Home>>Core Technology>>CMOS Current automatic control crystal oscillator |
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CMOS Current automatic control crystal oscillator |
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The oscillator is a necessary part among most of the electronic consumers. The crystal oscillator with the advantages of high accuracy and high frequency stablity takes a very inmportant role in the electronic technology area. Especially with the rapid development of IT industry, the crystal oscillator is full of vitality in the market.
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The crystal oscillator, as standered frequncy source or pulse signal source, providing frequency reference, applied in the communication system, mobile phone system, GPS, navigation, remote control, aerospace, high speed computer, precision measuring instrument and civil electronic consumer products, can not be sustituded by other types of oscillators．The crystal oscillator produces oscillation depending on the crystal piezoelectric property, resouce activity and passive reactance network without the additional input signal.
Under the CMOS artwork condition, there are two common-use oscillators: Pierce oscillator and Colpittis oscillator. The two both apply the Bikini Oscillation thoery. Pierce oscillator must connect the two ends of the crystal, but one end crystal connection is asked in the most of the circuit application. Colpittis oscillator has its advantage in the application. Moreover, the harmonics property of the Colpittis oscillator is better than Pierce oscillator. Yet in oscillation establishment, Colpittis oscillator can not easily be started up. It needs more time to start up and cosumes more power.
To overcome the defeciencies of current oscillators, MCDevices.Let invented a CMOS Current automatic control crystal oscillator, which has been aworded an invention patent certification by the State intellectual property office of the People’s Republic of China. The patent number of the invention is : ZL200810216346.X CMOS Current automatic control crystal oscillator, aplying the way of amplitude detecting and Automatic gain control , makes the oscillating circuit set up oscillation with large current when it starts up, adjust the biased current quikly, maintain the oscillator circuit in the state of the minimum current, shorten the start-up effectively, and decrease the circuit power consumption significantly.
Compared with Colpittis oscillator, under the same oscillation amplitude, the time needed for CMOS Current automatic control crystal oscillator start –up shortens by 1/2; circuit power consumption decreases by 1/2. What’s more, the oscillating biased current is the largest initially, therefor the reliability of start-up is guaranteed stongly. The prominent characteristic of CMOS Current automatic control crystal oscillator is that under different operationg voltage, different crystal oscillation and producting artwork deviation, circuit consumption, with automatic adjusting, becomes the minimun number maitaining the oscillation amplitude according the backfeed loop, diminishs the influence caused by the outside? factors, such as voltage change, which turely realizes the low power consumption Colpittis crystal oscillating circuit.
The following are the figures of the crystal oscillator:
P1 circuit structured flowchart；
P2 oscillation and level detection function frame chart；
P3 circuit theory chart of each module ；
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