| 文件页数： | 3/20页 |
| 文件大小： | 0K |
| 描述： | IC OPAMP GP 110MHZ ULDIST 8SOIC |
| 标准包装： | 98 |
| 放大器类型： | 通用 |
| 电路数： | 1 |
| 转换速率： | 20 V/µs |
| 增益带宽积： | 110MHz |
| -3db带宽： | 8MHz |
| 电流 - 输入偏压： | 250nA |
| 电压 - 输入偏移： | 25µV |
| 电流 - 电源： | 8.2mA |
| 电流 - 输出 / 通道： | 50mA |
| 电压 - 电源，单路/双路(±)： | ±5 V ~ 15 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SO |
| 包装： | 管件 |
Data Sheet
AD797
Rev. J | Page 11 of 20
THEORY OF OPERATION
The architecture of the AD797 was developed to overcome
inherent limitations in previous amplifier designs. Previous
precision amplifiers used three stages to ensure high open-loop
gain (see Figure 31) at the expense of additional frequency com-
pensation components. Slew rate and settling performance are
usually compromised, and dynamic performance is not adequate
beyond audio frequencies. As can be seen in Figure 31, the first
stage gain is rolled off at high frequencies by the compensation
network. Second stage noise and distortion then appears at the
input and degrade performance. The AD797, on the other hand,
uses a single ultrahigh gain stage to achieve dc as well as dynamic
precision. As shown in the simplified schematic (Figure 32),
Node A, Node B, and Node C track the input voltage, forcing
the operating points of all pairs of devices in the signal path to
match. By exploiting the inherent matching of devices fabricated on
the same IC chip, high open-loop gain, CMRR, PSRR, and low
VOS are guaranteed by pairwise device matching (that is, NPN
to NPN and PNP to PNP), not by an absolute parameter such as
beta and the early voltage.
R1
C1
gm
GAIN = gm × R1 × 5 × 106
GAIN = gm × R1 × A2 × A3
C1
R2
BUFFER
RL
VOUT
a.
b.
A2
A3
C2
00846-
030
Figure 31. Model of AD797 vs. That of a Typical Three-Stage Amplifier
R2
R1
I5
VOUT
Q1
Q2
+IN
–IN
R3
Q5
C
Q6
I7
I1
I4
I6
Q12
Q8
Q9
Q11
Q10
Q3
Q7
Q4
A
B
CN
CC
VSS
VCC
00846-
031
Figure 32. AD797 Simplified Schematic
This matching benefits not just dc precision, but, because it holds
up dynamically, both distortion and settling time are also reduced.
This single stage has a voltage gain of >5 × 106 and VOS < 80 μV,
while at the same time providing a THD + noise of less than
120 dB and true 16-bit settling in less than 800 ns.
The elimination of second-stage noise effects has the additional
benefit of making the low noise of the AD797 (<0.9 nV/√Hz)
extend to beyond 1 MHz. This means new levels of perform-
ance for sampled data and imaging systems. All of this
performance as well as load drive in excess of 30 mA are made
possible by the Analog Devices, Inc., advanced complementary
bipolar (CB) process.
Another unique feature of this circuit is that the addition of a
distortion due to the output stage. This can best be explained by
referring to a simplified representation of the AD797 using
idealized blocks for the different circuit elements (Figure 33).
A single equation yields the open-loop transfer function of this
amplifier; solving it at Node B yields
ω
ω
ω
=
j
A
C
j
C
j
A
C
g
V
C
N
m
IN
OUT
where:
gm is the transconductance of Q1 and Q2.
A is the gain of the output stage (~1).
VOUT is voltage at the output.
VIN is differential input voltage.
When CN is equal to CC, the ideal single-pole op amp response
is attained:
C
j
g
V
m
IN
OUT
ω
=
In Figure 33, the terms of Node A, which include the properties of
the output stage, such as output impedance and distortion, cancel
by simple subtraction. Therefore, the distortion cancellation does
not affect the stability or frequency response of the amplifier. With
only 500 μA of output stage bias, the AD797 delivers a 1 kHz
sine wave into 60 Ω at 7 V rms with only 1 ppm of distortion.
–IN
+IN
Q1
Q2
I1
I2
VOUT
I3
C
A
I4
CN
CC
B
00846-
032
CURRENT
MIRROR
A
1
Figure 33. AD797 Block Diagram
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相关代理商/技术参数 |
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|---|---|
| AD797AR-REEL | 功能描述:IC OPAMP GP 110MHZ ULDIST 8SOIC RoHS:否 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:150 系列:- 放大器类型:音频 电路数:2 输出类型:- 转换速率:5 V/µs 增益带宽积:12MHz -3db带宽:- 电流 - 输入偏压:100nA 电压 - 输入偏移:500µV 电流 - 电源:6mA 电流 - 输出 / 通道:50mA 电压 - 电源，单路/双路(±):4 V ~ 32 V，±2 V ~ 16 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:8-TSSOP 包装:管件 |
| AD797AR-REEL7 | 功能描述:IC OPAMP GP 110MHZ ULDIST 8SOIC RoHS:否 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:150 系列:- 放大器类型:音频 电路数:2 输出类型:- 转换速率:5 V/µs 增益带宽积:12MHz -3db带宽:- 电流 - 输入偏压:100nA 电压 - 输入偏移:500µV 电流 - 电源:6mA 电流 - 输出 / 通道:50mA 电压 - 电源，单路/双路(±):4 V ~ 32 V，±2 V ~ 16 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:8-TSSOP 包装:管件 |
| AD797ARZ | 功能描述:IC OPAMP GP 110MHZ ULDIST 8SOIC RoHS:是 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:1 系列:MicroAmplifier™ 放大器类型:通用 电路数:4 输出类型:- 转换速率:3.5 V/µs 增益带宽积:1MHz -3db带宽:- 电流 - 输入偏压:5pA 电压 - 输入偏移:1500µV 电流 - 电源:220µA 电流 - 输出 / 通道:60mA 电压 - 电源，单路/双路(±):4.5 V ~ 36 V，±2.25 V ~ 18 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-SOIC（0.154"，3.90mm 宽） 供应商设备封装:14-SOIC 包装:剪切带 (CT) 其它名称:296-29363-1 |
| AD797ARZ-REEL | 功能描述:IC OPAMP GP 110MHZ ULDIST 8SOIC 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 |
| AD797ARZ-REEL7 | 功能描述:IC OPAMP GP 110MHZ ULDIST 8SOIC RoHS:是 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:150 系列:- 放大器类型:音频 电路数:2 输出类型:- 转换速率:5 V/µs 增益带宽积:12MHz -3db带宽:- 电流 - 输入偏压:100nA 电压 - 输入偏移:500µV 电流 - 电源:6mA 电流 - 输出 / 通道:50mA 电压 - 电源，单路/双路(±):4 V ~ 32 V，±2 V ~ 16 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:8-TSSOP 包装:管件 |
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