Electrical stability of a MEMS-based AC voltage reference

Modeling the effect of mobile ion contamination on the stability of a microelectromechanical resonator

“…5 In this kind of experiment, for example, the initial 30 V bias followed by À16 and À20 V DC-biases, the asymmetric charge concentrations would significantly change the magnitude of the drift. It is known that a fast alternating DC-biasing scheme results in a smaller drift in frequency 16 or in reference voltage, 8 as compared to a constant DC bias. This can be explained by mobile ions having such low mobility that they cannot follow the alternating bias quickly enough.…”

“…(1) and (2)]. 8 However, when we consider the mobile ion contamination, this is not necessarily a valid approach, since the drift minimum should occur at the DC-bias voltage, which minimizes the movement of the mobile charge. However, the observation 17 of a drift minimum at a voltage different than À V bi in the structure containing a 50 nm oxide layer suggests that the drift might be due to low-mobility ionic contamination, meaning that a second-order effect dominates the drift.…”

“…5 The resonant-frequency drift is one of the major barriers to the commercialization of silicon MEM resonators for timing applications. 6,7 Since the contamination is almost inevitable at present, it seems reasonable to also assume that mobile charge contamination can be a significant source of drift in other capacitive MEM components, such as voltage references 8 and accelerometers, which normally operate at lower electric fields than RF-MEM switches.…”

Microcomposants électromécaniques pour la réalisation de références de tension en courant alternatif

“…Ainsi, la stabilité de ces structures MEMS a été étudiée théoriquement et expérimentale-ment. Un des résultats marquants est lié à la mise au point d'une référence de tension AC de 9 V, sur la base d'un MEMS accéléromètre commercial, montrant une stabilité de la tension à 100 kHz de l'ordre de 2 × 10 −6 sur trois semaines de mesure [22]. Cette stabilité a toutefois été obtenue en appliquant des corrections dues aux effets de température, d'humidité et de pression, mais surtout par la compensation de la tension continue dite « built-in voltage » générée à aux interfaces métal-semi-conducteur dans le système.…”

Null detector and AC voltage reference based on MEMS

“…We have earlier demonstrated relative voltage drift below 2·10 -6 after correcting the raw data for changes in ambient pressure and temperature for both AC and DC voltage references based on MEMS [4], [5]. More recently, the LNE group has demonstrated stability of a MEMS-based AC voltage reference with standard deviation of 1·10 -6 without any error corrections on the raw data [6].…”