Showing papers by "Yasuhiro Sugimoto published in 2012"
TL;DR: By using a quadratic compensation slope, a CMOS current-mode buck DC-DC converter with constant frequency characteristics over wide input and output voltage ranges has been developed and the frequency characteristics become constant, the frequency bandwidth is maximized.
Abstract: By using a quadratic compensation slope, a CMOS current-mode buck DC-DC converter with constant frequency characteristics over wide input and output voltage ranges has been developed. The use of a quadratic slope instead of a conventional linear slope makes both the damping factor in the transfer function and the frequency bandwidth of the current feedback loop independent of the converter's output voltage settings. When the coefficient of the quadratic slope is chosen to be dependent on the input voltage settings, the damping factor in the transfer function and the frequency bandwidth of the current feedback loop both become independent of the input voltage settings. Thus, both the input and output voltage dependences in the current feedback loop are eliminated, the frequency characteristics become constant, and the frequency bandwidth is maximized. To verify the effectiveness of a quadratic compensation slope with a coefficient that is dependent on the input voltage in a buck DC-DC converter, we fabricated a test chip using a 0.18µm high-voltage CMOS process. The evaluation results show that the frequency characteristics of both the total feedback loop and the current feedback loop are constant even when the input and output voltages are changed from 2.5V to 7V and from 0.5V to 5.6V, respectively, using a 3MHz clock.
3 citations
TL;DR: In this paper, the authors proposed a high-speed simulation method for switching converters using a behavioral simulation tool without using a SPICE-like analog simulator, which is called NSTVR (New Simulation Tool for Voltage Regulators).
Abstract: We propose a fast and precise transient response and frequency characteristics simulation method for switching converters. This method uses a behavioral simulation tool without using a SPICE-like analog simulator. The nonlinear operation of the circuit is considered, and the nonlinear function is realized by defining the nonlinear formula based on the circuit operation and by applying feedback. To assess the accuracy and simulation time of the proposed simulation method, we designed currentmode buck and boost converters and fabricated them using a 0.18-μm highvoltage CMOS process. The comparison in the transient response and frequency characteristics among SPICE, the proposed program on a behavioral simulation tool which we named NSTVR (New Simulation Tool for Voltage Regulators) and experiments of fabricated IC chips showed good agreement, while NSTVR was more than 22 times faster in transient response and 85 times faster in frequency characteristics than SPICE in CPU time in a boost converter simulation. key words: DC-DC converter, behavioral analog simulation, high-speed, highly accurate, buck converter, boost converter
1 citations
20 May 2012
TL;DR: The calculated gain and phase frequency characteristics from the small signal equivalent circuit model with stray capacitors have agreed very well with SPICE simulation results of the actual circuit especially at high frequencies above 1 GHz.
Abstract: A 1.8-V operational 3-stage Amplifier with a 99 dB of voltage gain, a 650 MHz of the unity-gain frequency bandwidth and 54 degrees of phase margin is realized. It has two pairs of a resistor and a capacitor in series as feedback elements and a feed-forward transconductance amplifier to perform threefold phase compensation. In order to apply this threefold phase compensation scheme to realize a high gain and high frequency 3-stage amplifier with enough phase margin, the small signal equivalent circuit model with stray capacitors at the output of each stage of amplifier is newly developed and the small signal transfer function including those stray capacitors are formulated. The transfer function is factorized into poles and zeros so that their relationship and influence on the frequency characteristics can be examined. The 3-stage amplifier is actually circuit designed by using 0.18µm CMOS devices. The calculated gain and phase frequency characteristics from our equivalent circuit model with stray capacitors have agreed very well with SPICE simulation results of the actual circuit especially at high frequencies above 1 GHz.
01 Jan 2012
TL;DR: The comparison in the transient response and frequency characteristics among SPICE, the proposed program on a behavioral simulation tool which is named NSTVR (New Simulation Tool for Voltage Regulators) and experiments of fabricated IC chips showed good agreement, while N STVR was more than 22 times faster in transient response & frequency characteristics than SPICE in CPU time in a boost converter simulation.
Abstract: SUMMARY We propose a fast and precise transient response and frequency characteristics simulation method for switching converters. This method uses a behavioral simulation tool without using a SPICE-like analog simulator. The nonlinear operation of the circuit is considered, and the nonlinear function is realized by defining the nonlinear formula based on the circuit operation and by applying feedback. To assess the accuracy and simulation time of the proposed simulation method, we designed currentmode buck and boost converters and fabricated them using a 0.18-μm highvoltage CMOS process. The comparison in the transient response and frequency characteristics among SPICE, the proposed program on a behavioral simulation tool which we named NSTVR (New Simulation Tool for Voltage Regulators) and experiments of fabricated IC chips showed good agreement, while NSTVR was more than 22 times faster in transient response and 85 times faster in frequency characteristics than SPICE in CPU