A signal processing circuit with noise cancellation includes an impedance matching unit and a transconductance stage. The impedance matching unit is disposed at a first path, and arranged to provide input impedance matching, wherein the impedance matching unit is a bilateral element, and the first path is coupled between a signal input port and a signal output port. The transconductance stage is disposed at a second path, and arranged to guide circuit introduced noise to the signal output port for noise cancellation at the signal output port, wherein the second path is coupled between the signal input port and the signal output port.