Narrow-Band Colpitts Voltage Manipulated Oscillator Design and style Literature Essay

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Bilkent University

Electrical& Electronics Executive


Oscillators are one of the main building blocks in the electronic devices. They work on the principle of oscillation the industry periodic varying between the optimum and minimal value in the quantity. Oscillators mainly incorporate two parts: the active circuit plus the resonator. In active signal there are active circuit components like transistors or op-amps. Capacitors (C), Inductor (L) and resistors (R) makes the resonator as well as the frequency of the oscillator depends upon the resonator. An oscillator can be designed in many ways as well as the main types of the oscillators are: REMOTE CONTROL Oscillator, LC Oscillator, Colpitts, Hartley, Clapp, and Pierce. The main difference of the Volt quality controlled oscillator (VCO) from the other oscillator types is the oscillation regularity can be determined by Vcont volt quality. The adjustable capacitor (varactor) plays the key role right here, if the Vcont changes compared to the capacitance of the varactor alterations and this sooner or later changes the oscillation consistency. There are some essential points that require attention when designing an oscillator: Stability, Phase Noises, Gain, Q factor, Rate of recurrence Pushing and Pulling. With this report the brief data required to design a Colpitts VCO has and critical resources books, internet sources, application and lecture notes is analyzed.


In order to design a Colpitts VCO some meanings and some understanding is required to study. These matters and fundamental explanations are given; The characteristic and studies of Colpitts VCO;

Figure 1: Colpitts Oscillator


When there is an unknown two port network, to be able to determine what is in this black box we want s-parameters [4]. The figure and the explanation of the waves are given below;

Number 2: Two port network

Then the spreading matrix is established below;

Rate of recurrence Pushing:

Frequency pushing may be the VCO's awareness to supply concentration. Every oscillator needs a power which comes from the POWER voltage origin and the functioning frequency of the oscillators is usually sensitive for this DC power supply. That is to say, because DC volts changes the output frequency adjustments. Pushing is definitely expressed in Hz/V and is negative or positive. Frequency pushing effect can be reduced by using a high-Q resonator or by well-regulated power supply. [5]

Frequency Yanking:

Frequency pulling is the consistency variation due to changes in the impedance of the end result load. Put simply, we only measure the output frequency which includes impedance on the output of the oscillator and if ZL (output impedance) improvements the output regularity also improvements. It is usually particular at a load return lack of 12dB and everything possible phases, and is portrayed in Megahertz peak-to-peak. Frequency pulling may be minimized by isolating the load from the oscillator. [5]

Tuning Sensitivity:

This can be a slope from the tuning feature and is stated as frequency change per unit voltage change (MHz/V, etc . ).

Q factor (Q in the resonator):

Essentially Q factor is the rate of functioning frequency towards the bandwidth. Q=f0∆f0=ω0∆ω0

The loss is inversely proportional to the Queen. That is to say, in case you have a higher Queen, the energy loss is less.

Transmitting Line Theory:

To be able to develop an oscillator at RF, transmission theory should also be learned. Inside the microwave regularity region, electric power is considered to be in electric and magnetic areas that are led from one destination to another simply by some physical structure. The physical structures that are slowly move the power are called Transmission Range. Two cable line, englobant cable, tape line, microstrip line and slot line are some of the transmission collection types.

If the attribute impedance resistive is not really equal to the load impedance, part of the power is definitely reflected as well as the...

References: [1] Thomas H. Lee. The design of CMOS radio-frequency bundled circuits Cambridge University Press

[2] Guillermo Gonzalez. Foundations of Oscillator Circuit Design Artech Residence, Inc. 2007

[3] Matthew M. Radmanesh. Radio Consistency and Micro wave Electronics Illustrated, Princeton Lounge PTR

[4] Test& Measurement Application Note 95-1, S-Parameter Techniques for Quicker, More Accurate Network Design

[5] Minicircuits App Notes

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