1、压控高频 LC 振荡器的设计 1 Voltage control design of high frequency LC oscillators Student : Pxxx, physics and information engineering colleges Instructor : xxx, Jianghan University In recent years,with the rapid development of wireless communication technology, make the market for rf integrated circuit has h
2、ad a huge demand. In the rf circuit, the voltage control oscillation (VCO) occupied a very important position.With a wide range of applications.In the early stages of the radio technology development,it is used to produce high-frequency in transmitter carrier voltage,As a specialized superheterodyne
3、 receivers in the machine oscillator, be sending and receiving equipment basic components.Now the use of oscillator is more and more widely.For example: in radio communication, radio, and television equipment used to produce the need of the carrier and the machine oscillation signal；In the electroni
4、c measuring instruments used to produce all sorts of frequency sine signals, etc. Definition Oscillator is simply stated a frequency source, usually in a phase lock loop.Detailed said is that a device dont need the signal to their own motivation, Dc power can be transformed into Ac power .Generally
5、fall into the positive feedback and negative resistance.The so-called oscillating,Its meaning is to allude to exchange,.Oscillator includes a never oscillation to process and function of oscillation.Can completion from dc to ac power transformation,This device can be called oscillator. Oscillator wo
6、rking principle LC circuit consisting of capacitors and inductors, electric field and the conversion of magnetic energy production process free oscillation. To maintain the oscillation also has a positive feedback amplifier circuit, the LC oscillator is divided into a transformer coupled and three-p
7、oint oscillator, many applications of quartz crystal quartz crystal oscillator, LC oscillator with an integrated operational amplifier. Exactly the same device can not be parameters in the state of the power the moment the two transistor occurs a change, this change due to increasingly strong role i
8、n the positive feedback, leading to reach a temporary steady state. During the temporary steady state to another transistor by capacitance gradually 压控高频 LC 振荡器的设计 2 charge conduction or closed state of the flip to another temporary steady state. This cycle of formation of oscillation. The classific
9、ation of oscillator Oscillator are divided into RC, LC oscillators and crystal oscillator,1. The RC oscillator Use the RC network as frequency selective phase shifting network is called RC sinusoidal oscillator Belong to audio oscillator. 2. LC oscillators Use the LC oscillation loop as move and fre
10、quency selective network of Positive feedback oscillator is called LC oscillators. LC oscillators classification: (1) transformer coupling Single pipe LC sinusoidal oscillator difference to the LC sinusoidal oscillator (2) Three point pattern Condenser three point pattern oscillator, three point typ
11、e oscillator (3)The improvement of three type Clapp oscillator, Seiler oscillator (4)The difference of tube oscillator 3.Crystal oscillator The oscillation frequency of the oscillator by quartz crystal controlled oscillator. The temperature coefficient oscillator Temperature coefficient oscillator r
12、efers to an oscillator, its oscillation frequency and temperature have a specific relationship between the different temperatures corresponding to different oscillation frequencies. Conversely, measuring the output frequency of the oscillator, we can measure the temperature. High temperature coeffic
13、ient oscillator: its oscillation frequency is affected by temperature, a slight change in temperature, the frequency will change a lot, that is temperature sensitive, and more for the temperature sensor. low temperature coefficient oscillator: the oscillation frequency temperature has little effect,
14、 even if the temperature varies greatly, its frequency is essentially the same. Quartz crystal oscillator Quartz crystal oscillator and non-temperature compensated crystal oscillators, temperature compensated crystal oscillator (TCXO), voltage controlled crystal oscillator (VCXO), thermostatically c
15、ontrolled crystal oscillator (OCXO) and digital / p compensated crystal oscillator (DCXO / MCXO) and other types. Among them, temperature compensated crystal oscillator is the simplest one, in the Japanese Industrial Standard (JIS), called the standard package crystal oscillator (SPXO). Now SPXO exa
16、mple, a brief overview of the structure and working principle of the quartz crystal oscillator. 压控高频 LC 振荡器的设计 3 Quartz crystals, natural and artificial, is an important piezoelectric crystal materials. The quartz crystal itself is not an oscillator, it is only by means of the active encouragement a
17、nd passive reactance network before oscillation. SPXO is mainly composed of high crystal resonators (crystal oscillator) and feedback oscillation circuit of quality factor (Q). The quartz crystal oscillator is an important component in the oscillator, the frequency of the crystal (fundamental freque
18、ncy or the n-th harmonic frequency) and its temperature characteristics depend largely on the cutting orientation. Pole on the crystal oscillator board to impose an alternating voltage, it will cause the chip to produce mechanical deformation vibration, this phenomenon is the so-called inverse piezo
19、electric effect. When the applied voltage frequency is equal to the natural frequency of the crystal resonator, piezoelectric resonator, resulting in mechanical deformation amplitude increases suddenly. With the metal plate between the electrostatic capacitance； L, and C is the piezoelectric resonat
20、or equivalent parameters； R is the equivalent resistance of the vibration friction loss. Quartz crystal resonators, there is a series resonant frequency fos (1/2), there is also a parallel resonant frequency fop (1/2). Due to a very small difference between the Co. C, fop and fos, and the R OL, the
21、R 1/OC resonant circuit quality factor Q is very high (up to several millions), so that of the quartz crystal resonator the oscillator frequency stability is very high, up to 10-12 / day. Quartz crystal oscillation frequency can approximate in fos Department, can also work around the in fop, a quart
22、z crystal oscillator can be divided into two kinds of the series and shunt. Quartz crystal resonator and its equivalent circuit, replace the components of the LC oscillator constitutes a resonant circuit inductance (L) and capacitance (C), it is easy to understand the working principle of the crysta
23、l oscillator. SPXO the total accuracy (including initial accuracy and temperature, voltage, and load changes) can be up to 25ppm. SPXO neither temperature compensated temperature control measures, and its frequency-temperature characteristics almost entirely determined by the frequency-temperature c
24、haracteristics of quartz crystal oscillator. Within the range of 0 70 SPXO frequency stability is typically 20 1000ppm, SPXO can be used as a clock frequency oscillator. Temperature compensated crystal oscillator (TCXO) TCXO is generated by the ambient temperature change of a quartz crystal oscillator oscillation frequency change reduction through additional temperature compensation circuitry.
