Design Of Low-power Dissipation And Adjustable Frequency Oscillating Circuit

In recent years, with the speedy development of the personal mobilecommunication, the market of radio frequency and wireless has attracted moreattention. The frequency sources are the most important part of much electronicsystem, but it is the core of wireless communication terminal. The VCO is a kind ofoscillator whose oscillation frequency changes with the outside voltage. In manymodern communication systems, VCO is the adjustable signal source, and is used torealize the fast frequency adjust of PLL and other frequency synthesizer. VCO iswidely used in mobile phone, satellite communication terminal, base station, radar,missile guidance system, military communication system, digital wirelesscommunication, optical multiplex device, optical transmitter and other electronicsystem. The development of electronic equipment and electronic system push theupdate and advance of VCO technology constantly. Let us see the modern and futurewireless terminal. Especially the wireless mobile communication system. Not onlyneeds very high frequency, but also have a constantly need of militarization,lightweight, high performance, multi-fictionalization, low-power consumption andlow cost.The purpose of this paper is to design a new kind of low-power dissipation andadjustable frequency oscillating circuit. On the basis of total research, the main workinclude：Firstly, we come up with a tentative design ideas based on the development andbasic knowledge about oscillator. Then we give a detail introduce of every part,including the fundamental, design and circuit simulate. Change and improve the basiccircuit until we got what we wanted. Then put each part together rational, come upwith the whole design and improvement. At last, we introduce the method and noticeof layout design.Innovation point:1．Based on the intimacy and grasp of the basic circuit, we want to design a kindof oscillating circuit whose frequency are more stable and adjustable. After thetheoretical analysis, we unconnected the circuit and design a new oscillating circuitincluding voltage comparator, RS trigger and so on.2．Design of a new way to control the electric current, ensure the stability and adjustable of the oscillator frequency. In this circuit, we take a good use of theCascode current mirror and transmission gate connected the circuit according to thedigital combinatorial logic. Design a new kind of digital control circuit. It is morestable and adjustable than the old ways.3．Design of a kind of self-started circuit. In case they exist of unwanted zerobias point.when the power to electricity. If the entire transistor transmits zero currentwhen the power is on, then they will always be shut down. Add a kind of self-startedcircuit, ensure to get away from the zero point when the power to electricity.This chip uses0.7μm DPTM5V CMOS craft, and simulates the circuits with thesoftware called Cadence. Then adjust the parameter of each circuit according to theindicator, until the whole circuit reaches the target.