NF has created this low noise AC signal pre-amplifier “CMP61102” specifically for the measurement of small AC signals and small noise superimposed on large DC voltage. The amplifier provides both great input protection performance and low noise characteristics. (Figure 2.) And the amplifier protects the circuit by limiting the maximum current applied to the inputs, plus the noise characteristics of the amplifier is very low at 2 nV/√Hz. The protection circuit can support DC voltage in the order of few tens of V, thus there is no concern of damages even when the output of a power supply or power amplifier is directly connected/disconnected.
The electrical performance of the low noise AC signal pre-amplifier is as shown in the Table 2 below. As long as the input voltage (DC signal + AC signal) is within ±40 V, the amplifier will never fail. The maximum input voltage extension to ±80 V is also possible. This product achieves both high gain and wide bandwidth, which has a gain of 60 dB and upper cutoff frequency of 3 MHz. In addition, the cutoff frequency of Low Pass Filter (LPF) is switchable to 7 levels.
In addition, power transformers that transform commercial power inputs are generally large and heavy. And the series regulator needs a large heat sink for heat release.
Table 2. Specifications of low noise AC signal pre-amplifier “CMP61102” (for reference)
|Maximum Input Voltage||±40 V
*Extension to ±80 V is possible
|Input Impedance||100 kΩ|
|Voltage Gain||60 dB|
|Equivalent Input Noise Voltage Density||2 nV/√Hz or less|
|Upper Cutoff Frequency||3 MHz|
|LPF Switching Function
(Upper cutoff frequency setting values)
|7 levels switchable via a rotary switch
10, 100, 1k, 10k, 100k, 1MHz, THRU
|Lower Cutoff Frequency||1 Hz
*can be extended to 0.1 Hz or less
|Maximum Output Voltage||±10 V|
*Please contact us in advance for customized products.