Oscillating device for adjustable oscillating frequency

Abstract

The invention discloses an oscillating device, comprising a bias-voltage circuit, an oscillator, a testing circuit and a selecting circuit. The bias-voltage circuit is used to produce at least one bias-voltage signal, and the bias-voltage circuit comprises a connection port that can be coupled to a resistance element to control the frequency of oscillating signals or coupled to a clock source to receive external reference clock. The bias-voltage signals coupled to the bias-voltage circuit produce oscillating signals. The testing circuit is coupled to the connection port to test whether the connecting port is connected to the resistance element or the clock source so as to generate selecting signals automatically. The selecting circuit comprises an AND gate coupled to the oscillator and the selecting signals and an OR gate coupled to AND gate and the connection port to judge whether the CLOCK is external or internal oscillating signal.

Description

technical field [0001] The invention relates to an oscillating device, in particular to an oscillating device which can adjust the oscillating frequency and has a high power supply rejection ratio (High Power Supply Rejection Ratio). Background technique [0002] In various digital systems, a clock generator is needed to provide a clock signal as the basis for control. Generally, a low-frequency clock provided by the outside is used to generate a high-frequency clock signal through a frequency multiplication circuit in the chip; the other is to generate a clock through a self-oscillating circuit. The former requires an external low-frequency oscillator component, and its implementation circuit is mainly based on a phase-locked loop, while the latter uses a simple circuit design to provide a clock signal. This structure is very suitable for small-sized thin-film transistor liquid crystal displays (Thin In the Film Transistor-Liquid Crystal Display (TFT-LCD) drive circuit, th...

AI Technical Summary

Problems solved by technology

It can be seen that when the external environment changes, V SW , the values ​​of C and I will also change and cause the frequency shift of the oscillation signal

On the other hand, in the voltage-to-current converter (Voltage-to-current converter) in the traditional voltage-controlled oscillator, the resistor responsible for determining the bias current is a fixed value, making it impossible to adjust the resistor value when the frequency shift occurs in actual operation to correct the oscillation signal frequency

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