A10模块是EM公司为了进行高灵敏度测量和数据采集而推出的低噪声放大器模块，可以测量低于1nV的信号。对于要求高电压灵敏度以测量低噪声、低阻抗源的精密电压测量系统，A10是非常理想的输入单元。A10输入噪声与20Ω电阻所产生的热噪声一致。A10输入电压具有很高的稳定性，温度漂移约为1nV/℃。输入端为纯铜制成。输入阻抗由环路增益决定，且与时间相关。
A10直流增益超过5到10的12次方，也即意味着通过反馈电阻的控制可以获得很高的闭环增益，因而保证了良好的线性度。尽管开环增益极高，在100%反馈时A10依然稳定。这允许在反馈电阻两端并联一个滤波电容以控制稳定时间和来自测量电路的噪声。环路增益随频率增大而降低，从直流时的5e12以30dB/十倍频的斜率下降至20kHz时的单位1。这决定了放大器的响应时间，响应时间与设置的增益相关。
A10可以从输出端获得2mA的电流，因此在所设置的增益不低于1500时，增益将决定输出信号量级。较小的反馈电阻位于内部，为1Ω，因而若通过连接输出端和反馈点的方式将增益设置为单位1，那么最大输出电压为2mV。内部反馈电阻之所以取值这么小，原因在于该电阻所产生的热噪声与输入噪声串联，更高的电阻将明显增加A10的噪声。
由于A10功耗极低，非常适合使用电池供电的应用场景。推荐供电电压为±6V，静态供电电流仅为1.5mA。如果不使用电池供电，应注意选择供电电源类型，确保A10的噪声不因共模噪声而有所降低。尽管A10有很高的共模抑制比，但在纳伏量级测量时也应对此非常注意。
如果有需求的话，A10可以直接安装在印制电路板上，也可以使用高磁导率制成金属壳体来进行电磁屏蔽。偏置电压和偏置电流可以使用绝缘螺丝刀通过正面的两个小孔进行调节。
The EM A10 is a low level amplifier module for sensitive measurements, data collection and systems, where signals below 1 nanovolt may be measured. It is ideal for the input unit for precision voltage measuring systems, requiring voltage sensitivity for measuring low noise and low impedance sources. The noise level of the A10 is equivalent to a perfect resistor of about 20 ohms. When used with a digital voltmeter, steady one nanovolt digits may be displayed, with a response time constant of less than a second. The input voltage stability of the A10 is very high, with the drift around a nanovolt per degree C. The input connectors are made from pure copper. The input impedance is very high, and is time dependent, determined by the loop gain.
The very high D.C. gain of greater than five by ten to the power twelve means that high overall gain may be used, controlled precisely by feedback resistors, thus ensuring a good degree of linearity with the accuracy defined by the feedback resistors used. Despite the gain, the A10 is stable with 100% feedback. This allows a filter capacitor to be used across the feedback resistor to control the rise time and noise from the measurement circuit. The loop gain is reduced from the DC figure of 5e12 at the rate of 30 dB per frequency decade to unity at 20KHz. This determines the response time of the amplifier, which will vary according to the set gain.
The A10 can deliver 2 milliamps of current from its output and so the set gain will determine the level of output signal at low values of gain less than 1,500.
The internal 'low' feedback resistor is 1 ohm, and so if a gain of unity is set by connecting the output to the feedback terminal directly, the maximum output voltage will be 2 millivolts. The internal feedback resistor needs to be this low, because the noise generated by this resistor is in series with the input noise, and any higher resistance would cause a significant increase in the total A10 noise.
The power consumption is very low, making the A10 suitable for battery powered applications. The nominal supply voltage is plus and minus 6 volts, and the quiescent current consumption is only 1.5 milliamps. Care is required over the choice of power supply, if batteries are not to be used, to ensure that the very low noise of the A10 is not degraded by series mode or common mode noise which may interfere with small signals. The A10 has very high rejection of common mode noise, but at nanovolt levels great care must be taken.
The A10 is small enough to mount on a p.c. board if required, and the case is made of Mumetal to give an extra degree of magnetic and electrostatic screening. The voltage and current offset controls are accessible with small insulated trimming tool through the two holes in the front. Care should be taken with these adjustments.
A10直流nV放大器说明
噪声
等效噪声电阻为20Ω。电压噪声取决于带宽。当上升时间为1s时，电压噪声峰峰值为1nV。噪声中没有1/f噪声成分。
Noise
Equivalent noise resistance is typically 20 ohms. Noise voltage depends on bandwidth, e.g. rise time constant 1 second gives a peak to peak noise voltage of 1 nanovolt. There is no 1/f component.
失调电压
可调节至零。温度系数为1nV/℃。
Offset Voltage
Adjustable to zero. T.C. typically 1nV per degree C
失调电流
可调节至零。温度系数为5pA/℃。
Offset Current
Adjustable to zero. T.C. better than 5pA per degree C.
增益和带宽
直流时开环增益超过5e12，在20kHz时降至单位1。放大器增益可以通过外部反馈电阻设置。内部反馈电阻的阻值为1Ω，精度为1%，温度系数为5ppm/℃。若要将增益设置为10,000，外部反馈电阻应为9999Ω。
Gain and Bandwidth
Greater than 5e12 at DC reducing to unity at 20 K Hz. Amplifier gain is set using an external feedback resistor.
The fixed internal feedback component is 1 ohm + / - 1% 5 ppm, so for a gain of 10,000, the feedback element must be 9999 ohms.
输入电阻
当开环增益设置为1,000,000时，输入阻抗超过1GΩ，并与输入响应时间函数相关。
Input Resistance
Greater than 1 G ohm, with gain set to 1 million or less, subject to time following an input step function.
源电阻
源电阻在20Ω至20kΩ范围时，A10遵守源热噪声特性。在源电阻低于20Ω时，噪声曲线基本平坦。
Source Resistance
The A10 closely follows the source Johnson noise characteristic from source resistance of 20 ohms up to approaching 20 K ohms.
With source resistances below 20 ohms the noise is substantially constant down to zero ohms.
输入电压
最大输入信号为±2mV。
Input Level
The A10 will operate with input voltages up to + / - 2mV.
输出电压
最大输出信号为±3V，负载电流为2mA（包括流经反馈电阻的电流）。
Output Level
The A10 will provide an output up to + / - 3V D.C. at 2mA load, including the current taken by the feedback resistor.
连接点
输入端为3mm的双头铜螺栓和铜螺母。其余连接点为M3的双头螺栓和螺母。
Connectors
The input connectors are 3mm studs and nuts in pure copper. All other connectors are M3 brass studs and nuts.
供电
最小供电电压为±5.5V，静态电流为2mA。最大供电电压为±12V。推荐供电为±6V。
Power Supply
Minimum + / - 5.5V at 2mA. Maximum + / - 12V. Nominal Supply +/- 6 volts.
尺寸和重量
长120mm，宽70mm，高35mm，铜螺栓高度6mm。重量为540g。
Dimensions and Weight
Length 120mm. Width 70mm. Height 35mm. + 6mm for terminals. Weight 540gm
固定
4个固定孔直径均为3mm，中心距为114mm*54mm。
Fixing
4 Holes required 3mm diameter. 114mm X 54mm.
反馈电阻
内部反馈电阻的阻值为1Ω，精度为1%，温度系数为5ppm/℃。外部反馈电阻连接在输出端（Output）和反馈端（Feedback）之间，设置值为Rfb=(要求增益-1)Ω，例如，所要求增益为10,000，那么需要将外部反馈电阻Rfb设为9999Ω。由于内部反馈电阻精度为1%，因而外部反馈电阻也需要1%精度。增益稳定性将为5ppm/℃加上外部反馈电阻的温度系数。
在输出端（Output）和反馈端（Feedback）之间并联有10pF电容。
Note. Feedback Components. There is an internal feedback resistor from the 'Feedback' terminal to the input 'Lo' of 1 ohm + / - 1% 5 ppm/degree C. The gain is set by connecting an external resistor from 'Output' to 'Feedback' . The value of this resistor is Rfb = (gain required - 1) ohms. i.e. Gain = 10,000, Rfb = 9999 ohms. As the internal feedback resistor has a tolerance of 1%, the external feedback resistor needs to be adjusted by +/- 1%. the gain stability will be 5ppm per degree C plus the stability of the applied feedback resistor.
There is a 10pF capacitor connected from 'Output' to 'Feedback'