Electronic device and control method

Abstract

The invention relates to an electronic device and a control method. The electronic device comprises a voltage-controlled oscillator and a biasing circuit. The voltage-controlled oscillator comprises a variable capacitor, and outputs oscillation frequency at a first temperature. The biasing circuit is coupled with the variable capacitor, provides a first bias voltage to the variable capacitor at the first temperature, and provides a second bias voltage to the variable capacitor at a second temperature; the variable capacitor has a first temperature coefficient; and the biasing circuit generates the first bias voltage and the second bias voltage according to the value of the first temperature coefficient and the value of a second temperature coefficient. The bias circuit provides the different bias voltages to the variable capacitor in the voltage-controlled oscillator at the different temperatures, so that the capacitance value of the variable capacitor keeps unchanged, and thus the oscillation frequency output by the voltage-controlled oscillator target can be prevented from being affected by temperature, and occurrence of oscillation frequency shift is avoided.

Description

technical field [0001] This case relates to an electronic device and a control method, and in particular to an electronic device and a control method whose oscillation frequency is not affected by temperature. Background technique [0002] Current communication systems and microprocessors often use phase-locked loop circuits to provide a stable high-frequency frequency. Therefore, phase-locked loop circuits are widely used in electronic products such as digital TVs and communication chips. [0003] Generally speaking, the PLL circuit includes coarse-tune and fine-tune circuit blocks. Firstly, the coarse adjustment circuit block controls a digital controlled capacitor array (Digital Controlled Capacitor Array, DCCA) according to the digital signal, thereby changing the capacitance of the LC resonant cavity, and then preliminarily selects an appropriate frequency band. After the frequency band is selected, the capacitance of the LC resonant cavity is changed by fine-tuning th...

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Problems solved by technology

[0004] However, the varactor capacitance in the fine adjustment circuit block will change with temperature, which will also affect the oscillation frequency output by the phase-locked loop circuit

Therefore, when the fluctuation of the oscillation frequency exceeds the adjustable range of the fine-tuning circuit block, the phase-locked loop cannot stabilize and cause a lock-out (lose lock)

[0005] The current common way to deal with this phenomenon is to set an additional varactor in the phase-locked loop circuit, so that the capacitance change of the additional varactor with temperature and the capacitance change of the varactor in the original fine-tuning circuit block with temperature cancel each other out , so as to reduce the offset of the oscillation frequency with respect to temperature. However, the additional varactor increases the capacitance in the system at the same time, so it inevitably reduces the adjustable range of the fine adjustment circuit block, and the additional setting The varactor also introduces a new noise interference path

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