Cascode Amplifier with Improved High Frequency Linearity

A cascode amplifier, comprising:

• an amplifier transistor having a first terminal receiving a first power supply voltage, a second terminal, and a control terminal receiving an input signal;
• a cascode transistor having a first terminal coupled to the second terminal of the amplifier transistor, a second terminal coupled to an output terminal;
• and a control terminal receiving a bias voltage;
• and
• a current injection circuit having an input receiving the input signal, and first and second outputs coupled to the first and second terminals of the cascode transistor, respectively, the current injection circuit configured to present out-of-phase currents from its first and second outputs responsive to the input signal.

A method, comprising:

• receiving an input signal at an amplifier transistor in a cascode amplifier, the cascode amplifier further including a cascode transistor coupled to the input transistor;
• responsive to the input signal, generating out-of-phase injection currents from first and second outputs of a current injection circuit;
• applying the out-of-phase injection currents to first and second current terminals of the cascode transistor;
• and
• generating an output signal from an output of the cascode amplifier responsive to the input signal.