Digital VCO is not only essential element of a digital communications system, but also a variety of digital synthesizer and digital signal generator core. With the development of digital communications technology, data transmit rate and the accuracy rate is getting higher and higher requirements. How to achieve high-speed digital communication systems and high-frequency carrier signal must be addressed. The development of programmable logic devices and large-capacity storage solves this issue sheds some light on.
This issue used the AT89C51 single-chip to control DAC output voltage, then the output voltage controlled VCO output signal frequency. AT89C51 single-chip microcomputer issue mainly included peripheral circuit, key input, DAC0832 controlling and algorithm design.
The output frequency of the digital VCO was from 1kHz to 250kHz, and frequency resolution was 1KHz, output adjustable voltage was from 0V to 5V after debugging system, which achieved basic performance of VCO. The shortcomings were narrow output frequency scale and low resolution.
