Digital level shifter with reduced power dissipation and false transmission blocking
First Claim
1. A digital level shift circuit for providing level shifted output signals in response to input pulses defined by a first transition between a first voltage and a second voltage, and a second transition between the second voltage and the first voltage, the circuit comprising:
- a level shifting device that is turned on in response to the first input transition to make an output transition; and
feedback circuitry that obtains a feedback signal indicating that the level shifting device has made the output transition and that turns off the level shifting device during the interval between the first and second input transitions in response to the feedback signal.
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Accused Products
Abstract
A circuit including a level shifting device such as a high voltage MOS device which is turned on to make an output transition, and feedback circuitry which responds to the transition to turn off the level shifting device. A circuit including two n-channel devices and two p-channel devices can sense when current greater than a threshold flows through both devices of one channel type to prevent false output transitions due to rapid changes in offset voltage, or both features can be provided. Level shifting devices can also be connected so none of the devices receives its acknowledge signal from the device to which it provides an acknowledge signal to avoid a standoff between two devices. For each device, the feedback circuitry can distinguish acknowledge signals so a device that stops transmitting in response to a signal that was not an acknowledge signal cam be restarted.
9 Citations
21 Claims
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1. A digital level shift circuit for providing level shifted output signals in response to input pulses defined by a first transition between a first voltage and a second voltage, and a second transition between the second voltage and the first voltage, the circuit comprising:
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a level shifting device that is turned on in response to the first input transition to make an output transition; and
feedback circuitry that obtains a feedback signal indicating that the level shifting device has made the output transition and that turns off the level shifting device during the interval between the first and second input transitions in response to the feedback signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A digital level shift circuit for providing level shifted output signals, the circuit comprising:
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first and second n-channel devices that make output transitions in response to turn-on signals;
each turn-on signal towing on one of the n-channel devices to make an output transition;
the first and second n-channel devices not receiving concurrent turn-on signals;
first and second p-channel devices that make output transitions in response to turn-on signals;
each turn-on signal turning on one of the p-channel devices to make an output transition;
the first and second p-channel devices not receiving concurrent turn-on signals; and
sense/prevent circuitry that senses when current greater than a threshold flows through both of the first and second devices of one channel type and, in response, prevents output transitions from being made. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A digital level shift circuit for providing level shifted output signals, the circuit comprising:
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first and second n-channel devices that make output transitions in response to turn-on signals;
each turn-on signal turning on one of the n-channel devices to make an output transition;
the first and second n-channel devices not receiving concurrent turn-on signals;
first and second p-channel devices that make output transitions in response to turn-on signals;
each turn-on signal turning on one of the p-channel devices to make an output transition;
the first and second p-channel devices not receiving concurrent turn-on signals; and
control circuitry that controls when each device receives its turn-on signals;
the control circuitry including;
feedback circuitry that obtains a feedback signal for each device indicating that the device has made an output transition and that stops the device'"'"'s turn-on signal in response to the feedback signal; and
sense/prevent circuitry that senses when current above a threshold flows through both of the first and second devices of one channel type and, in response, prevents output transitions from being made. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
feedback detection circuitry for each device to distinguish feedback signals from transmissions.
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21. The digital level shift circuit of claim 17 in which the feedback detection circuitry for a device includes an AND gate that determines whether a signal from another device was received when the other device was receiving a feedback signal in response to a transmission.
Specification