Author

# Chin Chang

Bio: Chin Chang is an academic researcher from Semtech. The author has contributed to research in topics: Inductor & Maxwell bridge. The author has an hindex of 1, co-authored 1 publications receiving 10 citations.

##### Papers

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Semtech

^{1}TL;DR: In this paper, it is revealed that the lossless current sensing structure is very similar to the well known Maxwell bridge and a "speedy capacitor" could be added to the LCS circuitry to significantly improve the sensed current signal to noise ratio and avoid jittery operation in wide DC-DC conversion ratio applications.

Abstract: In this paper, it is revealed that the lossless current sensing structure is very similar to the well known Maxwell bridge. The matching condition in lossless current sensing is the same as the balance equation in Maxwell bridge. In practice, it is difficult to meet the matching condition due to the parameter value variations. However, it is shown that in current mode control, at certain time constant mismatching situations, the circuit dynamic response actually could be improved. Furthermore, a "speedy capacitor" could be added to the lossless current sensing circuitry to significantly improve the sensed current signal to noise ratio and avoid jittery operation in wide DC-DC conversion ratio applications.

10 citations

##### Cited by

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24 Jul 2009

47 citations

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TL;DR: In this article, the authors proposed a current-mode hysteretic buck converter with a spur-free constant-cycle frequency-hopping controller that fully eliminates spurs from the switching noise spectrum irrespective of variations in the switching frequency and operating conditions.

Abstract: This paper proposes a current-mode hysteretic buck converter with a spur-free constant-cycle frequency-hopping controller that fully eliminates spurs from the switching noise spectrum irrespective of variations in the switching frequency and operating conditions. As a result, the need for frequency regulation loops to ensure nonvarying switching frequency (i.e., fixed spurs location) in hysteretic controllers is eliminated. Moreover, compared to frequency regulation loops, the proposed converter offers the advantage of eliminating mixing and interference altogether due to its spur-free operation, and thus, it can be used to power, or to be integrated within noise-sensitive systems while benefiting from the superior dynamic performance of its hysteretic operation. The proposed converter uses dual-sided hysteretic band modulation to eliminate the inductor current imbalance that results from frequency hopping along with the output voltage transients and low-frequency noise floor peaking associated with it. Moreover, a feedforward adaptive hysteretic band controller is proposed to reduce variations in the switching frequency with the input voltage, and an all-digital soft-startup circuit is proposed to control the in-rush current without requiring any off-chip components. The converter is implemented in a 0.35- μ m standard CMOS technology and it achieves 92% peak efficiency.

41 citations

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11 Jul 2011TL;DR: In this article, current through the inductor is sensed to determine when to turn off or on the switching transistors, and a summing circuit is applied to a PWM comparator to control the duty cycle of the switch.

Abstract: In a current mode controlled switching power supply, current through the inductor is sensed to determine when to turn off or on the switching transistors The inductor current has a higher frequency AC component and a lower frequency DC component The AC current feedback path, sensing the ramping ripple current, is separate from the DC current path, sensing the lower frequency average current Separating the current sensing paths allows the signal to noise ratio of the AC sense signal to be increased and allows the switching noise to be filtered from the DC sense signal The gain of the DC sense signal is adjusted so that the DC sense signal has the proper proportion to the AC sense signal The AC sense signal and the DC sense signal are combined by a summing circuit The composite sense signal is applied to a PWM comparator to control the duty cycle of the switch

38 citations

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TL;DR: In this article, a coupled sense winding method was proposed to increase the corner frequency of the sensing circuit by more than two orders of magnitude, which can be used to compensate for induced voltages due to the inductor.

Abstract: The lossless inductor current sensing method is well-known and is frequently applied in the measurement of output current in DC-DC converters due to its low cost and simplicity. This technique uses a low-pass filter that is matched to the inductance (L) and winding resistance to compensate for induced voltages due to the inductor. However, the waveform fidelity above the corner frequency of the inductor is generally poor due to large production tolerances and thermal drift. In this letter, we propose the use of a coupled sense winding, which increases the corner frequency of the sensing circuit by more than two orders of magnitude. We show, as an example, that for a 3.85 muH inductor the corner frequency of the measurement circuit can be increased from 36 Hz using the conventional approach to 5.8 kHz using the coupled sense winding method. Above the new corner frequency, a low-pass filter is still required but may now be constructed using a smaller capacitor and with improved high-frequency response.

13 citations

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01 Sep 2015

TL;DR: In this article, a low pass filter is used to estimate the inductance and the series resistance of the inductor coil in a single-phase boost-type switch-mode rectifier.

Abstract: Boost-type switch-mode rectifiers (SMR) commonly use a resistor or a magnetic current sensor to measure the instantaneous input or inductor current that is used as the feedback to the current controller. In this paper a novel current sensorless scheme is described that computes the inductor current from the measured inductor voltage in a single-phase boost-type SMR using an adaptive low pass filter. This calculation requires an estimate of the inductance and the equivalent series resistance of the inductor coil. Both these parameters are dependent on operating conditions and hence have to be updated continuously. This is done using an adaptive model of the inductor that computes these parameters of the inductor once in every half cycle of the input current. The adaptation scheme is robust against parameter variations. Simulation and experimental results confirm the effectiveness of the proposed technique which provides comparable performance to standard measured feedback current scheme both under steady-state and transient conditions.

9 citations