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Wide-band-gap devices can provide much faster switching speed. But the dv/dt of switching node voltage also becomes much higher, causing potential common mode noise issue. On the other hand, PCB winding transformer has significant large inter-winding capacitance, which provides a low impedance path for common mode noise. In this paper, a symmetrical resonant converter as well as a symmetrical PCB...
Magnetically-coupled resonant wireless power transfer (MCR-WPT) offers a novel technique to transfer power over a long distance with high efficiency. A half bridge inverter with series-resonant structure is designed as driver source for WPT system in this paper. The frequency is up to 0.9MHz, which is very higher than traditional power electronic converter. The relationship between output power, transmission...
These days inductor current ripple based ‘current mode constant on time (CMCOT)’ control is widely used in voltage regulators (VRs) for its higher light load efficiency, higher bandwidth and simple compensation network. In today's VRs, high load current with very high slew rate is a very common requirement in microprocessor or memory applications. One issue of this ripple based CMCOT control is that,...
This paper proposes a novel ac-to-dc adaptor circuit with ultra-high power density and efficiency, which is based on a two-stage topology, consists of a bridgeless boost converter followed by a LLC converter. The bridgeless boost converter is in charge of regulating output voltage and minimizing bulk capacitor, while the LLC converter is operated as a dc transformer (DCX) and plays a role of providing...
This paper presents a new current mode control using charge control concept to improve the performances of the constant on time control. These days, constant on time control is widely used in VR applications for its higher light load efficiency and higher bandwidth design capability. In this constant on time configuration, inductor current ripple based current mode control is very popular in today's...
Synchronous rectifier (SR) is widely used in flyback converter to reduce the output side conduction loss in order to meet the system conversion efficiency requirement. The conventional SR driving methods are not suitable for high frequency (>500kHz) application. This paper proposes a novel SR driving method for MHz flyback converter operating at critical conduction mode (CRM). A RC network is in...
Car black boxes operate mostly in sleep mode, which requires high efficiency for light load. We propose two schemes to improve light load efficiency of the 3-level buck converter proposed by Reusch. The first scheme is to adopt constant ON-time control with DCM for light load. The second scheme is to shut down the gate drivers for the two bottom MOSFETs allowing Schottky diodes in parallel to conduct...
A simple third-order equivalent circuit model of series resonant converter (SRC) is proposed in this paper. Up to now, the most successful equivalent circuit model of SRC is based on extended describing function concept, which is proposed by Dr. E. Yang [30]. However, the equivalent circuit is a complicated fifth-order circuit with the cross-coupling effect and no analytical solution is provided for...
A 14-b 100-MS/s pipeline analog-to-digital converter (ADC) is presented. The ADC uses six 4-b stages with 2-b interstage redundancy to relax the requirements of Sub-ADC nonlinearity and interstage offset. The ADC, implemented in a 0.18-μm CMOS process, achieves 70.3-dB signal-to-noise and distortion ratio (SNDR), 83.7-dB spurious free dynamic range (SFDR) and 11.3 effective number of bit (ENOB) with...
In this paper, a digital calibration algorithm, based on original radix 2 off-line algorithm, is employed to calibrate a 4 stages, 12 bits pipelined Analog-to-Digital Converter(ADC). The detail implementation process of this algorithm, from algorithm design to circuit structure, is presented. The simulation results show that the calibrated ADC achieves SNR of 73.9 dB, SNDR of 73.3 dB, SFDR of 84.2...
This paper proposes a two-stage multi-channel LED driver, which contains a buck converter as the first stage and a multi-channel constant current (MC3) CLL resonant converter as the second stage. The forward current of one specific LED string is sensed for feedback control to regulate the bus voltage, which is also the input voltage of the MC3 CLL resonant converter. In contrast, the MC3 CLL is unregulated...
Recently, capacitor current ramp compensation, which features fastest transient response, has been proposed to stabilize V2 control with low equivalent-series-resistance (ESR) capacitor. However, it is found that the design of capacitor current sensing gain and the time-constant mismatch of sensing network may lead to oscillatory or slow transient response, so both issues are investigated in this...
The cascode structure is widely used for high voltage normally-on wide-band-gap devices. However, the interaction between the high voltage normally-on device and the low voltage normally-off Si MOSFET may induce undesired features. This paper analyzes the voltage distribution principle during the turn-off transition as well as the zero-voltage-switching (ZVS) principle during the turn-on transition...
This paper presents a 3rd order single loop continuous-time sigma-delta modulator (CTSDM) based on a 4-bit 2b/cycle SAR quantizer which reduces power consumption and chip area. The proposed high speed 2b/cycle SAR quantizer employs switchback capacitor switching procedure to obtain a more power efficient quantizer and a smaller variation of common-mode voltage which alleviates the effect of dynamic...
This paper presents an energy efficient high speed DAC structure that is implemented in a 10-bit 150MSample/s successive approximation register (SAR) ADC. To reduce energy consumption and improve ADC linearity, a segmented pre-quantize and bypass architecture is proposed to avoid unnecessary switching of high-weight capacitors based on the results of pre-quantization. Time required for one bit cycling...
This paper presents a high speed parallel segmented capacitive DAC that is implemented in a 10-bit 150MSample/s successive approximation register (SAR) ADC. Compared to converters that use the conventional structure, the speed of converting one bit digital code can be 4 times faster while the power remains relatively low. In the switching procedure, a small capacitor array is used to determine the...
A new equivalent circuit model is presented to predict the small-signal characteristic of current-mode control with DCR current sensing accurately, and a simple auto-tuning method is proposed to solve the issue of time constant mismatch in DCR current sensing. The model shows that the mismatch between the current sensing RC network and the output inductor makes the output impedance deviate away from...
V2 control and its variety named ripple-based control, are popular control schemes in point-of-load Buck converters and Voltage Regulators for microprocessor. This control scheme is elegant when output capacitors with sufficient ESR are employed, such as OSCON capacitors. However, in most cases with small-ESR capacitors, such as ceramic capacitors, instability problem will occur. Up to now, no equivalent...
As an essential part in a power converter, the magnetic cores and their design play an important role in achieving high efficiency and high power density. Accurate measurement of the core loss is important to their optimization. To improve the measurement accuracy, previous methods were proposed to cancel the reactive voltage of the testing core by a cancellation capacitor or inductor. However, the...
This paper presents an accurate analytical model to calculate the power loss of a high voltage Gallium Nitride high electron mobility transistor (GaN HEMT) in cascode configuration. The proposed model considers the package and PCB parasitic inductances, the nonlinearity of the junction capacitors and the transconductance of the cascode GaN transistor. The switching process is illustrated in detail,...
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