Low noise amplifier

A low noise amplifier, comprising:

• a preamplifier, receiving an input signal, and amplifying the input signal to generate a first signal, wherein the input signal and the first signal have the same phase;
• a plurality of first differential amplifiers, coupled to an output of the preamplifier, receiving the first signal and a first reference signal as a first input differential signal pair, and generating a first output differential signal pair according to the first input differential signal pair;
• a plurality of second differential amplifiers, receiving the input signal and a second reference signal as a second input differential signal pair, and generating a second output differential signal pair according to the second input differential signal pair;
• a signal adder, coupled to the first differential amplifiers and the second differential amplifiers, and configured to add up the first output differential signal pair and the second output differential signal pair to generate an addition result;
• and
• a load circuit, coupled to the signal adder, and generating a third output differential signal pair according to the addition result,
• wherein, a noise on the first signal and a noise on the input signal generated from a same noise source in the preamplifier have opposite phases.