A portable electronic device, comprising: an antenna unit comprising at least one pin (122, 122a, 122b); a processor comprising at least one signal control terminal (142, 142a, 142b) and configured to output at least one voltage control signal (VCTL, VCTL1, VCTL2); a circuit board; and at least one frequency switching circuit (180, 180a, 180b) disposed on the circuit board and electrically connected to the processor and the antenna unit, and the frequency switching circuit (180, 180a, 180b) comprising: a switch unit coupled with the pin (122, 122a, 122b); and an anti-noise unit coupled with the signal control terminal (142, 142a, 142b) and the switch unit, wherein the at least one voltage control signal (VCTL, VCTL1, VCTL2) is configured to switch a conducting state of the at least one frequency switching circuit (180, 180a, 180b), so as to adjust a grounding path of the antenna unit, thereby switching the operation frequency of the antenna unit, and wherein the switch unit is closer to the antenna unit than to the anti-noise unit, characterized in that the switch unit further comprises: a low pass filter, configured to filter out noise between the processor and the antenna unit; and a switch circuit, wherein the low pass filter comprises a first end coupled with the anti-noise unit and a second end, and the switch circuit comprises a first end coupled with the second end of the low pass filter, a second end coupled with the pin (122, 122a, 122b) and a third end coupled with a ground. an antenna unit comprising at least one pin (122, 122a, 122b); a processor comprising at least one signal control terminal (142, 142a, 142b) and configured to output at least one voltage control signal (VCTL, VCTL1, VCTL2); a circuit board; and at least one frequency switching circuit (180, 180a, 180b) disposed on the circuit board and electrically connected to the processor and the antenna unit, and the frequency switching circuit (180, 180a, 180b) comprising: a switch unit coupled with the pin (122, 122a, 122b); and an anti-noise unit coupled with the signal control terminal (142, 142a, 142b) and the switch unit, wherein the at least one voltage control signal (VCTL, VCTL1, VCTL2) is configured to switch a conducting state of the at least one frequency switching circuit (180, 180a, 180b), so as to adjust a grounding path of the antenna unit, thereby switching the operation frequency of the antenna unit, and wherein the switch unit is closer to the antenna unit than to the anti-noise unit, characterized in that the switch unit further comprises: a low pass filter, configured to filter out noise between the processor and the antenna unit; and a switch circuit, wherein the low pass filter comprises a first end coupled with the anti-noise unit and a second end, and the switch circuit comprises a first end coupled with the second end of the low pass filter, a second end coupled with the pin (122, 122a, 122b) and a third end coupled with a ground. a switch unit coupled with the pin (122, 122a, 122b); and an anti-noise unit coupled with the signal control terminal (142, 142a, 142b) and the switch unit, wherein the at least one voltage control signal (VCTL, VCTL1, VCTL2) is configured to switch a conducting state of the at least one frequency switching circuit (180, 180a, 180b), so as to adjust a grounding path of the antenna unit, thereby switching the operation frequency of the antenna unit, and wherein the switch unit is closer to the antenna unit than to the anti-noise unit, characterized in that the switch unit further comprises: a low pass filter, configured to filter out noise between the processor and the antenna unit; and a switch circuit, wherein the low pass filter comprises a first end coupled with the anti-noise unit and a second end, and the switch circuit comprises a first end coupled with the second end of the low pass filter, a second end coupled with the pin (122, 122a, 122b) and a third end coupled with a ground. a low pass filter, configured to filter out noise between the processor and the antenna unit; and a switch circuit, wherein the low pass filter comprises a first end coupled with the anti-noise unit and a second end, and the switch circuit comprises a first end coupled with the second end of the low pass filter, a second end coupled with the pin (122, 122a, 122b) and a third end coupled with a ground.