Amplifier and receiving circuit, semiconductor apparatus, and semiconductor system using the same

An amplifier comprising:

• an amplification circuit configured to change voltage levels of a first amplification node and a second amplification node based on a first input signal and a second input signal;
• a first transistor having a source coupled to a first supply voltage terminal and a drain coupled to the second amplification node;
• a first resistor circuit coupled between a gate of the first transistor and the second amplification node, and having a resistance value which is changed based on a first gain control signal
• a second transistor having a source coupled to the first supply voltage terminal and a drain coupled to the first amplification node;
• a second resistor circuit coupled between a gate of the third transistor and the first amplification node, and having a resistance value which is changed based on the first gain control signal
• an equalization circuit configured to change the voltage level of the second amplification node based on the voltage level of the first amplification node and configured to change the voltage level of the first amplification node based on the voltage level of the second amplification node;
• and
• an output circuit configured to generate an output signal based on the voltage levels of the first and second amplification nodes.