|   Japanese   |   Chinese   |

Low-noise preamplifier selection guide

Single-ended 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 impedance Input Voltage noise Input current noise Noise figure
SA-200F3 Single-ended 40dB DC to
800kHz
1kΩ/
10kΩ/
100kΩ
0.5nV/√Hz 2.2pA/√Hz -
SA-220F5 46dB 1kHz to
80MHz
1MΩ 0.5nV/√Hz 200fA/√Hz -
SA-240F5 40dB DC to
20MHz
1MΩ/
100MΩ/
OPEN
1.2nV/√Hz 5fA/√Hz -
SA-230F5 46dB 1kHz to
100MHz
50Ω 0.25nV/√Hz 5pA/√Hz 0.6dB
NEW
SA-250F6
40dB 100Hz to
250MHz
50Ω 0.25nV/√Hz 5pA/√Hz 0.6dB
NEW
SA-251F6
40dB 1kHz to
500MHz
50Ω 0.25nV/√Hz 8pA/√Hz 0.9dB

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 500MHz. 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

  • Upper waveform: Amplifier output
  • Lower waveform: Output after passing through amplifier output latter-stage LPF (1MHz) (reference)

SA-200F3 (DC to 800kHz, 0.5nV/√Hz)

100Hz
10kHz
100Hz
1MHz

SA-220F5 (1kHz to 80MHz, 0.5nV/√Hz)

1kHz
1MHz
10MHz
30MHz

SA-230F5 (1kHz to 100MHz, 0.25nV/√Hz)

1kHz
10MHz
30MHz
100MHz

SA-240F5 (DC to 20MHz, 1.2nV/√Hz)

100Hz
100kHz
1MHz
10MHz

SA-250F6 (100Hz to 250MHz, 0.25nV/√Hz)

100k
10MHz
100MHz
250MHz

SA-251F6 (1kHz to 500MHz, 0.25nV/√Hz)

100k
10MHz
100MHz
500MHz

Measurement example

Output noise density measurement of low-noise power supplies

Measurement of the output noise density of the low-noise power supply LP5394 using a signal analyzer.
Better measurement results were obtained by using the SA-200 series.

Measurement result of signal analyzer (equivalent input noise 7.6nV/√Hz)

True output noise density cannot be measured due to noise generated by the signal analyzer

Measurement result of signal analyzer and SA-230F5 (input conversion noise 0.25nV/√Hz)

*Graphs are shown with the gain of SA-230F5 corrected.

The sensitivity was improved by more than 20 times and measurement between 2 kHz and 40 kHz became possible.

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

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

SA-200F3

  • 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

Real-time signals of 5μVp-p observed

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.

Block diagram

Results

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

4nVp-p signal detected

Customization

Bandwidth modification

  • Change frequency response (extend low and high cutoff frequencies)
  • Change gain (e.g. 46d to 40dB)
  • Reduced overload recovery time
  • Multi channel Multi-channel low-noise system

Change frequency response

Standard Customized
SA-220F5 1k to 80MHz 1k to 130MHz
SA-230F5 1k to 70MHz 1k to 110MHz
SA-240F5 DC to 20MHz DC to 40MHz

Reduced overload recovery time (for MRI/NMR)

In MRI/NMR, waveforms are observed immediately after a change from a large signal input to a small signal.
Therefore, a short overload recovery time is required for the amplifier to transition from a large signal input saturation state to a normal state.
Customized products with greatly reduced overload recovery time are available.

Customization based on SA-250F6

  • Overload recovery time: 80ms → 50μs
  • Frequency response: 100Hz to 250MHz → 20kHz to 10MHz
  • Equivalent input noise voltage density: 0.5nV/√Hz@2MHz (unchanged)
  • Size: 50 x 40 x 11.5 mm (75% volume reduction)

Significant time reduction from 80ms to 50μs

Customization based on SA-251F6

  • Overload recovery time: 8 ms → 3 μs
  • Noise figure: 1.8 dB → 1.3 dB (improved at 500 MHz)
  • Frequency response: 1kHz to 500MHz → 3MHz to 500MHz

Significant time reduction from 8ms to 3μs and the noise figure also improved

Top