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.
![](images/1-12.jpg)
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Information
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Measurement example
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Customization
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.
![](images/sa200_freq_vs_inputrange.png)
Output noise - Frequency response
Supports models with frequency ranges up to 500MHz. Achieves low noise specifications compared to competitors.
![](images/sa200_freq_vs_noise-1.jpg)
Output noise – input impedance characteristics
An amplifier suitable for the signal source resistance of the sensor can be selected. Achieves low-noise signal output.
![](images/sa200_zin_vs_noise-1-1.jpg)
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)
![](images/SA200_100_w120.gif)
![](images/SA200_010k_w120.gif)
![](images/SA200_100k_w120.gif)
![](images/SA200_001M_w120.gif)
SA-220F5 (1kHz to 80MHz, 0.5nV/√Hz)
![](images/SA220_001k_w120.gif)
![](images/SA220_001M_w120.gif)
![](images/SA220_010M_w120.gif)
![](images/SA220F5_30MHz-1.jpg)
SA-230F5 (1kHz to 100MHz, 0.25nV/√Hz)
![](images/SA230_001k_w120.gif)
![](images/SA230_010M_w120.gif)
![](images/SA230F5_30MHz.jpg)
![](images/SA230F5_100MHz.jpg)
SA-240F5 (DC to 20MHz, 1.2nV/√Hz)
![](images/SA240_100_w120.gif)
![](images/SA240_100k_w120.gif)
![](images/SA240_001M_w120.gif)
![](images/SA240_010M_w120.gif)
SA-250F6 (100Hz to 250MHz, 0.25nV/√Hz)
![](images/SA250F6_100kHz.jpg)
![](images/SA250F6_10MHz.jpg)
![](images/SA-250F6_100MHz.jpg)
![](images/SA250F6_250MHz.jpg)
SA-251F6 (1kHz to 500MHz, 0.25nV/√Hz)
![](images/SA251F6_100kHz.jpg)
![](images/SA251F6_10MHz.jpg)
![](images/SA-251F6_100MHz.jpg)
![](images/SA-251F6_500MHz.jpg)
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)
![](images/28_img_sig_analyzer_7.6.jpg)
![](images/25_ps_noise_none-1-1.jpg)
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)
![](images/30_img_sig_analyzer_230.jpg)
![](images/27_ps_noise_sa230-1.jpg)
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*
![](images/sa200F3_sine_55Hz_LPF300Hz.png)
LPF=300Hz
![](images/sa200F3_sine_550Hz_LPF3kHz.png)
LPF=3kHz
![](images/sa200F3_sine_5500Hz_LPF30kHz.png)
LPF=30kHz
![](images/sa200F3_sine_55kHz_LPF300kHz.png)
LPF=300kHz
Real-time signals of 5μVp-p observed
Waveform without LPF
*Using an appropriate LPF can reduce overall noise as shown above.
![](images/sa200F3_sine_55kHz_LPF1MHz.png)
Challenging the signal detection limit (nV repetitive signal)
Connect multiple SA series units and observe using the averaging function of the oscilloscope.
Block diagram
![](images/fig_sa200_block_2_new.jpg)
Results
- Input: 4nVp-p@55Hz, Pulse width: 1.82ms
- LPF measurement bandwidth: 1kHz
- Averaging process: 10,000 times
![](images/4nVp-p.jpg)
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
![](images/41_img_80ms-1.jpg)
- 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
![](images/42_img_8ms-2.jpg)
- 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
![](images/43_noise-figure_sa251-1.jpg)
Significant time reduction from 8ms to 3μs and the noise figure also improved