Patent ID: 7843272

Claim:
A low noise amplifier comprising: a cascode amplifier circuit that has input-stage and output-stage transistors connected in series to each other, and a load element, amplifies a signal at an input node connected with a control electrode of the input-stage transistor, and outputs the amplified signal from an output node of the output-stage transistor; an output circuit that amplifies a signal at the output node, and outputs the amplified signal to a first differential output terminal; a transformer having electro-magnetically coupled primary and secondary windings, the secondary winding having one end connected to an input terminal to which an input signal is applied, and another end connected to a second differential output terminal, the primary winding having one end connected to the input node and another end connected to the first differential output terminal; a feedback network that feeds back a signal at the first differential output terminal to the input terminal; a first phase compensation network connected between the control electrode of the input-stage transistor and the first differential output terminal; and a second phase compensation network connected between a control electrode of the output-stage transistor and the first differential output terminal.