簡介
LNHS SP983c
LNHS SP983c 是瑞士Basel Precision Instruments的一款低雜訊電流放大器。 LNHS精選選雜訊最低的晶體管，出品低雜訊高穩定性I-V轉換器，它具有超低雜訊、出色的穩定性以及獨特的特性，如浮動輸入和可施加外部偏置電壓。 該裝置體積小、重量輕，可以方便地安裝在實驗裝置附近，直接安裝在擊穿盒或恒溫器上。 I-V轉換器的增益，從10^5到10^9 V/A，集成低通濾波器的截止頻率在30Hz到100kHz之間。 遠端控制單元可遠程調節增益和濾波器設置。 最大增益時帶寬為1.7kHz （ 10^9 V/A ），變化到最小增益時為600kHz （ 10^5 V/A ）。
我要諮詢LNHS SP983c 是瑞士Basel Precision Instruments的一款低雜訊電流放大器。 LNHS精選選雜訊最低的晶體管，出品低雜訊高穩定性I-V轉換器，它具有超低雜訊、出色的穩定性以及獨特的特性，如浮動輸入和可施加外部偏置電壓。 該裝置體積小、重量輕，可以方便地安裝在實驗裝置附近，直接安裝在擊穿盒或恒溫器上。 I-V轉換器的增益，從10^5到10^9 V/A，集成低通濾波器的截止頻率在30Hz到100kHz之間。 遠端控制單元可遠程調節增益和濾波器設置。 最大增益時帶寬為1.7kHz （ 10^9 V/A ），變化到最小增益時為600kHz （ 10^5 V/A ）。
可以在I-V轉換器輸入端提供±100 mV （SP983c ）、± 1 V （SP983c01 ）或± 2 V （SP983c02 ）的外部偏置電壓，這使得在任意偏置電壓下測量電流，進行對稱的源漏電壓偏置成為可能。 外部施加的輸入偏置電壓被內部減去，不在輸出信號里。
市面上的前置放大器在其輸入端都會產生很小的電壓偏置，但我們的I-V轉換器是唯一通過有源反饋環路，將輸入電壓偏置穩定在0.2 μV/K以下的前置放大器。 在元件所加電壓與μV級相關的實驗中，穩定的輸入電壓偏置非常有價值。 在其他商用儀器中，輸入電壓會隨時間漂移10s μV。
該元件是為低溫（稀釋冰箱）實驗而設計的。 針對大負載電容，例如低溫實驗中來自嚴重濾波引線的電容，IF3602輸入級進行了優化。 I-V變換器的輸出地與電源和計算機介面隔離，實驗電纜提供了測量接地。 這種接地方案有助於避免不需要電池的接地迴路，實現了超低雜訊測量。
我們為I-V轉換器的輸入級提供了兩種不同的J-FET選項：
LSK389A： 輸入電流雜訊較低
適用於：R > 1MΩ，C < 1nF （在10^8和10^9 V/A範圍內顯著）
IF3602 ： 輸入電壓雜訊略低
適用於：R < 1MΩ or C > 1nF
增益頻寬積為600 MHz，在大輸入電容時輸出雜訊明顯降低
The low-noise high-stability (LNHS) I to V Converter offers ultra-low noise, excellent stability, and unique features such as a floating input and the possibility to apply an external bias voltage. We carefully screen and select only the best, lowest noise transistors for the input stage.
The units are small and light and can easily be mounted close to the experiment, e.g., directly on the breakout box or the cryostat. The I to V converter offers five decades of gain, from 10^5 to 10^9 V/A, and an integrated low-pass filter with a cut-off between 30 Hz and 100 kHz. A remote control unit is available to adjust gain and filter settings remotely. The bandwidth varies from 1.7 kHz at maximum gain (10^9 V/A) to 600 kHz at minimum gain (10^5 V/A).
One may supply an external bias voltage of ±100 mV (model SP983c), ±1 V (model SP983c01) or ±2 V (model SP983c02) on the I to V converter input, making it possible to measure current at an arbitrary bias voltage or do symmetric source-drain voltage biasing. The externally applied input bias voltage is internally subtracted and does not go on top of the output signal.
While all preamplifiers put out a small voltage bias at their inputs, our I to V converter is the only preamplifier that stabilizes this input voltage bias with an active feedback loop to below 0.2 μV/K. In experiments where the voltage applied to the device is relevant to the μV level, the stabilized input voltage bias is very valuable. In other commercial instruments, the input voltages may drift by many 10s of μVs over time.
Our devices are designed for low-temperature (dilution fridge) experiments. The IF3602 input stage (see the input stage options below) is optimized for large load capacitances such as those from heavily filtered leads in low-temperature experiments.
The I to V converter's output ground is isolated from the power supply and the computer interface. Hence, the cables coming from the experiment provide the measurement ground. This grounding scheme helps avoid ground loops without a need for batteries and enables an ultra-low noise setup.
We offer two different J-FET options for the input stage of the I to V converter:
LSK389A: best for R > 1 MΩ and C < 1 nF
Lower input current noise
(significant in the 10^8 and 10^9 V/A ranges)
IF3602: best for R < 1 MΩ or C > 1 nF
Slightly lower input voltage noise.
Lager gain-bandwidth-product (600 MHz) makes output noise significant smaller at large input-capacitances.