1 . A circuit comprising: an amplifier having an input terminal and an output terminal; a capacitor having a first terminal and a second terminal, the first terminal of the capacitor coupled to the input terminal of the amplifier, the second terminal of the capacitor coupled to the output terminal of the amplifier; and diode circuitry having a first terminal and a second terminal, the first terminal of the diode circuitry coupled to the first terminal of the capacitor and the input terminal of the amplifier, the second terminal of the diode circuitry coupled to the second terminal of the capacitor and the output terminal of the amplifier.
2 . The circuit of claim 1 , wherein the diode circuitry includes: a resistor having a first terminal and a second terminal, the first terminal of the resistor coupled to the input terminal of the amplifier and the first terminal of the capacitor, the second terminal of the resistor coupled to the output terminal of the amplifier and the second terminal of the capacitor; a first diode having an anode terminal and a cathode terminal, the anode terminal of the first diode coupled to the first terminal of the resistor, the first terminal of the capacitor, and the input terminal of the amplifier, the cathode terminal of the first diode coupled to the second terminal of the resistor, the second terminal of the capacitor, and the output terminal of the amplifier; and a second diode having an anode terminal and a cathode terminal, the cathode terminal of the second diode coupled to the first terminal of the resistor, the first terminal of the capacitor, and the input terminal of the amplifier, the anode terminal of the second diode coupled to the second terminal of the resistor, the second terminal of the capacitor, and the output terminal of the amplifier.
3 . The circuit of claim 1 , wherein the diode circuitry includes: a first resistor having a first terminal and a second terminal; the first terminal of the first resistor coupled to the first terminal of the capacitor and the input terminal of the amplifier; a second resistor having a first terminal and a second terminal, the first terminal of the second resistor coupled to the second terminal of the first resistor, the second terminal of the second resistor coupled to the second terminal of the capacitor and the output terminal of the amplifier; and a transistor having a first current terminal, a second current terminal, and a control terminal, the first current terminal of the transistor coupled to the first terminal of the first resistor, the first terminal of the capacitor, and the input terminal of the amplifier, the second current terminal of the transistor coupled to the second terminal of the second resistor, the second terminal of the capacitor, and the output terminal of the amplifier, the control terminal of the transistor coupled to the second terminal of the first resistor and the first terminal of the second resistor.