1. Field of the Invention
The invention relates generally to a sensor system and, more particularly, to a fully on-chip temperature, process, and voltage sensor system capable of operating in a low voltage environment.
2. Description of Related Art
With the advance of technology, electronic products related to wireless sensor are continuously applied into our daily life. However, electronic products related to wireless sensor all face the problems about how to reduce power consumption effectively. Electronic products can have prolonged lifetime of batteries only by reducing their power consumption. Therefore, how to design low power consumption circuits is getting more and more important.
In order to achieve low power consumption, circuits are usually operated in a voltage close to a sub-threshold voltage. However, when circuits are operated in an extremely low voltage, they are very sensitive to the variation of temperature, process and voltage, and may cause data error easily. Further, semiconductor manufactures are constantly facing new variation problems, such as circuit delay in capacity connection, signal integrity and reliability. Besides, variation noise in the operating environment also makes operating frequency and power consumption increase, resulting in an even greater variation in circuit performance.
In the known wireless sensor, temperature sensing can be accomplished by using analog-to-digital converters. However, the use of analog-to-digital converter inevitably makes noise and power consumption increase. Therefore, it is desirable to provide an improved sensor system to mitigate and/or obviate the aforementioned problems.