Electricity: power supply or regulation systems – Output level responsive – Using a three or more terminal semiconductive device as the...
Reexamination Certificate
2000-04-20
2001-08-07
Berhane, Adolf Deneke (Department: 2838)
Electricity: power supply or regulation systems
Output level responsive
Using a three or more terminal semiconductive device as the...
Reexamination Certificate
active
06271651
ABSTRACT:
BACKGROUND
The present invention relates to voltage regulators.
Voltage regulators, such as DC-to-DC converters, are used to provide stable voltage sources for electronic systems. Efficient DC-to-DC converters are particularly needed for battery management in low power devices, such as laptop computers and mobile phones. Switching voltage regulators (or simply “switching regulators”) are known to be an efficient type of DC-to-DC converter. A switching regulator generates an output voltage by converting an input DC voltage into a high frequency voltage, and filtering the high frequency voltage to generate the output DC voltage.
Conventional switching regulators include two switches. One switch is used to alternately couple and decouple an unregulated input DC voltage source, such as a battery, to a load, such as an integrated circuit. The other switch is used to alternately couple and decouple the load to ground. An output filter, typically including an inductor and an output capacitor, is coupled between the input voltage source and the load to filter the output of the switches and produce the output DC voltage. In low power application, there is typically also a discontinuous mode of operation where both switches are open, so that the output filter is not actively driven. In this case, the input and output terminals of the filter will resonate at a high frequency until equilibrium is reached. The high frequency component in the inductor current and the filter input voltage can conduct and radiate to nearby noise sensitive circuits, causing degradation in the performance of those circuits.
SUMMARY
In one aspect, the invention is directed to a switching cell having first, second, third and fourth terminals. The switching cell includes an inductor disposed between a first node and the third terminal, a power switch disposed between the first terminal and the first node, a rectifier switch disposed between the first node and a second node, the second node coupling the second and fourth terminals, and a shorting switch connected in parallel with the inductor.
Implementations of the invention may include the following. The power switch may be a transistor. The rectifier switch may be a transistor or a diode. The shorting switch may be a transistor, a variable current source or a variable resistor. The switching cell may include a resistor connected in series with the shorting switch or a current source connected in series with the shorting switch.
In another aspect, the invention is directed to a switching regulator having first, second, third and fourth terminals. The switching regulator includes a power switch disposed between the first terminal and a first node, a rectifier switch disposed between the first node and a second node, the second node coupling the second and fourth terminals, a filter including an inductor and a capacitor, the inductor being disposed between the first node and the third terminal, and the capacitor being disposed between the third and fourth terminals, a shorting switch connected in parallel with the inductor, and a controller operable in a plurality of modes to open and close the power switch, the rectifier switch and the shorting switch.
Implementations of the invention may include the following. The plurality of modes may include a first mode in which the shorting switch and rectifier switch are open and the power switch is closed and a second mode in which the shorting switch and the power switch are open and the rectifier switch is closed. The controller may be configured to alternate between the first and second modes in response to a substantially constant load. The plurality of modes may include a third mode in which the power switch and the shorting switch are closed and the rectifier switch is open, and wherein the controller is configured to switch to the third mode to respond to a positive-going load step. The controller may be configured to alternately open and close the shorting switch to control the average amount of current flowing through the shorting switch. The controller may be configured to modulate an impedance of the shorting switch to vary the amount of current flowing through the shorting switch. The plurality of modes may include a fourth mode in which the rectifier switch and the shorting switch are closed and the power switch is open. The controller may be configured to switch to the fourth mode to respond to a negative-going load step. The controller may be configured to alternately open and close the shorting switch to control the average amount of current flowing through the shorting switch. The controller may be configured to modulate an impedance of the shorting switch to vary the amount of current flowing through the shorting switch. The plurality of modes may include a fifth mode in which the power switch and the rectifier switch are open and the shorting switch is closed, and wherein the controller is configured to switch to the fifth mode when current passing through the inductor reaches zero.
The first terminal may be coupled to a voltage source, the third terminal may be coupled to a load, and the second and fourth terminals may be coupled to electrical ground, such that the switching regulator is part of a buck converter circuit. The third terminal may be coupled to a voltage source, the first terminal may be coupled to a load, and the second and fourth terminals may be coupled to electrical ground, such that the switching regulator is part of a boost converter circuit. The first terminal may be coupled to a voltage source, the fourth terminal may be coupled to a load, and the second and third terminals may be coupled to electrical ground, such that the switching regulator is part of a buck-boost converter circuit. The switching regulator may include a plurality of shorting switches connected in parallel with the inductor.
The power switch, the rectifier switch and the shorting switch may be fabricated on different chips, or alternatively, on a single chip. Any or all of the switches may be implemented as discrete components. The switching regulator may include a resistor connected in series with the shorting switch. The shorting switch and the resistor switch may be fabricated on different chips, or alternatively, on a single chip. The inductor may be one of a plurality of inductors disposed between the first node and the third terminal. There may be individually controlled shorting switches in parallel with each inductor.
In another aspect, the invention is directed to an electronic device. The electronic device includes a switching cell having a power switch, a rectifier switch, a shorting switch, an inductor and four terminals, wherein one of the four terminals is to be connected to a voltage source, another of the four terminals is to be connected to a load, and the remaining two terminals are to be connected to ground, a voltage source, a load, and a controller operable in a plurality of modes to open and close the power switch, the rectifier switch and the shorting switch.
Advantages that can be seen in implementations of the invention include one or more of the following. The invention provides a shorting switch connected in parallel with the inductor. Driving a shorting switch in conjunction with the power switch and the rectifier switch: (a) provides an inductor-bypass that can improve the transient response of a circuit; and (b) eliminates the high frequency ringing during discontinuous mode. The invention allows for the use of an event-based simulation engine rather than a time-stepped simulation engine, which can significantly reduce the simulation time of the circuit under test during the design process.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features and advantages of the invention will become apparent from the description, the drawings, and the claims.
REFERENCES:
patent: 5422562 (1995-06-01), Mammano et al.
patent: 5479089 (1995-12-01), Lee
patent: 6051963 (2000-04-01), Eagar
Stratakos Anthony J.
Zuniga Marco A.
Berhane Adolf Deneke
Fish & Richardson P.C.
Volterra Semiconductor Corporation
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