Apparatuses and methods for a voltage level shifting
View Patent ↗Level shifting circuits and a related method are disclosed herein. An embodiment of the present invention includes a voltage level shifter, comprising a first pull up transistor coupled to a high voltage signal and a first pull down transistor coupled between the first pull up transistor and a low voltage signal and controlled by an input signal. The voltage level shifter further includes a first bias transistor serially coupled between the first pull up transistor and the first bias transistor. A gate of the first bias transistor is coupled with a bias voltage signal. The voltage level shifter further includes a first additional pull up path coupled with the high voltage signal and a first node between the first pull up transistor and the first pull down transistor, and an output signal associated with the first node. The output signal is a level shifted voltage responsive to the input signal.
1. A method for shifting an input voltage level to a different output voltage level, the method comprising:
pulling down a voltage on an output node of a level shifter in a relatively faster manner than pulling up a voltage on an output node responsive to an input signal;
pulling up a voltage on the output node with at least both of a pull up transistor and an additional pull up path responsive to the input signal;
turning off the additional pull up path as a voltage on the output node increases above a threshold level, wherein turning off the additional pull up path is accomplished through a direct connection between the output node and a gate of a control transistor of the additional pull up path; and
generating a voltage level shifted output on the output node that is a voltage level different than the input signal.
2. The method of claim 1 , wherein generating a voltage level shifted output includes resulting in a voltage level shifted output with a voltage swing that is different than a voltage swing of the input signal.
3. The method of claim 1 , wherein generating a voltage level shifted output includes resulting in a voltage level shifted output with a voltage swing that is the same as a voltage swing of the input signal.
4. The method of claim 1 , wherein generating a voltage level shifted output includes resulting in a voltage level shifted output with a voltage swing that includes at least one negative voltage.
5. The method of claim 1 , wherein pulling down a voltage on an output node of a level shifter in a relatively faster manner than pulling up a voltage on an output node comprises:
deactivating a pull up transistor with a relatively small gate width and a large gate length relative to a gate of a pull down transistor; and
activating the pull down transistor.
6. A level shifting circuit, comprising:
a first node coupling a first pull up circuit and a first pull down circuit, wherein:
the first pull down circuit is responsive to an input signal; and
the first pull up circuit is further coupled to a high voltage signal and the first pull down circuit is coupled to a low voltage signal;
a first additional pull up path including a first transistor serially coupled with a second device configured as a diode and coupled with the first node, the second device configured to control the activation of the first additional pull up path during a transition from low to high on the first node; and
an output signal associated with the first node, wherein the output signal is configured to generate a level shifted voltage in response to the input signal.
7. The level shifting circuit of claim 6 , wherein the second device configured as a diode includes a second transistor coupled to the first node, wherein a gate of the second transistor is also directly coupled to the first node.