Technique to improve CMRR at high frequencies in CMOS OTA-C filters

Blakiewicz, Grzegorz

doi:10.2478/bpasts-2013-0074

Cited by 2 publications

(2 citation statements)

References 16 publications

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“…The level of the supply voltage V o is controlled by a power management circuit, which additionally monitors volume of received energy and protects against excessive increase of the supply voltage V o during strong coupling between the transmitter and receiver. Too high supply voltage could damage low-voltage filters, amplifiers, and image processing circuits [12,13] inside the capsule. If the level of received power is too low, a tuning cycle is initialized to adjust parameters of the resonant circuit.…”

Section: Tuneable Receiver For Wireless Power Receptionmentioning

confidence: 99%

Automatic tuning of a resonant circuit in wireless power supply systems for biomedical sensors

Blakiewicz¹,

Jakusz²,

Jendernalik³

et al. 2016

Bulletin of the Polish Academy of Sciences Technical Sciences

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Abstract. In this paper, a tuning method of a resonant circuit suited for wireless powering of miniature endoscopic capsules is presented and discussed. The method allows for an automatic tuning of the resonant frequency and matching impedance of a full wave rectifier loading the resonant circuit. Thereby, the receiver tunes so as to obtain the highest power efficiency under given conditions of transmission. A prototype receiver for wireless power reception, fabricated in in AMS CMOS 0.35 µm technology, was used to verify correct operation of the proposed tuning. The prototype system produces a stable supply voltage, adjustable in the range of 1.2-1.8 V at a maximum output current of 100-67 mA, which is sufficient to power a typical endoscopic capsule. results of detailed analysis and experimental measurements show that with large changes of coupling, tuning of the resonant frequency and impedance adjustment must be applied in order to achieve sufficiently high efficiency of power transmission. The problem of a proper selection of a tuning circuit for biomedical sensors is further complicated by the need to obtain small size, and a requirement to work with a rectifier. Several types of tuning circuits for adaptation to changes in coil position were proposed in [3,[5][6][7][8]. Although the proposed solutions improve the transmission efficiency, they have certain limitations. For example, the solution [3] requires changes in distance between a coil and its coupling winding, which makes miniaturization impossible. Another tuning circuit, presented in [5] cannot work with certain rectifiers, because the circuit uses a matrix of capacitors that blocks flow of DC current required for proper operation of the rectifier. The solution [6] allows only for a limited adjustment to specified distance between transmitting and receiving coils, and therefore has a limited range of effective application. The other variants [7,8] only use frequency tuning, which considerably limits possibility of obtaining high efficiency of power transmission. In this paper the most difficult case, namely the wireless power transmission to an endoscopic capsule is considered. In this way, the proposed solution might find much wider application, both for powering the capsules as well as powering simpler devices while providing higher transmission efficiency than was previously possible to achieve. Furthermore, the tuning circuit can work with all types of rectifiers and can be largely miniaturized. In Section 2 conditions of power transmission to endoscopic capsules are outlined and discussed. The proposed tuning method and a tunable receiver for wireless power reception are presented in Section 3. In the next section results of measurements of an integrated prototype circuit are given. The final conclusions are summarized in the last section.

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Section: Tuneable Receiver For Wireless Power Receptionmentioning

confidence: 99%

Automatic tuning of a resonant circuit in wireless power supply systems for biomedical sensors

Blakiewicz¹,

Jakusz²,

Jendernalik³

et al. 2016

Bulletin of the Polish Academy of Sciences Technical Sciences

Self Cite

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“…The transconductance-capacitor (OTA-C) approach is often used for continuous-time filter design [1][2][3][4][5][6]. For high frequency applications, numerous circuit techniques to design OTA-C filters have been developed, using the gate-driven differential pair transconductors as input stages of the OTAs [7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Bulk linearized CMOS differential pair transconductor for continuous-time OTA-C filter design

Pankiewicz¹,

Szczepański²,

Wójcikowski³

2014

Bulletin of the Polish Academy of Sciences: Technical Sciences

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Abstract. In this paper, the MOS differential pair driven simultaneously from gates and bulk terminals is described. An approximated analytical solution of the voltage to current transfer function has been found for the proposed circuit. Four possible combinations of gate and bulk connections of the input signal are presented. Basing on the configuration giving the best linearity, the operational transconductance amplifier (OTA) has been designed and compared, by computer simulations, to the amplifier utilizing the gate driven classic MOS pair. 3 rd order filters using the OTAs with linearized and simple MOS pair have been designed and the resulting parameters have been compared. Linearization through the presented simultaneous use of gate and bulk terminals seems to be useful for low voltage applications.

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Technique to improve CMRR at high frequencies in CMOS OTA-C filters

Cited by 2 publications

References 16 publications

Automatic tuning of a resonant circuit in wireless power supply systems for biomedical sensors

Automatic tuning of a resonant circuit in wireless power supply systems for biomedical sensors

Bulk linearized CMOS differential pair transconductor for continuous-time OTA-C filter design

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