参数资料
| 型号： | AD603AQ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 5/25页 |
| 文件大小： | 0K |
| 描述： | IC AMP VGA 90MHZ LN 50MA 8CDIP |
| 标准包装： | 48 |
| 系列： | X-AMP® |
| 放大器类型： | 可变增益 |
| 电路数： | 1 |
| 转换速率： | 275 V/µs |
| -3db带宽： | 90MHz |
| 电流 - 输入偏压： | 200nA |
| 电流 - 电源： | 12.5mA |
| 电流 - 输出 / 通道： | 50mA |
| 电压 - 电源，单路/双路(±)： | 9.5 V ~ 12.6 V，±4.75 V ~ 6.3 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 通孔 |
| 封装/外壳： | 8-CDIP（0.300"，7.62mm） |
| 供应商设备封装： | 8-CERDIP |
| 包装： | 管件 |
| 产品目录页面： | 774 (CN2011-ZH PDF) |
| 配用： | AD603-EVALZ-ND - BOARD EVALUATION FOR AD603 |
AD603
Data Sheet
Rev. K | Page 12 of 24
THEORY OF OPERATION
The AD603 comprises a fixed-gain amplifier, preceded by a
broadband passive attenuator of 0 dB to 42.14 dB, having a gain
control scaling factor of 40 dB per volt. The fixed gain is laser-
trimmed in two ranges, to either 31.07 dB (×35.8) or 50 dB
(×358), or it may be set to any range in between using one
external resistor between Pin 5 and Pin 7. Somewhat higher
gain can be obtained by connecting the resistor from Pin 5 to
common, but the increase in output offset voltage limits the
maximum gain to about 60 dB. For any given range, the
bandwidth is independent of the voltage-controlled gain. This
system provides an underrange and overrange of 1.07 dB in all
cases; for example, the overall gain is 11.07 dB to +31.07 dB in
the maximum bandwidth mode (Pin 5 and Pin 7 strapped).
This X-AMP structure has many advantages over former
methods of gain control based on nonlinear elements. Most
importantly, the fixed-gain amplifier can use negative feedback
to increase its accuracy. Because large inputs are first attenuated,
the amplifier input is always small. For example, to deliver a
±1 V output in the 1 dB/+41 dB mode (that is, using a fixed
amplifier gain of 41.07 dB), its input is only 8.84 mV; therefore,
the distortion can be very low. Equally important, the small-
signal gain and phase response, and thus the pulse response, are
essentially independent of gain.
Figure 31 is a simplified schematic. The input attenuator is a
7-section R-2R ladder network, using untrimmed resistors of
nominally R = 62.5 , which results in a characteristic resistance of
125 ± 20%. A shunt resistor is included at the input and laser
trimmed to establish a more exact input resistance of 100 ± 3%,
which ensures accurate operation (gain and HP corner frequency)
when used in conjunction with external resistors or capacitors.
The nominal maximum signal at input VINP is 1 V rms
(±1.4 V peak) when using the recommended ±5 V supplies,
although operation to ±2 V peak is permissible with some
increase in HF distortion and feedthrough. Pin 4 (COMM)
must be connected directly to the input ground; significant
impedance in this connection reduces the gain accuracy.
The signal applied at the input of the ladder network is attenuated
by 6.02 dB by each section; therefore, the attenuation to each of
the taps is progressively 0 dB, 6.02 dB, 12.04 dB, 18.06 dB,
24.08 dB, 30.1 dB, 36.12 dB, and 42.14 dB. A unique circuit
technique is employed to interpolate between these tap points,
indicated by the slider in Figure 31, thus providing continuous
attenuation from 0 dB to 42.14 dB. It helps in understanding the
AD603 to think in terms of a mechanical means for moving this
slider from left to right; in fact, its position is controlled by the
voltage between Pin 1 and Pin 2. The details of the gain control
interface are in the The Gain Control Interface section.
The gain is at all times very exactly determined, and a linear-in-
dB relationship is automatically guaranteed by the exponential
nature of the attenuation in the ladder network (the X-AMP
principle). In practice, the gain deviates slightly from the ideal
law, by about ±0.2 dB peak (see, for example, Figure 5).
NOISE PERFORMANCE
An important advantage of the X-AMP is its superior noise
performance. The nominal resistance seen at inner tap points is
41.7 (one third of 125 ), which exhibits a Johnson noise
spectral density (NSD) of 0.83 nV/√Hz (that is, √4kTR) at 27°C,
which is a large fraction of the total input noise. The first stage
of the amplifier contributes a further 1 nV/√Hz, for a total input
noise of 1.3 nV/√Hz. It is apparent that it is essential to use a
low resistance in the ladder network to achieve the very low
specified noise level. The source impedance of the signal
forms a voltage divider with the 100 input resistance of the
AD603. In some applications, the resulting attenuation may
be unacceptable, requiring the use of an external buffer or
preamplifier to match a high impedance source to the low
impedance AD603.
The noise at maximum gain (that is, at the 0 dB tap) depends on
whether the input is short-circuited or open-circuited. When
short-circuited, the minimum NSD of slightly over 1 nV/√Hz is
achieved. When open-circuited, the resistance of 100 looking
into the first tap generates 1.29 nV/√Hz, so the noise increases
to 1.63 nV/√Hz. (This last calculation would be important if the
AD603 were preceded by, for example, a 900 resistor to allow
operation from inputs up to 10 V rms.) As the selected tap
moves away from the input, the dependence of the noise on
source impedance quickly diminishes.
Apart from the small variations just discussed, the signal-to-
noise (SNR) at the output is essentially independent of the
attenuator setting. For example, on the 11 dB/+31 dB range,
the fixed gain of ×35.8 raises the output NSD to 46.5 nV/√Hz.
Therefore, for the maximum undistorted output of 1 V rms and
a 1 MHz bandwidth, the output SNR would be 86.6 dB, that is,
20 log(1 V/46.5 V).
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相关代理商/技术参数 |
参数描述 |
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| AD603AR | 功能描述:IC AMP VGA 90MHZ LN 50MA 8SOIC RoHS:否 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:X-AMP® 标准包装:2,500 系列:Excalibur™ 放大器类型:J-FET 电路数:1 输出类型:- 转换速率:45 V/µs 增益带宽积:10MHz -3db带宽:- 电流 - 输入偏压:20pA 电压 - 输入偏移:490µV 电流 - 电源:1.7mA 电流 - 输出 / 通道:48mA 电压 - 电源，单路/双路(±):4.5 V ~ 38 V，±2.25 V ~ 19 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-SOIC 包装:带卷 (TR) |
| AD603AR-REEL | 功能描述:IC AMP VGA 90MHZ LN 50MA 8SOIC RoHS:否 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:X-AMP® 标准包装:2,500 系列:Excalibur™ 放大器类型:J-FET 电路数:1 输出类型:- 转换速率:45 V/µs 增益带宽积:10MHz -3db带宽:- 电流 - 输入偏压:20pA 电压 - 输入偏移:490µV 电流 - 电源:1.7mA 电流 - 输出 / 通道:48mA 电压 - 电源，单路/双路(±):4.5 V ~ 38 V，±2.25 V ~ 19 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-SOIC 包装:带卷 (TR) |
| AD603AR-REEL7 | 功能描述:IC AMP VGA 90MHZ LN 50MA 8SOIC RoHS:否 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:X-AMP® 标准包装:2,500 系列:Excalibur™ 放大器类型:J-FET 电路数:1 输出类型:- 转换速率:45 V/µs 增益带宽积:10MHz -3db带宽:- 电流 - 输入偏压:20pA 电压 - 输入偏移:490µV 电流 - 电源:1.7mA 电流 - 输出 / 通道:48mA 电压 - 电源，单路/双路(±):4.5 V ~ 38 V，±2.25 V ~ 19 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-SOIC 包装:带卷 (TR) |
| AD603ARZ | 功能描述:IC AMP VGA 90MHZ LN 50MA 8SOIC RoHS:是 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:X-AMP® 标准包装:2,500 系列:- 放大器类型:通用 电路数:4 输出类型:- 转换速率:0.6 V/µs 增益带宽积:1MHz -3db带宽:- 电流 - 输入偏压:45nA 电压 - 输入偏移:2000µV 电流 - 电源:1.4mA 电流 - 输出 / 通道:40mA 电压 - 电源，单路/双路(±):3 V ~ 32 V，±1.5 V ~ 16 V 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:14-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:14-TSSOP 包装:带卷 (TR) 其它名称:LM324ADTBR2G-NDLM324ADTBR2GOSTR |
| AD603ARZ | 制造商:Analog Devices 功能描述:Programmable Gain Amplifier IC |
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