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Low-noise preamplifier selection guide

Differential input type

  • Reliably amplify a wide range of voltage signals between sub-µV and several mV
  • Lineup of models supporting a wide frequency range between DC and up to 500MHz
  • The most suitable model can be selected according to the signal source resistance.

Information

Lineup

Input type Gain Bandwidth Input resistance Noise voltage density Noise current density Noise figure
SA-410F3 Differential input 40dB DC to
1MHz
1kΩ/
10kΩ/
100kΩ
0.75nV/√Hz 4.5pA/√Hz -
SA-420F5 46dB 1kHz to
80MHz
1MΩ 0.9nV/√Hz 100fA/√Hz -
SA-421F5 46dB 30Hz to
30MHz
1MΩ 0.5nV/√Hz 100fA/√Hz -
SA-430F5 46dB 1kHz to
100MHz
50Ω 0.35nV/√Hz 7pA/√Hz 1.0dB
SA-440F5 40dB DC to 20MHz 1MΩ/
100MΩ/
OPEN
1.8nV/√Hz 25fA/√Hz -

Input voltage - Frequency response

The model line-up supports a wide voltage input range. Includes extremely small voltages of less than 1 μV.

Output noise - Frequency response

Supports models with frequency ranges up to 100MHz. Achieves low noise specifications compared to competitors.

Output noise - Input impedance Characteristics

An amplifier suitable for the signal source resistance of the sensor can be selected. Achieves low-noise signal output.

Pulse response

Output waveform comparison at 100μVp-p square wave input

SA-410F3 (DC to 1MHz, 0.75nV/√Hz)

100Hz
10kHz
100Hz
1MHz

SA-420F5 (1kHz to 70MHz, 0.9nV/√Hz)

1kHz
100kHz
10MHz
30MHz

SA-421F5 (30Hz to 30MHz, 0.5nV/√Hz)

1kHz
100kHz
10MHz
30MHz

SA-430F5 (1kHz to 100MHz, 0.35nV/√Hz)

1kHz
10MHz
30MHz
100MHz

SA-440F5 (DC to 20MHz, 1.8nV/√Hz)

100k
100kHz
1MHz
10MHz

Measurement example

Challenging the signal detection limit (µV real-time signal)

Small signals amplified by the SA series are observed with an oscilloscope.

SA-410F3

  • Input signal: 5μVp-p, sine wave
  • Oscilloscope: 1MHz bandwidth
  • LPF: Connected after the amplifier and set a cutoff frequency about 5 times the signal frequency*
Input 55Hz
LPF=300Hz
Input 550Hz
LPF=3kHz
Input 5.5kHz
LPF=30kHz
Input 55kHz
LPF=300kHz

Detects 5µVp-p real-time signals

Waveform without LPF

*Using an appropriate LPF can reduce overall noise as shown above.

Input 55kHz

Challenging the signal detection limit (nV repetitive signal)

Connect multiple SA series units and observe using the averaging function of the oscilloscope.

Measurement block diagram

Measurement results

SA-410F3

  • Input: 4nVp-p@55Hz, Pulse width: 1.82ms
  • Measurement bandwidth: 1kHz
  • Averaging process: 10,000 times

4nVp-p signal detected

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