a mixer in a smaller signal differential model includes a load circuit , a switch quad , and a transconductor . the switch quad further including a first current path and a second current path is coupled to the load circuit . the connecting node of the switch quad and the load circuit is a differential - output terminal . the transconductor further includes a first resistor , a first operational amplifier , a second operational amplifier , a first current mirror , and a second current mirror . the resistor is coupled between two first input terminals of the first operational amplifier and the second operational amplifier . a current control terminal of the first current mirror is coupled to the first input terminal of the first operational amplifier , and a current mirroring terminal of the first current mirror is coupled to the first current path . a current control terminal of the second current mirror is coupled to the first input terminal of the second operational amplifier , and a current mirroring terminal of the second current mirror is coupled to the second current path . a differential voltage is applied between two second input terminals of the first operational amplifier and the second operational amplifier .