Low noise amplifier and differential amplifier with variable gain mode

A differential amplifier having a variable gain mode, the differential amplifier comprising:

• a first selection unit comprising a first selection cell, a second selection cell, and a third selection cell for selectively transmitting a first input signal to an amplification unit to select one of the first to third selection cells in accordance with the magnitude of the first input signal;
• a second selection unit comprising a fourth selection cell, a fifth selection cell, and a sixth selection cell for selectively transmitting a second input signal to the amplification unit to select one of the fourth to sixth selection cells in accordance with the magnitude of the second input signal;
• a first amplification unit comprising a first amplification cell for amplifying a signal applied from the first selection cell to a first gain mode and outputting, a second amplification cell for amplifying a signal applied from the second selection cell to a second gain and outputting, and a third amplification cell for amplifying a signal applied from the third selection cell to a third gain mode and outputting;
• and
• a second amplification unit comprising a fourth amplification cell for amplifying a signal applied from the fourth selection cell to a fourth gain mode and outputting, a fifth amplification cell for amplifying a signal applied from the fifth selection cell to a fifth gain and outputting, and a sixth amplification cell for amplifying a signal applied from the sixth selection cell to a sixth gain mode and outputting.