Driver circuit connected to a switched capacitor and method of operating same
OwnerKenneth Koch II, Mozammel Hossaininventors
Life of this patent
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Abstract
An integrated circuit driver includes an output stage having source drain paths of a PFET and NFET connected in series with each other across DC power supply terminals. A pair of CMOS inverters simultaneously responsive to a bilevel signal drive gate electrodes of the PFET and NFET. The inverters include resistors connected to NFET and PFET devices which function as voltage controlled switched capacitors respectively connected in shunt with gate electrodes of the output stage PFET and NFET. The inverters, resistors and capacitors prevent the output stage PFET and NFET from being on simultaneously.
Claims24
A circuit comprising an input terminal for connection to a voltage source having first and second levels and a transition between the levels, a driver including first and second opposite conductivity type transistors, each including a control electrode and a path switched on and off in response to a voltage applied to the control electrode being on opposite sides of a threshold, the first and second transistor paths being connected in series across opposite power supply terminals, an output terminal between the paths, circuitry connected between the first terminal and the control electrodes for causing the first and second transistor paths to be respectively (a) on and off while the voltage source has the first level and (b) off and on while the voltage source has the second level, and at least one switched capacitor connected between the first terminal and the driver for preventing the paths of the first and second transistors from being on simultaneously during transitions between the first and second levels.
A method of operating a driver including first and second opposite conductivity type transistors, each including a control electrode and a path between a pair of further electrodes controlled in response to a voltage applied to the control electrode, the paths of the first and second transistors being connected in series across opposite power supply terminals, an output terminal between the series connected paths, first and second switched capacitors respectively connected in shunt with the control electrodes, the method comprising:
- during a first interval:
- turning on and off the paths of the first and second transistors, respectively, while the second capacitor is charged and the first capacitor is switched off by applying (a) a first voltage having a first value to the control electrode of the first transistor, (b) the first voltage value across the second capacitor, and (c) a second voltage having the first value to the control electrode of the second transistor;
- during a second interval:
- turning off and on the paths of the first and second transistors, respectively, while the second capacitor is switched off and the first capacitor is charged by applying (a) the second value of the first voltage to the control electrode of the first transistor, (b) the first voltage value across the first capacitor, and (c) the second value of the second voltage to the control electrode of the second transistor;
- during an initial portion of a first transitional period between the first and second intervals:
- turning off the path of the first transistor while maintaining the path of the second transistor off by changing the first voltage from the first value toward the second value while the first capacitor remains turned off and the second capacitor is charged;
- during a second portion of the first transitional period turning on the path of the second transistor while maintaining the path of the first transistor off by changing the charge on the second capacitor so that there is a change in the value of the second voltage from the first value toward the second value;
- during an initial portion of a second transitional period between the second and first intervals:
- turning off the path of the second transistor while maintaining the path of the first transistor off by changing the second voltage from the second value toward the first value while the second capacitor remains turned off and the first capacitor is charged;
- and during a second portion of the second transitional period turning on the path of the first transistor while maintaining the path of the second transistor off by changing the charge on the first capacitor so that there is a change in the value of the first voltage from the second value toward the first value.
Dependencies are inferred from the claim text.