Patent ID: 7769799

Claim:
A filter comprising: a first transistor being a p-channel transistor including a source, a drain coupled to a first switch, and a gate coupled to receive an input signal; a second transistor that is a current follower of the first transistor, the second transistor being an n-channel transistor including a drain coupled to the first switch, the first switch to couple the drain of the second transistor to the drain of the first transistor in response to a first control signal, the second transistor including a source coupled to a ground voltage reference, and a gate coupled to a second switch and to the first switch; a third transistor being an n-channel transistor including a drain, a gate coupled to the second switch, and a source coupled to the ground voltage reference; a fourth transistor coupled as a current follower of the third transistor, the fourth transistor being a p-channel transistor including a source coupled to the source of the first transistor, a gate, and a drain coupled to the gate of the fourth transistor and to the drain of the third transistor to generate an output signal at the drain of the third transistor; a fifth transistor coupled to the first transistor and the fourth transistor, the fourth transistor to mirror current of the first transistor and the fifth transistor to mirror current of the fourth transistor, the fifth transistor being a p-channel transistor including a source coupled to the source of the first transistor and the source of the fourth transistor, a drain coupled to the drain of the first transistor, and a gate coupled to the gate of the fourth transistor; and wherein the second switch is coupled between the gate of the second transistor and the gate of the third transistor to couple the second transistor to the third transistor in response to a second control signal to modulate the output signal based on current in the first transistor and the second transistor.