Methods and apparatus to set a body bias of a resistor

An apparatus comprising:

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

An apparatus comprising:

• a first resistor having a first terminal and a bias terminal;
• a second resistor having a first terminal and a bias terminal;
• a third resistor having a first terminal and a second terminal, the first terminal of the third resistor coupled to the first terminal of the first resistor;
• first buffer circuitry having an input and an output, the output of the first buffer circuitry coupled to the bias terminal of the first resistor;
• a fourth resistor having a first terminal and a second terminal, the first terminal of the fourth resistor coupled to the second terminal of the third resistor and the input of the first buffer circuitry;
• a fifth resistor having a first terminal and a second terminal, the first terminal of the fifth resistor coupled to the first terminal of the second resistor;
• second buffer circuitry having an input and an output, the output of the second buffer circuitry coupled to the bias terminal of the second resistor;
• and
• a sixth resistor having a first terminal and a second terminal, the first terminal of the sixth resistor coupled to the second terminal of the fifth resistor and the input of the fifth resistor, the second terminal of the sixth resistor coupled to the second terminal of the fourth resistor.