Patent ID: 8076969

Claim:
A high pass filter having a cutoff frequency, the high pass filter comprising: a first amplifier to receive an input signal, the high pass filter to attenuate low frequency signals of the input signal that are below the cutoff frequency; a second amplifier to provide an output signal, the output signal comprising only high frequency signals of the input signal that are above the cutoff frequency; a capacitive element coupled in between the first amplifier and the second amplifier; and a variable frequency module communicating with the capacitive element and including a plurality of resistive paths of the high pass filter, wherein each resistive path corresponds to a different cutoff frequency for the high pass filter, wherein the variable frequency module comprises i) a first transistor having a first source/drain region formed in a first well region and ii) a first diode region formed between the first source/drain region and the first well region, wherein a first node of the first diode region is connected to the first source/drain region and a reference node, wherein a second node of the first diode region is connected to the reference node, and wherein the variable frequency module is configured to prevent any leakage current from draining the capacitive element.