Variable-Gain Image-Reject Low-Noise Amplifier

A receiver comprising at least one variable-gain amplifier, each variable-gain amplifier comprising:

• an intermediate node operative to receive an electric current from a current source;
• a common-emitter amplifier having a collector electrically connected to the intermediate node;
• a first common-base amplifier having an emitter electrically connected to the intermediate node and a collector electrically connected to an output node;
• a base-degenerated amplifier having an emitter electrically connected to the intermediate node and a collector electrically connected to the output node;
• a second common-base amplifier having an emitter electrically connected to the intermediate node and a collector electrically connected to small-signal ground;
• wherein the intermediate node is operative to direct the electric current to the first common-base amplifier, thereby causing the variable-gain amplifier to operate in a first mode;
• and
• wherein the intermediate node is operative to direct the electric current to the base-degenerated amplifier and the second common-base amplifier, thereby causing the variable-gain amplifier to operate in a second mode.

A design structure embodied in a machine readable medium, the design structure comprising a variable-gain amplifier, the variable-gain amplifier comprising:

• an intermediate node operative to receive an electric current from a current source;
• a common-emitter amplifier having a collector electrically connected to the intermediate node;
• a first common-base amplifier having an emitter electrically connected to the intermediate node and a collector electrically connected to an output node;
• a base-degenerated amplifier having an emitter electrically connected to the intermediate node and a collector electrically connected to the output node;
• a second common-base amplifier having an emitter electrically connected to the intermediate node and a collector electrically connected to small-signal ground;
• wherein the intermediate node is operative to direct the electric current to the first common-base amplifier, thereby causing the variable-gain amplifier to operate in a first mode;
• and
• wherein the intermediate node is operative to direct the electric current to the base-degenerated amplifier and the second common-base amplifier, thereby causing the variable-gain amplifier to operate in a second mode.

A method of operating a variable-gain amplifier comprising the steps of:

• receiving an electric current at an intermediate node;
• determining one of a plurality of modes in which the variable-gain amplifier should operate;
• responsive to a determination that the variable-gain amplifier should operate in a first mode, directing the electric current from the intermediate node to a first common-base amplifier, the first common-base amplifier having an emitter electrically connected to the intermediate node and a collector electrically connected to an output node;
• responsive to a determination that the variable-gain amplifier should operate in a second mode, directing the electric current from the intermediate node to a base-degenerated amplifier and a second common-base amplifier, the base-degenerated amplifier having an emitter electrically connected to the intermediate node and a collector electrically connected to the output node and the second common-base amplifier having an emitter electrically connected to the intermediate node and a collector electrically connected to small-signal ground.