Rf power detection circuit with insensitivity to process, temperature and load impedance variation

A circuit comprising:

• a multiplier circuit including a mixer configured to multiply a first differential input signal and a second differential input signal,
• wherein the mixer comprises a plurality of transistors including control terminals, and
• wherein the control terminals of the plurality of transistors receive a bias signal and the first differential input signal;
• a first differential amplifier configured to receive an output of the mixer;
• a bias circuit configured to generate the bias signal, the bias signal generated by the bias circuit based on i) a voltage threshold of one of the plurality of transistors and ii) a product of constant reference current and a bias resistance,
• wherein the bias circuit includes:
• a current source configured to generate the constant reference current;
• a bias resistance having the bias resistance and including one end in communication with the current source;
• and
• a first transistor including a first terminal and a control terminal in communication with one end of the bias resistance,
• wherein the bias signal is generated at a node between the bias resistance and the current source;
• and
• a common mode feedback amplifier connected to an output of the first differential amplifier and having a common mode input connected to the bias circuit.