Semiconductor device

A semiconductor device comprising a variable gain amplifier circuit which receives first and second control signals and amplifies an input signal by a gain according to the first control signal,

• the variable gain amplifier circuit including:
• an output node for outputting an amplified input signal;
• a plurality of amplifiers which are coupled in parallel with each other between the output node and a first reference node to which a first reference potential is provided and selectively assume an operating state in accordance with the first control signal;
• and
• a detection circuit which detects the input signal, outputs a detection signal according to a magnitude of the detected input signal to each of the amplifiers if the second control signal is asserted, and outputs a signal of a fixed magnitude to each of the amplifiers if the second control signal is deasserted,
• each of the amplifiers including:
• a first transistor which receives, at its control electrode, the input signal or a signal proportional to the input signal;
• a second transistor which is series-coupled to the first transistor between the first reference node and the output node;
• and
• a bias circuit which applies a DC voltage according to the detection signal or the signal of the fixed magnitude to a control electrode of the second transistor.