Patent ID: 6608526
Filing Date: 2003-08-19
Classification: H03F

Abstract:
An apparatus, comprising:a transconductance amplifier that includes a first input that is coupled to a first node, a second input that is coupled to a mid-supply voltage, and an output that is coupled to an output terminal, wherein the transconductance amplifier is arranged to provide an output signal to the output terminal in response to an input signal at the first node; a bipolar transistor circuit that includes a first bipolar transistor and a second bipolar transistor, wherein the first bipolar transistor includes an emitter that is coupled to the first node, a base that is coupled to the mid-supply voltage, and a collector that is coupled to a second node, and wherein the second bipolar transistor includes an emitter that is coupled to the first node, a base that is coupled to the mid-supply voltage, and a collector that is coupled to a third node, wherein the first bipolar transistor is active when the input signal swings below the mid-supply voltage by a first predetermined amount, and the second bipolar transistor is active when the input signal swings above the mid-supply voltage by a second predetermined amount; a PMOS circuit that includes a p-type transistor, wherein the p-type transistor includes a drain that is coupled to the output terminal, a gate that is coupled to the second node, and a source that is coupled to a power supply voltage, wherein the PMOS circuit is activated when the first bipolar transistor is active; and an NMOS circuit that includes an n-type transistor, wherein the n-type transistor includes a drain that is coupled to the output terminal, a gate that is coupled to the third node, and a source that is coupled to a circuit ground, wherein the NMOS circuit is activated when the second bipolar transistor is active.