Methods, systems, and apparatus for coupling power amplifier input signals

A circuit comprising:

• a first transistor including a first gate terminal, a first drain terminal, and a first source terminal;
• a first resistor including a first resistor terminal and a second resistor terminal, wherein the first resistor terminal is coupled to the first drain terminal;
• a second transistor including a second gate terminal, a second drain terminal, and a second source terminal;
• a second resistor including a third resistor terminal and a fourth resistor terminal, wherein the third resistor terminal is coupled to the second drain terminal and the fourth resistor terminal is coupled to the second resistor terminal at an output common mode node;
• a third transistor including a third gate terminal, a third drain terminal, and a third source terminal, wherein the third drain terminal is coupled to the first resistor terminal and to the first drain terminal;
• and
• a fourth transistor including a fourth gate terminal, a fourth drain terminal, and a fourth source terminal, wherein the fourth drain terminal is coupled to the third resistor terminal and to the second drain terminal, and the fourth gate terminal is coupled to the third gate terminal.

An apparatus comprising:

• signal processing circuitry including a first data output and a second data output;
• pre-amplifier circuitry including:
• a first amplifier including a first input, a second input, a first output, and a second output, wherein the first input is coupled to receive the first data output and the second input is coupled to receive the second data output;
• a second amplifier including a third input, a fourth input, a feedback input, a differential output that includes a third output and a fourth output, wherein the third input (234a) is coupled to the first output and the fourth input is coupled to the second output;
• a third amplifier including a fifth input, a sixth input, and a feedback output, the feedback output coupled to the feedback input;
• and
• averaging resistors coupled to the third and fourth outputs and coupled to the fifth input;
• a power amplifier including a seventh input and an eighth input, the seventh input coupled to the third output and the eighth input coupled to the fourth output;
• and
• an antenna coupled to an output of the power amplifier.