The design and implementation of the digital down converter. Frequency tx or rx range voltage tuning range linear tuning nonlinear tuning fig. This paper presents a lowpower digitally controlled oscillator dco. One more robust way this is typically done is to use a numerically controlled oscillator nco. A portable highfrequency digitally controlled oscillator dco.
A low power digitally controlled oscillator using 0. Introduction numerically controlled oscillator nco is an important component in many digital communication systems such as digital radio and modems, software defined radios, digital downup converters for cellular and pcs base stations, etc 1. Digitally controlled oscillator dco design help required. Tuning is usually more precise and consistent with a dco, compared to a vco. The dco first appeared in the 1980s as a sort of intermediate step between the allanalog vco, and the all digital.
This programmable device supports any frequency, 1. The proposed circuit has a simple structure, and the power consumption of this. Electro tech is an online community with over 170,000 members who enjoy talking about and building electronic circuits, projects and gadgets. Reducing development risk in communications applications with. Msp430 family architectural overview 23 2 the msp430 devices contain the following main functions. A sub10\mu\hboxw digitally controlled oscillator based. Abstract this report describes the d e v e 1 o p m e n t of a digital voltage controlled oscillator phase lock loop. This architecture achieves a frequency resolution less than 1khz. Abstracta new structure for digitalk controlled oscillator dco is presented in this paper. The dco achieves frequency quantization step of 300 hz without any dithering. A crystalbased digital ring oscillator request pdf. Ch3 digitallycontrolled oscillator with logic gatebased.
It achieves both the higher frequency resolution and a large frequency tuning range with a small differential nonlinearity. A digitally controlled oscillator is presented as a suitable solution for all digital frequency lock loops. A digitally controlled crystal oscillator dcxo generates a highquality base stationsynchronized frequency reference such that the transmitted carrier frequencies and the received symbol rates are accurate to within 0. For some applications thats a good thing, and for others its not. Pdf fpga implementation and power efficient cordic based. Optimization of digitally controlled oscillator with low power 1 a. The name is analogous with voltage controlled oscillator.
A harmonic oscillator design methodology based on describing functions jesper bank department of signals and systems. Voltage controlled oscillators tuning a voltage controlled oscillator vco is an oscillator whose frequency can be varied by a voltage or current. And use the ad9854 interface to control the phase of the output. Ch3 digitallycontrolled oscillator with logic gate based tunable active inductor 3.
The proposed dco circuit uses control codes of thermometer type to reduce jitters. The proposed calibration circuit can solve the nonmonotonic problem when the coarsetuning control code is changed. A low power cmos design of an all digital phase locked loop a thesis presented by jun zhao to the department of department of electrical and computer engineering in partial ful llment of the requirements. Dcos were designed to overcome the tuning stability limitations of early vco designs. While dcos offer improved pitch stability and tuning, the oscillators are still analog, so they do not offer the wide range of waveshape possibilities of true digital. Ring oscillator, digitally controlled oscillator, digital. Design of high frequency, low phase noise lc digitally. Optimization of digitally controlled oscillator with low power. Digitally controlled oscillator with clock switching on 8bit. One digital controlled oscillator dco with rctype characteristics one crystal oscillator used for lowfrequency crystals watch crystals, e. Mcgunigaj goddard space flight center introduction a key component in the design of tracking and telemetry receivers is the carrierloop voltage controlled oscillator vco. Microsemis nco clock generators can be programmed to generate any frequency as needed to. Design of low power 6bit digitallycontrolled oscillator. Chitra 1 department of ece, vickram college of engineering, enathi630561, india 2 department of ece, government polytechnic for women, madurai625001, india abstract.
Design of low power 6bit digitallycontrolled oscillator dco mohammad anisur rahman, habibah binti mohamed, mamun bin ibne reaz, sawal hamid md ali, and wan mimi diyana wan zaki department of electrical, electronic and systems engineering faculty of engineering and built environment. Digitally controlled oscillator dcobased architecture. The system consists of a bias circuit, currentvoltage converters and a current controlled oscillator, which is implemented using logdomain circuits. The dco includes an 8 phase currentcontrolled ring oscillator, a digitally controlled current source. Staszewski et al digitally controlled oscillator dco based architecture 817 a b fig. Pvt is calibrated to the middle of the bluetooth band with code 111. The idea is that a control voltage is generated by the a microcontroller arduino which is used via the 2 op amps, resistor and capacitor network which forms a integrator circuit. A digitally controlled oscillator or dco is used in synthesizers, microcontrollers, and software defined radios. Us9020454b2 linearization and calibration predistortion of. While dcos offer improved pitch stability and tuning, the oscillators are still analog, so they do not offer the wide range of waveshape possibilities of true digital oscillators. Applications edit vcos are used in function generators. The proposed dco implemented with a standard performance 65nm cmos process can output frequency ranges from 58.
The 26 digitally controlled crystal oscillator dcxo combines the frequency stability of a crystal oscillator source with the flexibility of direct digital synthesis dds in a temperature controlled housing to provide a highly accurate output signal. This brief presents an all digitally controlled oscillator dco design with two newly proposed hysteresis delay cells hdcs for wireless body area network applications. A novel structure for portable digitally controlled oscillator. Digitally controlled clock generators are less sensitive and easier to implement. Abstractwe describe a digitally controlled oscillator dco which compensates the frequency variations for process, voltage, and temperature pvt variations with an accuracy of 2. The output frequency of the voltage controlled oscillator is either sinusoidal or sawtooth. A it is certainly possible to use the ad9854 as a digitally programmable oscillator. The oscillator module provides an easy and smooth process for switching operating frequencies. W digitally controlled oscillator based on hysteresis delay cell topologies for wban applications. Similarly, its digital counterpart consist of a phase detector, loop filter and digitally. According to circuit topologies, the two hdcs are defined as onoff and cascaded hdcs that provide various propagation delay values. A digitally controlled oscillator, or dco, is an oscillator circuit that generates an analog signal, but whose frequency is controlled by a digital control input as opposed to a voltage controlled oscillator, whose frequency is set by a control voltage. A digital voltagecontrolled oscillator for phase lock loops. The lowpower cmos dco is designed based on the ring oscillator implemented with schmitt trigger inverters.
Design of low power 6bit digitallycontrolled oscillator dco mohammad anisur rahman, habibah binti mohamed, mamun bin ibne reaz, sawal hamid. In this paper, an ultra low power 15bit digitally controlled oscillator is proposed. A novel digitally controlled oscillator dco based architecture for frequency synthesis in wireless rf applications is proposed and demonstrated. A novel digitally controlled oscillator dcobased architecture for frequency synthesis in wireless rf applications is proposed and demonstrated. Introduction numerically controlled oscillator nco is an important component in many digital communication systems such as digital radio and modems, software defined radios, digital. Realization of fpga based numerically controlled oscillator. A digitally controlled oscillator dco for the frequency band of 17001900 mhz is presented. Powersaving features have no effect on the internal oscillator, which. A portable highfrequency digitally controlled oscillator. A lowpower and lowjitter 12bit cmos digitally controlled oscillator dco design is presented. A large frequencytracking range and high phase stability are conflicting requirements of a con ventional voltage controlled oscillator vco. How digitally controlled oscillators dcos work synthtopia. The digital controlled oscillator is designed using modified counters which reduce the delay compared to traditional methods. Fine frequency resolution is achieved through highspeed spl sigmaspl delta dithering.
Digitally controlled oscillator for alldigital frequency. By using a gated digital controlled oscillator gdco, the proposed gdco based phase detector may reduce the cost of this architecture and achieve a wide linear range. In fact is you use the ad9854 in psk mode, you can switch between two. A monotonic digitally controlled oscillator with self. A precise based digitally controlled oscillator dco for all digital pll abstract. High frequency voltage controlled ring oscillators in.
First, the digitally controlled oscillator dco can be precisely steered with a step size as small as controlled oscillator. All digital control 14 digitally controlled oscillator dco based architecture for rf frequency synthesis in a deepsubmicrometer cmos process. Using a dco does not make a synthesizer digital or hybrid. The msp430 is a popular microcontroller, and on board is a neat little clock source, a digitally controlled oscillator, or dco. A digitally controlled oscillator based on a frequency synthesizer may serve as a digital alternative to analog voltage controlled oscillator circuits. As ring oscillator is a part of analog circuit design, so is the basic type of oscillator used in radio frequency integrated circuit design. Abstract a novel digitallycontrolled oscillator dco is reported.
A 900 mhz, voltage controlled oscillator vco in a 0. The proposed adpll architecture uses both a digital control mechanism and a ring oscillator and, hence, can be implemented with standard cells. Microsemis nco solutions can be used as free running clock generators or to build phase locked loops. Dec 09, 2008 i am trying to design a digitally controlled analogue oscillator. Basically, you have an accumulator that keeps track of the instantaneous phase of the oscillator, updated as follows. Design of cmos based ring oscillator linkedin slideshare. However analog pll are sensitive to process parameters variations and must be redesigned with changing technology 2. Performance of the dco is verified through a novel all digital phaselocked loop adpll designed with a. Lcbased dco circuit based on incrementally sized and matched varactor banks has been reported 5. A jittertoleranceenhanced cdr using a gdcobased phase. A digital voltage controlled oscillator forphase lockloops by dominick e. A precise based digitally controlled oscillator dco. The digitally controlled oscillator of 8bit pic microcontrollers offers a wide range of selectable frequencies for the system and peripheral clock sources.
The coarsefine architecture with binaryweighted delay stages is applied for the delay range and resolution optimization. In this way, the oscillation frequency can be tuned using the bias currents. Having described preferred embodiments for optimal dithering of a digitally controlled oscillator with clock dithering for gain and bandwidth control which are intended to be illustrative and not limiting, it. The architecture of the msp430 family is based on a memorytomemory architecture. Most lc dcos around 10 ghz are designed using 65 nm and newer technology, resulting in a. A voltage controlled oscillator vco based analogtodigital converter adc is a time based architecture with a firstorder noiseshaping property, which can be implemented using a vco and. The increment decrement counter is modified from previous. Design of low noise 16bit cmos digitally controlled oscillator. Digitally controlled oscillator how is digitally controlled. Abstract a novel digitally controlled oscillator dco based architecture for frequency synthesis in wireless rf applications is proposed and demonstrated. All other components are fully digital and modular, allowing portability to any cmos process and customization for different applications.
Design of cmos based ring oscillator by ushaswini chowdary. The cmos dco is designed based on a ring oscillator. A voltage controlled oscillator is a widely used electronic oscillator where the input tuning voltage determines the oscillation frequency. It deliberately avoids any use of an analog tuning voltage control line.
Fpga implementation of modified adppl for dual clock. These hdcs form a simple oscillator structure based. A low power 6bit cmos ring based digitally controlled oscillator dco. Digitally controlled oscillator dcobased architecture for.
Usually tuning is handled digitally with these types of oscillators, but voltage controlled digital oscillators do exist. This oscillator can be used for everything from setting baud rates. A key component is the digitally controlled oscillator dco 56, which avoids any analog tuning controls. In this paper, cmos digitally controlled oscillator. Optimization of digitally controlled oscillator with low power doi. A novel digitallycontrolled oscillator dco is reported. Perrott 5 integern frequency synthesizers use digital counter structure to divide vco frequencyconstraint. A novel structure for portable digitally controlled oscillator jinjev jong, chenyi lee dept. It deliberately avoids any use of an analog tuning voltage control. A low power cmos design of an all digital phase locked loop. Digitally controlled crystal oscillators dcxo apis digitally controlled crystal oscillators dcxo combine the frequency stability of a crystal oscillator source with the flexibility of direct digital synthesis dds in a temperature controlled housing to provide a highly accurate output signal.
Simulations of the analyzed dco using 250nm cmos technology achieve controllable different frequency range with a wide linearity. In this paper, cmos digitally controlled oscillator dco design is analyzed for 416 bits. A lowpower digitally controlled oscillator for all digital. Utilizing a new capacitive load, the new dco is capable of producing much higher output frequencies than existing dcos. The proposed dco is designed based on a segmental coarsetuning stage and employs hysteresis delay cell hdc and digitally controlled varactor dcv in the finetuning stage.
Digitally controlled oscillator dco based architecture for rf frequency synthesis in a deepsubmicrometer cmos process. Frequency transversal example for the implemented dco. Us88840b2 optimal dithering of a digitally controlled. A digitally controlled oscillator dco based on capacitive degeneration in lctank is also implemented. Introduction millions of transistors can be integrated on a single chip so that system on chip soc can be designed.
Oscillator design guide structure the oscillator designguide is integrated into agilent eesofs advanced design system environment, working as a smart library and interactive handbook for the creation of useful. Oscillator designguide reference this manuals provides reference information on the use of the oscillator designguide. Top 4 download periodically updates software information of oscillator full versions from the publishers, but some information may be slightly outofdate using warez version, crack, warez passwords, patches, serial numbers, registration codes, key generator, pirate key, keymaker or keygen for oscillator license key is illegal. Voltage controlled oscillators are important components in many applications such. In local oscillator applications, the vco frequency must be able to be varied over the rx or tx range quickly. Numerically controlled oscillator the numerically controlled oscillator ncox module is a timer that uses the overflow of an accumulator to create an output signal. The accumulator overflow is controlled by an adjustable increment value rather than just a single clock pulse or postscaler increment. See the specific data sheet for the operating frequency range of the target device. Frequency synthesizers are used in many modern devices such as radio receivers, televisions, mobile telephones, radiotelephones, walkietalkies, cb radios, cable television converter boxes satellite receivers, and gps. Keywords numerically controlled oscillator, fpga, lookup table, register i. The vco must provide sufficient f requencypulling range to accom. Digitally controlled oscillator electronic music wiki.