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Fully integrated on-time-based mode control is utilized to achieve an efficient mode control of a PWM/PFM mode buck converter for implantable medical devices. The proposed method predicts load current from the on-time of the power switches of the buck converter and does not require an additional current sensor. Additional passive components for load current estimation are not required in this approach. Moreover, this method consumes less control power and requires a smaller area compared with other circuits used for load current prediction. The proposed dual mode buck converter is fabricated using TSMC $0.18~\mu \text{m}$ CMOS technology. The active chip area is 0.58 x 0.46 mm2. The input voltage range is 2.2–5.0 V, the output voltage is 1.8 V, and the load current range is 0.2–100 mA. The experimental results demonstrate the proper mode transition under step-up/down load current transient. The peak power conversion efficiency was approximately 94 % at 50 mA, and the minimum efficiency was approximately 77 % within the load current range. [ABSTRACT FROM AUTHOR]

A photovoltaic (PV) energy harvesting system with 2-Dimensional Fast Maximum Power Point Tracking (2-D FMPPT), based on the hill climbing (HC) MPPT technique is proposed. The 3-step MPPT modes for the energy harvesting system are employed to obtain KVOC that is independent of environmental effects such as irradiance and radiated temperature. The system consists of a dynamic peak transducer power sensor (DPTPS), Coarse (1st) FMPPT mode, Ton Increment/Decrement Mode, Fine (2nd) mode, MPPT logics, and a controller. The system can handle a voltage range of 0.5 V to 2.4 V and a power range of 1.4 mW to 119 mW. A peak MPPT efficiency of 99.4% and over 96.1% MPPT efficiency in 1 k to 50 k illuminance are achieved. The proposed system is fabricated on 0.18- $\mu m$ CMOS process and occupies an active area of 1.4 mm2. [ABSTRACT FROM AUTHOR]

In this paper, a fully integrated active rectifier with triple feedback loops is proposed to enhance power conversion efficiency (PCE) over a wide loading range by calibrating both the gate transition timing and power switch size. The on- and off-transitions of the power switches are calibrated using a hybrid delay-based gate control circuit (HDGCC) with hybrid feedback loops. Conventional active rectifiers that only focused on calibrating the gate transition timing of a NMOS power switch with a fixed power switch size exhibit a low PCE when the loading condition deviates from the predetermined range. Thus, an automatic size selector based on a third feedback loop is proposed, which changes the power switch size based on the loading condition and ensures a stable operation of the hybrid loops by maintaining the voltage drop across the NMOS switches. An active rectifier was fabricated using the standard 0.18 μm CMOS process. The effectiveness and robustness of the two-dimensional calibration were verified through measurements under an AC input voltage ranging from 2.5 to 5.0 V and an output power ranging from 1.25 to 125 mW. The peak voltage conversion ratio and peak PCE were 97.6% and 95.0%, respectively, at RL = 500 Ω. [ABSTRACT FROM AUTHOR]

This brief presents a readout IC with a 20 V high-voltage (HV) transmitter (Tx) and On-Chip Differentially Modulated Time-Interleaved Sensing Method (DM-TISM) in a BCD process for a mutual-capacitive Transparent Fingerprint Sensor (TFPS) in order to achieve high SNR, AC & DC offset reduction, high noise immunity, and compensate for the signal loss under thick cover glass. A proposed readout IC with on-chip DM-TISM is composed of 42 identical HV Tx channels, 32 identical Rx channels, and a diamond-patterned TFPS. The performance results including those for transient noise show that the DM-TISM achieves greater SNR than conventional TISM. The measured raw data show that the proposed readout IC achieves SNR of 32 dB with current consumption of 25 mA for the Tx and 13 mA for the Rx. It can be applied to any type of mobile device that needs fingerprint recognition. The ICs for the Tx and Rx are fabricated using 0.25- $\mu \text{m}$ BCD process and 0.18- $\mu \text{m}$ CMOS process with $1.6\,\,\mathrm {mm} \times 3.5$ mm and $2.5\,\,\mathrm {mm} \times 2.5$ mm areas, respectively. [ABSTRACT FROM AUTHOR]

An instantaneous power consuming level shifter is presented in this brief to increase the dc converter efficiency. The level shifter is used in a high-side power switch driver to remove the external capacitor which is used in bootstrap technique. The level shifter consumes power only during the transition period. A delay cell is used to turn the level shifter off to reduce the power consumption period. An output voltage detector is added to turn the level shifter off even before the delay time. An asynchronous discontinuous conduction mode buck converter is designed to verify the performance of the level shifter. Simulation results show that the power consumption of the proposed level shifter decreased by 66%, while the converter efficiency increased by the maximum of 9% compared to results obtained for a conventional level shifter. The converter is fabricated using the TSMC 0.18- $\boldsymbol {\mu }\text{m}$ BCD process and it operates within an input range of 2–5 V when the current varies from 400 $\boldsymbol {\mu }\text{A}$ to 18 mA and delivers an output voltage of 1.8 V. [ABSTRACT FROM AUTHOR]

Wireless power transfer (WPT) technology applied to implantable medical devices (IMDs) significantly reduces the need for battery replacement surgery health conditions. This paper presents an on-/off-time sensing-based load-adaptive mode control of triple mode buck converter for implantable medical devices; the converter can adjust the control mode for low power consumption and achieve high power conversion efficiency (PCE) under a small active area. The three modes in the proposed system are the pulse width modulation (PWM), pulse frequency modulation (PFM), and ultra-low power (ULP) modes. The on-time sensor can be used to adjust the system from PWM to PFM modes, and the off-time sensor can be used to adjust the system from PFM to ULP modes. It is fabricated using TSMC 0.18 µm CMOS technology. The input voltage lies in the range 2.2-5.0 V, the output voltage is 1.8 V, and the load current lies in the range 0.05-200 mA (x4000). The experimental results demonstrate the seamless mode transition under the step up/down load transient response. The peak PCE is approximately 94.3% at the 80 mA and the minimum PCE is approximately 65.4% within the load current range.