Pocket Cube

A voltage-controlled oscillator or VCO is an electronic oscillator whose oscillation frequency is controlled by a voltage input. The applied input voltage determines the instantaneous oscillation frequency. Consequently, modulating signals applied to control input may cause frequency modulation (FM) or phase modulation (PM). A VCO may also be part of a phase-locked loop.

A microwave (12-18 GHz) Voltage Controlled Oscillator

Types of VCO

Template:Unsourced section VCOs can be generally categorized into two groups based on the type of waveform produced: 1) harmonic oscillators, and 2) relaxation oscillators.

Linear or harmonic oscillators generate a sinusoidal waveform. Harmonic oscillators in electronics usually consist of a resonator with an amplifier that replaces the resonator losses (to prevent the amplitude from decaying) and isolates the resonator from the output (so the load does not affect the resonator). Some examples of harmonic oscillators are LC-tank oscillators and crystal oscillators. In a voltage-controlled oscillator, a voltage input controls the resonant frequency. A varactor diode's capacitance is controlled by the voltage across the diode. Consequently, a varactor can be used to change the capacitance (and hence the frequency) of an LC tank. A varactor can also change ("pull") the resonant frequency of a crystal resonator.

Relaxation oscillators can generate a sawtooth or triangular waveform. They are commonly used in monolithic integrated circuits (ICs). They can provide a wide range of operational frequencies with a minimal number of external components. Relaxation oscillator VCOs can have three topologies: 1) grounded-capacitor VCOs, 2) emitter-coupled VCOs, and 3) delay-based ring VCOs.To succeed in selling a home, it is advisable be competent in real estate advertising and marketing, authorized, monetary, operational aspects, and other information and skills. This is essential as a result of you want to negotiate with more and more sophisticated buyers. You could outperform rivals, use latest technologies, and stay ahead of the fast altering market.

Home is where the center is, and choosing the right house is a part of guaranteeing a contented expertise in Singapore. Most expats sign up for a two-year lease with the option to resume, so it is value taking the time to choose a neighbourhood that has the services you want. The experts at Expat Realtor have compiled the next data that will help you negotiate your means by way of the property minefield. Some government state properties for rent. Over 2000 units available for lease however occupancy is often excessive. Some properties come under a bidding system. Their property brokers embody DTZ and United Premas. Up to date serviced residences located just off Orchard Highway. one hundred sixty Orchard Highway, #06-01 Orchard Level, Singapore 238842. Institute Of Property Agents

There is no such thing as a deal too small. Property agents who're willing to find time for any deal even when the commission is small are those you want in your side. They also show humbleness and might relate with the average Singaporean higher. Relentlessly pursuing any deal, calling prospects even without being prompted. Even when they get rejected a hundred times, they still come back for more. These are the property brokers who will find consumers what they want finally, and who would be the most profitable in what they do. four. Honesty and Integrity

As a realtor, you're our own business. Due to this fact, it is imperative that you handle yours prices and spend money correctly in order to market your property successfully. Also, beware of mentors who always ask you to pay for pointless costs. Such mentors typically are recruiting to develop a staff and see you as a option to defray advertising and marketing prices. For foreigners who want to register with CEA as salespersons, they might want to have a valid Employment Cross (EP) issued by the Ministry of Manpower (MOM). They should consult an property agent that is ready to assist their future registration software, who would then examine with CEA. Thereafter, after they register for the RES Course, they might want to produce a letter of assist from the property agent."

Main Real Property Brokers with in depth local knowledge, Carole Ann, Elizabeth and their group of extremely skilled property consultants provide a personalised service, for those looking to buy, lease or promote in Singapore. Relocation companies out there. Properties for the aesthete. Boutique real property agency for architecturally distinguished, unique properties for rent and on the market. Caters to the niche market of design-savvy people. Sale, letting and property management and taxation services. three Shenton Means, #10-08 Shenton Home, Singapore 068805. Buy property, promote or leasing estate company. 430 Lorong 6 Toa Payoh, #08-01 OrangeTee Constructing, Singapore 319402. HIGH Date / Age of property Estate Agents and Home Search Services Property Information Highlights Prime Achievers

From the above info, you may see that saving on agent's commission will not cover the expenses wanted to market your home efficiently. As well as, it's essential make investments a whole lot of time, vitality and effort. By taking yourself away from your work and other endeavors, additionally, you will incur unnecessary opportunity prices. There may be additionally no assurance you could beat the market and get the outcomes you need. That is why you want an agent - not simply an ordinary agent - you want knowledgeable and competent specialist, geared up with the best instruments and knowledge to serve you and lead you to success! Within the midst of this ‘uniquely Singapore' Property GSS, our most needed foreign customers are nowhere to be seen. Different types of Public Residential properties

Based on Kelvin, other agents may also make use of your agent's listings. "If your pricing is on the excessive aspect, these brokers may use your house to persuade their patrons why Http://Trafficstooges.Com/Singapore-Property-Condominium they should purchase another residence." To counter this, Kelvin says it is crucial for your agent to supply a current market analysis before putting up your private home for sale. "This helps you worth your property appropriately and realistically." When property is made accessible (HIGH is issued) to the client. Becoming a successful property agent is a distinct story altogether! Hi, I would like to ask how I might be a property agent and whether there are courses I might take. And if I need to be at a certain age. www. Property BUYER com.sg (your impartial Mortgage Advisor) In private properties in The first two of these types operate similarly. The time spent in each state depends on the rate of charge or discharge of a capacitor. The delay-based ring VCO operates somewhat differently however. For this type, the gain stages are connected in a ring. The output frequency is then a function of the delay in each stage.

Harmonic oscillator VCOs have these advantages over relaxation oscillators.

• Frequency stability with respect to temperature, noise, and power supply is much better for harmonic oscillator VCOs.
• They have good accuracy for frequency control since the frequency is controlled by a crystal or tank circuit.To succeed in selling a home, it is advisable be competent in real estate advertising and marketing, authorized, monetary, operational aspects, and other information and skills. This is essential as a result of you want to negotiate with more and more sophisticated buyers. You could outperform rivals, use latest technologies, and stay ahead of the fast altering market.
  
  Home is where the center is, and choosing the right house is a part of guaranteeing a contented expertise in Singapore. Most expats sign up for a two-year lease with the option to resume, so it is value taking the time to choose a neighbourhood that has the services you want. The experts at Expat Realtor have compiled the next data that will help you negotiate your means by way of the property minefield. Some government state properties for rent. Over 2000 units available for lease however occupancy is often excessive. Some properties come under a bidding system. Their property brokers embody DTZ and United Premas. Up to date serviced residences located just off Orchard Highway. one hundred sixty Orchard Highway, #06-01 Orchard Level, Singapore 238842. Institute Of Property Agents
  
  There is no such thing as a deal too small. Property agents who're willing to find time for any deal even when the commission is small are those you want in your side. They also show humbleness and might relate with the average Singaporean higher. Relentlessly pursuing any deal, calling prospects even without being prompted. Even when they get rejected a hundred times, they still come back for more. These are the property brokers who will find consumers what they want finally, and who would be the most profitable in what they do. four. Honesty and Integrity
  
  As a realtor, you're our own business. Due to this fact, it is imperative that you handle yours prices and spend money correctly in order to market your property successfully. Also, beware of mentors who always ask you to pay for pointless costs. Such mentors typically are recruiting to develop a staff and see you as a option to defray advertising and marketing prices. For foreigners who want to register with CEA as salespersons, they might want to have a valid Employment Cross (EP) issued by the Ministry of Manpower (MOM). They should consult an property agent that is ready to assist their future registration software, who would then examine with CEA. Thereafter, after they register for the RES Course, they might want to produce a letter of assist from the property agent."
  
  Main Real Property Brokers with in depth local knowledge, Carole Ann, Elizabeth and their group of extremely skilled property consultants provide a personalised service, for those looking to buy, lease or promote in Singapore. Relocation companies out there. Properties for the aesthete. Boutique real property agency for architecturally distinguished, unique properties for rent and on the market. Caters to the niche market of design-savvy people. Sale, letting and property management and taxation services. three Shenton Means, #10-08 Shenton Home, Singapore 068805. Buy property, promote or leasing estate company. 430 Lorong 6 Toa Payoh, #08-01 OrangeTee Constructing, Singapore 319402. HIGH Date / Age of property Estate Agents and Home Search Services Property Information Highlights Prime Achievers
  
  From the above info, you may see that saving on agent's commission will not cover the expenses wanted to market your home efficiently. As well as, it's essential make investments a whole lot of time, vitality and effort. By taking yourself away from your work and other endeavors, additionally, you will incur unnecessary opportunity prices. There may be additionally no assurance you could beat the market and get the outcomes you need. That is why you want an agent - not simply an ordinary agent - you want knowledgeable and competent specialist, geared up with the best instruments and knowledge to serve you and lead you to success! Within the midst of this ‘uniquely Singapore' Property GSS, our most needed foreign customers are nowhere to be seen. Different types of Public Residential properties
  
  Based on Kelvin, other agents may also make use of your agent's listings. "If your pricing is on the excessive aspect, these brokers may use your house to persuade their patrons why Http://Trafficstooges.Com/Singapore-Property-Condominium they should purchase another residence." To counter this, Kelvin says it is crucial for your agent to supply a current market analysis before putting up your private home for sale. "This helps you worth your property appropriately and realistically." When property is made accessible (HIGH is issued) to the client. Becoming a successful property agent is a distinct story altogether! Hi, I would like to ask how I might be a property agent and whether there are courses I might take. And if I need to be at a certain age. www. Property BUYER com.sg (your impartial Mortgage Advisor) In private properties in

A disadvantage of harmonic oscillator VCOs is that they cannot be easily implemented in monolithic ICs.To succeed in selling a home, it is advisable be competent in real estate advertising and marketing, authorized, monetary, operational aspects, and other information and skills. This is essential as a result of you want to negotiate with more and more sophisticated buyers. You could outperform rivals, use latest technologies, and stay ahead of the fast altering market.

Home is where the center is, and choosing the right house is a part of guaranteeing a contented expertise in Singapore. Most expats sign up for a two-year lease with the option to resume, so it is value taking the time to choose a neighbourhood that has the services you want. The experts at Expat Realtor have compiled the next data that will help you negotiate your means by way of the property minefield. Some government state properties for rent. Over 2000 units available for lease however occupancy is often excessive. Some properties come under a bidding system. Their property brokers embody DTZ and United Premas. Up to date serviced residences located just off Orchard Highway. one hundred sixty Orchard Highway, #06-01 Orchard Level, Singapore 238842. Institute Of Property Agents

There is no such thing as a deal too small. Property agents who're willing to find time for any deal even when the commission is small are those you want in your side. They also show humbleness and might relate with the average Singaporean higher. Relentlessly pursuing any deal, calling prospects even without being prompted. Even when they get rejected a hundred times, they still come back for more. These are the property brokers who will find consumers what they want finally, and who would be the most profitable in what they do. four. Honesty and Integrity

As a realtor, you're our own business. Due to this fact, it is imperative that you handle yours prices and spend money correctly in order to market your property successfully. Also, beware of mentors who always ask you to pay for pointless costs. Such mentors typically are recruiting to develop a staff and see you as a option to defray advertising and marketing prices. For foreigners who want to register with CEA as salespersons, they might want to have a valid Employment Cross (EP) issued by the Ministry of Manpower (MOM). They should consult an property agent that is ready to assist their future registration software, who would then examine with CEA. Thereafter, after they register for the RES Course, they might want to produce a letter of assist from the property agent."

Main Real Property Brokers with in depth local knowledge, Carole Ann, Elizabeth and their group of extremely skilled property consultants provide a personalised service, for those looking to buy, lease or promote in Singapore. Relocation companies out there. Properties for the aesthete. Boutique real property agency for architecturally distinguished, unique properties for rent and on the market. Caters to the niche market of design-savvy people. Sale, letting and property management and taxation services. three Shenton Means, #10-08 Shenton Home, Singapore 068805. Buy property, promote or leasing estate company. 430 Lorong 6 Toa Payoh, #08-01 OrangeTee Constructing, Singapore 319402. HIGH Date / Age of property Estate Agents and Home Search Services Property Information Highlights Prime Achievers

From the above info, you may see that saving on agent's commission will not cover the expenses wanted to market your home efficiently. As well as, it's essential make investments a whole lot of time, vitality and effort. By taking yourself away from your work and other endeavors, additionally, you will incur unnecessary opportunity prices. There may be additionally no assurance you could beat the market and get the outcomes you need. That is why you want an agent - not simply an ordinary agent - you want knowledgeable and competent specialist, geared up with the best instruments and knowledge to serve you and lead you to success! Within the midst of this ‘uniquely Singapore' Property GSS, our most needed foreign customers are nowhere to be seen. Different types of Public Residential properties

Based on Kelvin, other agents may also make use of your agent's listings. "If your pricing is on the excessive aspect, these brokers may use your house to persuade their patrons why Http://Trafficstooges.Com/Singapore-Property-Condominium they should purchase another residence." To counter this, Kelvin says it is crucial for your agent to supply a current market analysis before putting up your private home for sale. "This helps you worth your property appropriately and realistically." When property is made accessible (HIGH is issued) to the client. Becoming a successful property agent is a distinct story altogether! Hi, I would like to ask how I might be a property agent and whether there are courses I might take. And if I need to be at a certain age. www. Property BUYER com.sg (your impartial Mortgage Advisor) In private properties in Relaxation oscillator VCOs are better suited for this technology.Template:Cn Relaxation VCOs are also tunable over a wider range of frequencies.

Control of frequency in VCOs

Voltage-controlled oscillator schematic - audio

A voltage-controlled capacitor is one method of making an LC oscillator vary its frequency in response to a control voltage. Any reverse-biased semiconductor diode displays a measure of voltage-dependent capacitance and can be used to change the frequency of an oscillator by varying a control voltage applied to the diode. Special-purpose variable capacitance varactor diodes are available with well-characterized wide-ranging values of capacitance. Such devices are very convenient in the manufacture of voltage-controlled oscillators For low-frequency VCOs, other methods of varying the frequency (such as altering the charging rate of a capacitor by means of a voltage controlled current source) are used. See Function generator.

The frequency of a ring oscillator is controlled by varying either the supply voltage, the current available to each inverter stage, or the capacitive loading on each stage.

Voltage-controlled crystal oscillators

A voltage-controlled crystal oscillator (VCXO) is used for fine adjustment of the operating frequency. The frequency of a voltage-controlled crystal oscillator can be varied a few tens of parts per million (ppm), because the high Q factor of the crystals allows "pulling" over only a small range of frequencies.

There are two reasons for using a VCXO:

• To adjust the output frequency to match (or perhaps be some exact multiple of) an accurate external reference.
• Where the oscillator drives equipment that may generate radio-frequency interference, adding a varying voltage to its control input can disperse the interference spectrum to make it less objectionable. See spread spectrum clock.

A 26 MHz TCVCXO.

A temperature-compensated VCXO (TCVCXO) incorporates components that partially correct the dependence on temperature of the resonant frequency of the crystal. A smaller range of voltage control then suffices to stabilize the oscillator frequency in applications where temperature varies, such as heat buildup inside a transmitter.

Placing the oscillator in a temperature-controlled "oven" at a constant but higher-than-ambient temperature is another way to stabilize oscillator frequency. High stability crystal oscillator references often place the crystal in an oven and use a voltage input for fine control. The temperature is selected to be the turnover temperature: the temperature where small changes do not affect the resonance. The control voltage can be used to occasionally adjust the reference frequency to a NIST source. Sophisticated designs may also adjust the control voltage over time to compensate for crystal aging.Potter or Ceramic Artist Truman Bedell from Rexton, has interests which include ceramics, best property developers in singapore developers in singapore and scrabble. Was especially enthused after visiting Alejandro de Humboldt National Park.

VCO time-domain equations

$\ f_{tuning}(t)=K_{o}\cdot \ v_{in}(t)$

$\int f_{tuning}(t)\,dt=\theta _{out}(t)$

• $\ K_{o}$ is called the oscillator gain. Its units are hertz per volt.
• $\ f_{tuning}(t)$ is the symbol for the time-domain waveform that is the VCO's tunable frequency component.
• $\ \theta _{out}(t)$ is the symbol for the time-domain waveform that is the VCO's output phase.
• $\ v_{in}(t)$ is the time-domain symbol of the control (input) voltage of the VCO; it is sometimes also represented as $\ v_{tune}(t)$

VCO freq-domain equations

$\ F_{tuning}(s)=K_{o}\cdot \ V_{in}(s)$

$\ {F_{tuning}(s) \over s}=\Theta _{out}(s)$

Analog applications such as frequency modulation and frequency-shift keying often need to control an oscillator frequency with an input — a voltage-controlled oscillator (VCO). The functional relationship between the control voltage and the output frequency may not be linear. Over small ranges, the relationship is approximately linear, and linear control theory can be used.

There are devices called voltage-to-frequency converters (VFC). These devices are often designed to be very linear over a wide range of input voltages.

VCO design and circuits

Tuning range, tuning gain and phase noise are the important characteristics of a VCO. Generally low phase noise is preferred in the VCO. The noise present in the control signal and the tuning gain affect the phase noise; high noise or high tuning gain imply more phase noise. Other important elements that determine the phase noise are the transistor's flicker noise (1/f noise), the output power level, and the loaded Q of the resonator. See Leeson's equation. The low frequency flicker noise affects the phase noise because the flicker noise is heterodyned to the oscillator output frequency due to the active devices non-linear transfer function. The effect of flicker noise can be reduced with negative feedback that linearizes the transfer function (for example, emitter degeneration).

Leeson's expression for single-sideband (SSB) phase noise in dBc/Hz (decibels relative to output level per Hertz) is

$L(f_{m})=10\log {\bigg [}{\frac {1}{2}}{\bigg (}{\bigg (}{\frac {f_{0}}{2Q_{l}f_{m}}}{\bigg )}^{2}+1{\bigg )}{\bigg (}{\frac {f_{c}}{f_{m}}}+1{\bigg )}{\bigg (}{\frac {FkT}{P_{s}}}{\bigg )}{\bigg ]}$

where f₀ is the output frequency, Q_l is the loaded Q, f_m is the offset from the output frequency (Hz), f_c is the 1/f corner frequency, F is the noise factor of the amplifier, k is Boltzmann's constant, T is absolute temperature in Kelvins, and P_s is the oscillator output power.

Commonly used VCO circuits are the Clapp and Colpitts oscillators. The more widely used oscillator of the two is Colpitts and these oscillators are very similar in configuration.

VCOs generally have the lowest Q-factor of the used oscillators, and so suffer more jitter than the other types. The jitter can be made low enough for many applications (such as driving an ASIC), in which case VCOs enjoy the advantages of having no off-chip components (expensive) or on-chip inductors (low yields on generic CMOS processes). These oscillators also have larger tuning ranges than the other kinds, which improves yield and is sometimes a feature of the end product (for instance, the dot clock on a graphics card which drives a wide range of monitors).

Applications

VCOs are used in:

• Function generators,
• The production of electronic music, to generate variable tones,
• Phase-locked loops,
• Frequency synthesizers used in communication equipment.

Voltage-to-Frequency converters are voltage-controlled oscillators, with a highly linear relation between applied voltage and frequency. They are used to convert a slow analog signal (such as from a temperature transducer) to a digital signal for transmission over a long distance, since the frequency will not drift or be affected by noise. VCOs may have sine and/or square wave outputs. Function generators are low-frequency oscillators which feature multiple waveforms, typically sine, square, and triangle waves. Monolithic function generators are voltage-controlled. Analog phase-locked loops typically contain VCOs. High-frequency VCOs are usually used in phase-locked loops for radio receivers. Phase noise is the most important specification for them. Low-frequency VCOs are used in analog music synthesizers. For these, sweep range, linearity, and distortion are often most important specs. Audio-frequency VCOs for use in musical contexts have largely been superseded by their digital counterparts, DCOs, due to their output stability in the face of temperature changes during operation.

Voltage-controlled crystal oscillator as a clock generator

A clock generator is an oscillator that provides a timing signal to synchronize operations in digital circuits. VCXO clock generators are used in many areas such as digital TV, modems, transmitters and computers. Design parameters for a VCXO clock generator are tuning voltage range, center frequency, frequency tuning range and the timing jitter of the output signal. Jitter is a form of phase noise that must be minimised in applications such as radio receivers, transmitters and measuring equipment.

The tuning range of a VCXO is typically a few parts per million over a control voltage range of typically 0 to 3 volts. When a wider selection of clock frequencies is needed the VCXO output can be passed through digital divider circuits to obtain lower frequency(ies) or be fed to a PLL (Phase Locked Loop). ICs containing both a VCXO (for external crystal) and a PLL are available. A typical application is to provide clock frequencies in a range from 12 kHz to 96 kHz to an audio digital to analog converter.

See also

• VFO
• VCF
• VCA
• LFO
• modular synthesizer
• Numerically controlled oscillator (Also "digitally controlled oscillator" or DCO)
• Phase-locked loop

Notes

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References

43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.

External links

• schematics
• Designing VCOs and Buffers Using the UPA family of Dual Transistors