Class AB amplifier for use in semiconductor memory devices

An improved class AB amplifier, comprising:

• a first input node for receiving a first input signal;
• a second input node for receiving a second input signal;
• a push-pull input stage having a first current leg, a second current leg, a third current leg, and a fourth current leg, the push-pull input stage increasing the impedance between the second current leg and the third current leg when a second input signal is lower in potential than the first input signal, and increasing the impedance between the first current leg and the fourth current leg when the first input signal is lower in potential than the second input signal;
• a first current mirror coupled to a first power supply voltage, and having an input coupled to the second leg of the push-pull input stage, and an output coupled to a discharge node;
• a second current mirror coupled to a second power supply voltage, and having an input coupled to the fourth leg of the push-pull input stage, and an output coupled to a charge node;
• and
• an output driver having
• a pull-up circuit having a charging impedance path coupled between an output node and the first power supply voltage, the impedance of the charging impedance path being controlled by the potential at the charge node, and
• a pull-down circuit having a discharging impedance path coupled between the output node and the second power supply voltage, the impedance of the discharging impedance path being controlled by the potential at the discharge node.

An improved class AB amplifier, comprising:

• a first input node for receiving a first input signal;
• a second input node for receiving a second input signal;
• a push-pull input stage having a first current leg, a second current leg, a third current leg, and a fourth current leg, the push-pull input stage increasing the impedance between the second current leg and the third current leg when a second input signal is lower in potential than the first input signal, and increasing the impedance between the first current leg and the fourth current leg when the first input signal is lower in potential than the second input signal;
• a first current mirror coupled to a first power supply voltage and having an input coupled to the second leg of the push-pull input stage, and an output coupled to a discharge node;
• a second current mirror coupled to a second power supply voltage, and having an input coupled to the fourth leg of the push-pull input stage, and an output coupled to a charge node;
• and
• a discharge driver circuit coupled to the discharge node, the discharge driver circuit providing a low impedance path between the discharge node and the second power supply voltage in response to the potential at a discharge control node.

An improved class AB amplifier, comprising:

• a first input node for receiving a first input signal;
• a second input node for receiving a second input signal;
• a push-pull input stage having a first current leg, a second current leg, a third current leg, and a fourth current leg, the push-pull input stage increasing the impedance between the second current leg and the third current leg when a second input signal is lower in potential than the first input signal, and increasing the impedance between the first current leg and the fourth current leg when the first input signal is lower in potential than the second input signal;
• a first current mirror coupled to a first power supply voltage, and having an input coupled to the second leg of the push-pull input stage, and an output coupled to a discharge node;
• a second current mirror coupled to a second power supply voltage, and having an input coupled to the fourth leg of the push-pull input stage, and an output coupled to a charge node;
• and
• a charge driver circuit coupled to the charge node, the charge driver circuit providing a low impedance path between the charge node and the first power supply voltage in response to the potential at a charge control node.