Abstract ▼ AI-Helper

For decades, the quartz crystal has been used for a high quality oscillators. Applications, such as, medical equipments, precise measurement systems and portable wireless communication devices have increasingly demanded a precise frequency references, therefore, they imposed the tight frequency stab...

For decades, the quartz crystal has been used for a high quality oscillators. Applications, such as, medical equipments, precise measurement systems and portable wireless communication devices have increasingly demanded a precise frequency references, therefore, they imposed the tight frequency stabilities on the TCXO(Temperature Compensated Crystal Oscillator). This paper presents the theory of a temperature compensation method and the design of the TCXO having the high frequency stability and a small size. The TCXO is implemented in a single chip with an external quartz crystal. Because a temperature sensor and a variable capacitor need a large area, a careful design & layout are needed to achieve the economical size of the chip. And a temperature compensation method in an analog domain is introduced for the high frequency stability. The proposed circuit have a frequency stability that is less than ±0.2ppm for a supply power variation from 2.7 to 3.3V, is less than ±1.5ppm for a ambient temperature variation from -30 to 85℃, and is less than ±0.5ppm for a output load variation from 0 to 50pF. It is fabricated in a 0.5um CMOS process. The die area is 1.6mm * 1.4mm (2.24 ㎟) which is a small chip size compared to other TCXO.

Keyword