Methods and apparatus to amplify signals using amplifier circuitry

An apparatus comprising:

• transconductance circuitry having an input and an output;
• a first capacitor having a terminal;
• an amplifier having an input and an output, the input of the amplifier coupled to the output of the transconductance circuitry and the terminal of the first capacitor;
• a first resistor having a first terminal and a second terminal, the first terminal of the first resistor coupled to the output of the amplifier;
• a second resistor having a terminal;
• a third resistor having a first terminal and a second terminal, the first terminal of the third resistor coupled to the input of the transconductance circuitry, the second terminal of the first resistor, and the terminal of the second resistor;
• and
• a second capacitor having a terminal coupled to the second terminal of the third resistor.

An apparatus comprising:

• transconductance circuitry having an input and an output;
• an amplifier having an input and an output, the input of the amplifier coupled to the output of the transconductance circuitry;
• a first resistor having a first terminal and a second terminal;
• a first capacitor having a first terminal and a second terminal, the first terminal of the first capacitor coupled to the output of the amplifier and the first terminal of the first resistor;
• a second resistor having a first terminal and a second terminal, the first terminal of the second resistor coupled to the input of the transconductance circuitry, the second terminal of the first resistor, and the second terminal of the first capacitor;
• and
• a second capacitor having a terminal coupled to the second terminal of the second resistor.