On the reduction of thermal and flicker noise in ENG signal recording amplifiers

Abstract

Because of the extremely low amplitude of the input signal, the design of electro-neuro-graph (ENG) amplifiers involves a special care for flicker and thermal noise reduction. The task becomes really challenging in the case of implantable electronics, because power consumption is restricted to few hundreds lW. In this work, two different circuit techniques aimed to reduce flicker and thermal noise, in ultra-low noise amplifiers for implantable medical devices, are demonstrated. The circuit design, and measurement results are presented, in both cases showing an excellent performance, and noise to power consumption trade-off. In the first circuit, a very simple low-pass G m -C chopper amplifier is used for flicker noise cancellation. It consumes only 28 mW, with a measured input referred noise and offset of 2 nV ffiffiffiffiffiffi Hz p , and 2.5 lV, respectively. In the second circuit, a ultra-low noise amplifier, a energyefficient DC-DC down-converter, and low voltage design techniques are combined, for the reduction of thermal noise with a minimum power consumption. Measured input referred noise in this case was 5.5 nV ffiffiffiffiffiffi Hz p at only 380 lW power consumption. Both circuits were fabricated in a 1.5 lm technology.

Very low frequency cyclostationary 1/f noise in MOS transistors

“…4, but the reappearance of 1/f spectrum for even lower frequencies as reported in [5], [6] was not. The starting assumption in the previous section was in (9) that the emission probabilities of all the traps are affected by variations of V GS in the same way. But remembering section II-B, where a non-uniform spatial distribution of the traps result in different noise PSD γs, a non uniform spatial m-factor for eq.…”

“…But to further reduce the noise of the mirrors, the OTA is connected in a chopper configuration like in Fig.6-bottom. This topology was demonstrated in [9], but in the present embodiment four phases are utilized: during φ 2 , φ 4 , the DUTs are in 'off' state, during φ 1 them are in 'on' state as well as in φ 3 but in the latter the connection of the switch matrix of Fig. 6 is flipped.…”

“…6 is flipped. Flipping the DUTs can be associated to flicker noise modulation, which is demodulated back in the output capacitors (chopper principle [4], [9]). …”

Optimization of Excitation and Detection Modes to Detect Ultra-Small Amounts of Semiconductor Quantum Dots Based on Cadmium Selenide

“…(3) Because of (3), the simplest approach to detect a low-power fluorescent signal is to use the continuous wave mode of excitation and a photoreceiver with a DC transimpedance amplifier. However, this approach is not used in practice because of low-frequency noises, including flicker noise [27,40,41], burst noise [40], and ambient light fluctuation [42][43][44][45]. At a frequency below ~1 kHz, the value of additional noise equivalent power ΔNEP(f) may significantly exceed the spectral density of thermal noise even in the case of flicker noise alone [27,46].…”

“…A photoreceiver based on a Si p-i-n photodiode is the most promising. In this case, to reduce the ambient light influence, both the modulation mode [26][27][28] and the pulsing mode [29,30] of fluorescent label excitation are used. In the case of the pulsing mode of excitation, the fluorescent signal is recorded within a short time period corresponding to the excitation lifetime of fluorescent labels.…”