SIGNAL ISOLATION APPARATUS AND SIGNAL ISOLATION METHOD

This application relates to the field of semiconductor devices, and discloses a signal isolation apparatus. The signal isolation apparatus includes: a metal oxide semiconductor (MOS) device, where the MOS device is formed on a P-type substrate and has an N well; an N-type substrate contact, where the N-type substrate contact is formed in the N well and connected to supply voltage; a P-type substrate contact, where the P-type substrate contact is formed on the P-type substrate and connected to grounding voltage; and an isolation ring at least partially surrounding the N well, where a doping density of an ion implanted into the isolation ring is lower than a doping density of an ion implanted into the N well or a doping density of an ion implanted into the P-type substrate. The N well is surrounded by the isolation ring, and a density of the isolation ring is lower than a density of the N well or a density of the P-type substrate. Therefore, a junction capacitance of a P-N junction formed between the N well and the P-type substrate is decreased, and an equivalent capacitive reactance of the P-N junction when a noise signal passes through the P-N junction is increased, thereby improving an effect of isolating the noise signal.