Abstract
This paper presents the design and testing of a low-noise programmable voltage source. Such a piece of instrumentation is often required as part of the measurement setup needed to test electronic devices without introducing noise from the power supply (such as photodetectors, resistors or transistors). Although its construction is based on known configurations, here the discussion is focused on the characterization and the minimization of the output noise, especially at very low frequencies. The design relies on a digital-to-analog converter, proper lowpass filters, and a low-noise Junction Field-Effect Transistors (JFET) based voltage follower. Because of the very low level of output noise, in some cases we had to resort to cross-correlation in order to reduce the background noise of the amplifiers used for the characterization of the programmable source. Indeed, when two paralleled IF9030 JFETs are used in the voltage follower, the output noise can be as low as 3 nV/√Hz, 0.6 nV/√Hz and 0.4 nV/√Hz at 1 Hz, 10 Hz and 100 Hz, respectively. The output voltage drift was also characterized and a stability of ±25 µV over 3 h was obtained. In order to better appreciate the performance of the low-noise voltage source that we have designed, its noise performances were compared with those of a set-up based on one of the best low-noise solid-state voltage regulators available on the market. Actual measurements of the current noise in a type-II superlattice photodetector are reported in which the programmable source was used to provide the voltage bias to the device.
Highlights
Identification and measurement of noise signals are crucial for many electronic devices [1]
While the design is inspired from [29], a number of modifications are introduced that in much lowerlower levelslevels of noise. While such a piece of of instrumentation many result in much of noise. While such a piece instrumentationcan canbe beeffective effective in in many applications in the field of low frequency noise measurements, the design originated from the need applications in the field of low frequency noise measurements, the design originated from the need for for a low-noise bias source to be used for investigating the noise in a novel infrared detector at a low-noise bias source to be used for investigating the noise in a novel infrared detector at frequencies frequencies down to the effectiveness of the design we propose is demonstrated by the down to 1 Hz
The measurement setup for noise measurements is reported in voltage source (LNVS) such as the one we propose is essential in order to obtain correct results in the characterization of electron devices
Summary
Identification and measurement of noise signals are crucial for many electronic devices [1]. This is important for device characterization, and for the study and a deep understanding of microscopic physical phenomena and technologies. In the case of biased devices (such as transistors [4,5], varistors [6], photodetectors [7,8,9,10,11,12,13] and other materials [14,15,16,17]), the noise introduced by the biasing devices is very important because it can mask the noise generated by the devices being investigated or limit the performances of the designed instruments. In order to perform reliable noise characterization, we need to resort to ultra-low-noise power supply units that introduce negligible noise levels compared to those generated by the device-under-test (DUT). The fact that we can only use a combination of elementary cells limits the resolution that can be obtained in setting the Electronics 2020, 9, 1245; doi:10.3390/electronics9081245 www.mdpi.com/journal/electronics
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