Patent ID: 9059675
Filing Date: 2015-06-16
Classification: H03F,H03H

Abstract:
1. A circuit comprising: an operational amplifier having an output connected to a negative input of the operational amplifier, the operational amplifier configured to provide at the output a filtered version of an input signal; a first capacitor to receive the input signal; a second capacitor connected in series with the first capacitor, the second capacitor to provide a first signal to a positive input of the operational amplifier; a first resistor connected in series with the first capacitor, the first resistor to provide a second signal to the negative input of the operational amplifier; a second resistor to receive the input signal; a third resistor connected in series with the second resistor, the third resistor to provide a third signal to the positive input of the operational amplifier; and a third capacitor connected in series with the second resistor, the third capacitor to provide a fourth signal to the negative input of the operational amplifier, wherein a capacitance value of the first capacitor, a capacitance value of the second capacitor, a resistance value of the second resistor, and a resistance value of the third resistor determine an attenuation frequency of the input signal, and wherein a capacitance value of the third capacitor and a resistance value of the first resistor determine amounts of attenuation in the input signal at and above the attenuation frequency, and an amount of attenuation at the frequency is greater than an amount of attenuation above the frequency.