Current driver circuits for reducing substrate noise and methods of operating the same

A current driver circuit, comprising:

• a pull-down switch unit that is coupled between a node and a first reference potential and is operative to switch between an on-state and an off-state responsive to an input signal;
• and
• a pull-up switch unit that is coupled between the node and a second reference potential and is operative to switch between an on-state and an off-state, complementary to the pull-down switch unit, a turn-on speed of the pull-up switch unit being slower than that of the pull-down switch unit, and a turn-off speed of the pull-up switch unit being faster than that of the pull-down switch unit;
• wherein the pull-up switch unit comprises a PMOS transistor and an NMOS transistor coupled in series between the node and the second reference potential.

A current driver circuit, comprising:

• a first pull-down switch unit that is coupled between a first node and a first reference potential and is operative to switch between an on-state and an off-state responsive to an input signal;
• a first pull-up switch unit that is coupled between the first node and a second reference potential and is operative to switch between an on-state and an off-state, complementary to the first pull-down switch unit, a turn-on speed of the first pull-up switch unit being slower than that of the first pull-down switch unit, and a turn-off speed of the first pull-up switch unit being faster than that of the first pull-down switch unit;
• a second pull-down switch unit that is coupled between a second node and the first reference potential and is operative to switch between an on-state and an off-state responsive to a logical complement of the input signal;
• a second pull-up switch unit that is coupled between the second node and the second reference potential and is operative to switch between an on-state and an off-state, complementary to the second pull-down switch unit, a turn-on speed of the second pull-up switch unit being slower than that of the second pull-down switch unit, and a turn-off speed of the second pull-up switch unit being faster than that of the second pull-down switch unit;
• a current source circuit that is coupled between the first node and an output terminal and is responsive to a reference signal;
• and
• a current supply circuit that is coupled between the second reference potential and the second node and is responsive to the reference signal.

A method of operating a current driver circuit, comprising:

• switching a pull-down switch unit between an on-state and an off-state responsive to an input signal;
• and
• switching a pull-up switch unit between an on-state and an off-state, complementary to the pull-down switch unit, such that a turn-on speed of the pull-up switch unit is slower than that of the pull-down switch unit, and a turn-off speed of the pull-up switch unit being is faster than that of the pull-down switch unit;
• wherein the pull-up switch unit comprises a PMOS transistor and an NMOS transistor coupled in series.

A charge pump, comprising:

• a down current pull-down switch unit that is coupled between a down node and a first reference potential and is operative to switch between an on-state and an off-state responsive to a down input signal;
• a down current pull-up switch unit that is coupled between the down node and a second reference potential and is operative to switch between an on-state and an off-state, complementary to the down current pull-down switch unit, responsive to the down input signal, a turn-on speed of the down current pull-up switch unit being slower than that of the down current pull-down switch unit, and a turn-off speed of the down current pull-up switch unit being faster than that of the down current pull-down switch unit;
• an up current pull-up switch unit that is coupled between an up node and the first reference potential and is operative to switch between an on-state and an off-state responsive to a logical complement of an up input signal;
• an up current pull-down switch unit that is coupled between the up node and the second reference potential and is operative to switch between an on-state and an off-state, complementary to the up current pull-up switch unit, responsive to the up input signal, a turn-on speed of the up current pull-down switch unit being slower than that of the up current pull-up switch unit, and a turn-off speed of the up current pull-down switch unit being faster than that of the up current pull-up switch unit;
• a down current source circuit that is coupled between the down node and an output terminal and is responsive to a down reference signal;
• and
• an up current source circuit that is coupled between the up node and the output terminal and is responsive to an up reference signal.