IMs are used in many industry sectors as the leading element to convert electrical energy into mechanical one. The main challenge is based on robustness and low cost. The performance of the motor speedcontrol required in the industrial drives depends on the application specifi- cations. In some applications, an open loopspeed varia- tion of the drive motor is enough. In others, feedback control is required for better speed regulation perform- ances. The performances of the speed regulation depend on the performances of the speed controller. In light of available literature, important aspects of the motor drive system, it is considered worthwhile to review it critically in order to find the gaps existing knowledge on the IM drive systems. Researchers have used various types of closed loop controllers for the IM rotor speed. PI con- trollers are widely and still used in the outer speedloop [1,2]. They have a simple structure and can offer a satis- factory performance for a wide range of operation. Due to the continuous variation in the plant parameters and the non linearities conditions, PI controllers may become unable to provide the required control performance [3,4]. These inherent disadvantages of the PI controllers have encouraged the replacement of this controller with adap- tive [5,6] and robust [7-9] control laws. Adaptive control laws impose a very computation burden while H∞ robust control requires the knowledge of the disturbances boundaries . Sliding mode control is also used in the
ABSTRACT: This work implements an energy efficient and high speedphaselockedloop (PLL) . The main block of PLL is Phase Frequency Detector (PFD), Charge Pump (CP), Low pass filter and a Voltage controlled Oscillator (VCO). The Phase frequency detector used here has been implemented with True Single Phase Clocked logic (TSPC) D flip-flop. This PFD is used to increase the locking performance and to reduce the dead zone. Charge pump is used for the DC-DC conversion. The proposed charge pump avoids charge injection, clock feed through effects and this reduces the ripples in the output. Ring oscillator is used as Voltage Control Oscillator which requires less layout area and has a wide frequency tuning range. Supply voltage of 3V is used and the power dissipated is 11.409 mW. TSMC 0.35- µm technology is used to implement the proposed phaselockedloop.
The objective of this thesis is to design and implementation of different types of charge pump based on performance factors namely speed, power and output voltage, output current, voltage conversion. This thesis provides the comparative study of design and implementation of Dickson charge pump, static charge pump, dynamic charge pump, charge pump with CTS control scheme, charge pump with cross connected NMOS cells. The core objectives are, to study about charge pump importance and existence of these devices in low power and high speed system, design and implementation of different types of charge pump and the comparative study of design and implementation of charge pump.
In this paper, a radical step is taken to remove the phaselockedloop and synchronize the inverter with the grid itself without the need of a dedicated phaselockedloop. Sincethe synchronous machine is inherently able to synchronize with the grid, itis possible to integrate the synchronization function into the power controller. It can automatically synchronize with the grid before connection and track the grid frequency after connection. This leads to a compact control structure. The self-synchronizationcapability ofsynchronverter will remove the major nonlinear element in the controller that affects the speed of synchronization. This improves the speed of synchronization, reduces the complexity and computational difficulty of thePLL and reduces the cost of controller. Hence all the functions of synchronverter suchas frequencyregulation, voltage regulation,real power control and reactive power control can be done without the need of dedicated phaselockedloop. The closest work in this direction is , where no PLL is needed during normal operation; but, a backup PLL is required before connection.
Optical phase-locked loops (OPLL) are used in many applications involving frequency stabilization of a laser, clock extraction in high-speed optical communication systems, low noise microwave or mm-wave signal generation, and precise optical measurements. In the last few years, lot of works has been carried out on OPLL and in connection to its different applications. A balanced OPLL used for clock recovery at a bit rate of 160 Gbps was suggested and experimentally demonstrated . Zibar et al. , analyzed a balanced OPLL used for clock extraction from high-speed optical time division multiplexed (OTDM) signals. The effects of loop-delay time and the laser transfer function were included in the differential equations describing the system, and a detailed timing jitter analysis was performed. A coherent receiver based on an OPLL for linear phase demodulation was presented . For high-frequency operation, monolithic and hybrid integrated versions of the receiver were developed and experimentally verified in an analog link. Also, a novel phase-locked coherent optical phase demodulator with feedback and sampling was proposed and investigated for high-linearity microwave photonic links . A novel coherent optical receiver based on an OPLL was presented and experimentally demonstrated to reduce the nonlinear distortion in a traditional receiver while retaining the signal to noise ratio (SNR). Up to 15-dB of spur free dynamic range (SFDR) improvement was obtained . A high dynamic range phase modulated optical link using an attenuation-counter propagation photonic phase-lockedloop (ACP-PPLL) was reported . A modified OPLL that incorporated a frequency discriminator was proposed  to increase the frequency acquisition capability. Also, an OPLL incorporating a frequency down-conversion module was proposed and demonstrated . The use of the frequency down-conversion module allows the use of lower-frequency components in the phasecontrol module, which would reduce significantly the system cost. A packaged semiconductor laser OPLL for photonic generation, processing and transmission of microwave signals was implemented . Microwave carriers in the range of 7-14 GHz were generated with a phase-error variance of 7 10 4 rad 2 in a 15-MHz bandwidth and 0.4 ns loop-delay condition. Also, a high purity mm-wave optical-beat signals at frequencies up to 330.566 GHz was generated .
Charge Pump is used to produce a charge proportional to the error signal. The function of a charge pump and loop filter is to take the digital UP and DOWN pulses from the PFD and convert them into an analog control voltage, Vcntrl.The charge pump consists of two switched current sources that are used to pump charge into or out of loop filter. Whenever the reference signal leads the feedback signal the PFD detects the rising edge on the reference signal and produces an up signal. This up signal from the PFD turns on the up switch in the charge pump and injects current into the loop filter. Whenever the feedback signal leads the reference signal the PFD detects the rising edge on the feedback signal and produces an Down signal. This Down signal from the PFD turns on the Down switch in the charge pump and sink current from the loop filter. The current through the UP switch, I up , and the current through the down switch,
A PLL is a feedback system made of three elements: a phase detector, a loop filter and a high performance voltage controlled oscillator (VCO). To achieve the layout of proposed PLL, CMOS circuit of each element of proposed PLL is converted into physical layout. For that, lambda based rules of microwind software are used. After cascading the layout of each small device, final layout is obtained. This paper particularly focuses on analysis and design of phaselockedloop with low power consumption using VLSI technology.
From the continuous survey it is observed that foundry of technology and supply voltage range is continuously decreases with the advancement of technology. Phase-lock loop with 0.35- m CMOS technology at a supply voltage of 1.8 V has been designed in 2002.Chen and Sheen presented a phase-lockedloop for clock generation that consists of a phase/frequency detector, charge pump, loop filter, range-programmable voltage-controlled ring oscillator, and programmable divider. Circuits as having low power dissipation, is widely adopted. The modified phase detector and charge pump have been extensively used to enhance the performance of the PLL. By applying the TSMC 0.35- m CMOS technology, the proposed phase-lockedloop that uses the power-switch scheme can yield clock signals ranging from 103 MHz to 1.02 GHz at a supply voltage of 1.8 V. Moreover, power dissipation that is proportional to the number of paralleled inverter rings is measured with 1.32 to 4.59 mW. By using the TSMC 0.35- m CMOS technology, the designed PLL using the power-switch scheme can generate clock frequencies ranging from 103 MHz to 1.02 GHz with a power dissipation ranging from 1.32 to 4.59 mW, at a supply voltage of 1.8 V. [Chen and Sheen, 2002]
Abstract -We model and simulate an analog phase-lockedloop for frequency hopping spread spectrum based applications such as Bluetooth. The modeling and simulation method uses an analog phase-lockedloop, consisting of multiplier, loop filter, voltage controlled oscillator and generates hopping carriers up to 2.502 GHz. The generated carrier frequency holds at a particular hop for a maximum dwell time of 50µS. The complete simulation program for the system is written in Turbo C. The MATLAB program is used for graphical analysis of simulated data. The simulation results show that the generated carriers settle around 60 µS for maximum hopping carrier frequency of 100 MHz. The measured carrier frequencies and settling times are found comparable with standard values and related works.
PFD compares the incoming signal with the PLL output and generate the phase or frequency difference as an error signal. The PFD circuit should consume low power and have a minimum dead zone. Dead zone is a region wherein a PFD fails to detect small frequency/phase errors. This corresponds to one of the sources for jitter. This occurs when there is very small phase difference between the reference signal and VCO output signal. The PFD is designed using 15 transistor and eliminate the reset path. So, power consumption and jitter are reduced in this design.
negative for all negative phase differences. This property gives the PFD its frequency discrimination ability. The sign continuity means that the loopcontrol action for a certain frequency difference is always in the same direction. If the characteristic would have additional zero-crossings, the loopcontrol action would also be zero for multiple points. That would mean that there are multiple frequencies on which the PLL could lock. One of the things that makes PLLs useful is the ability to uniquely control the output frequency. Having multiple lock frequencies would mean a loss of this ability. The loop filter suppresses high frequencies and gives the necessary degrees of freedom to stabilise the loop. Together with the PFD and CP an integrator is formed. This is important for the steady-state phase error, which will be discussed in section 2.1. The Voltage Controlled Oscillator (VCO) is a tunable frequency synthesizer that can provide the desired gigahertz output range.
The R divider allows the input reference frequency to be divided down to produce the reference clock (CLK) for the PFD. It has a wide range of division ratio from 1 to 16383. The N divider is a 13-bit counter and has division ratios from 1 to 8191 . The PFD compares the phase and frequency of the signal from R and N divider. It produces an output control signal proportional to the phase and frequency difference between them. The on-chip registers of the synthesizer can be programmed externally by using serial peripheral interface (SPI) through writing to CLK, DATA and latch enable (LE) control of the device. The maximum allowable CLK rate of the device is 20MHz. The system is interfaced to personnel computer (PC) through 8085 µP via RS232 for writing data to the device. The synthesizer includes a 24-bit shift register where the data is clocked down on each rising edge of the signal. Initially, the data is clocked with most significant bit (MSB) and transferred from the shift register to one of the four latches available in the device on the rising edge of latch enable (LE). The destination latch is determined by the state of the two least significant bits (LSB) in the shift register. An external parallel tank circuit consisting of an inductor and a capacitor is used with the VCO to adjust the frequency. The varactor diode (MMBV609) with a parallel inductor is connected into the tank circuit to provide a voltage variable capacitance for the input of the VCO. These components have direct impact on the tuning sensitivity and PN. The quality factor (Q) of the tank circuit has direct impact on the resulting PN of the oscillator . Therefore, the Q is kept high for lower PN in the oscillator. The typical operating frequency of the VCO is 1100MHz.
Another option is to despread the RF signal using the squarer (in the analog do- main), and perform carrier estimation digitally, through sampling and algorithms. Because the sampling happens not at the front-end, but at the LFO frequency, the sampling rate is considerably lower, and requires considerably less power. Digital phase-locked loops were analyzed in . Phase acquisition was found to be complete within an impressive 11 cycles of the incoming signal frequency. However, this only holds for a noiseless signal. Furthermore, faster acquisition is attained through using higher frequencies, which once more requires sampling on higher frequencies. Although the digital PLL is promising for the application under consideration (fast acquisition), we chose to focus on analog PLLs, because the analog solution might also provide fast acquisition, and does not require digital resources such as memory elements, making the receiver simpler and more energy-efficient. When the TR receiver first despreads the signal through squaring, and subsequently phase-locks by means of a PLL, it es- sentially operates as a coherent receiver. In a coherent receiver, the received signal is multiplied with a local oscillator whose phase is synchronized to that of the received signal. The PLL is the circuit that locks the phase (and frequency) of a local oscillator to that of the incoming signal. In the next section, we will detail the operation of a phase-lockedloop, and analyze the time required for it to enter phase-lock, which is part of the synchronization time for a FODMA receiver. The second part of synchro- nization, symbol-timing estimation, will be discussed in Chapter 5, Section 5.2 as it is part of the synchronization time for both systems.
loop gain should be one and phase of loop gain should be unity ( the feedback network introduces 180 0 phase shift, the other 180 0 phase shift is provided by mixer ) is called Barkhausen criterion”. In VCO 10 the frequency of oscillation is varied by the applied input DC voltage. When there is no input voltage, the output of the VCO will have a frequency called “free oscillation frequency”.It has an integratorfunction for the phase input signal. VCO which is designed in the present work is using the differential- ring oscillator. The gain of the VCO is denoted by K VCO and the gain of the K VCO designed is about 300MHz/V. The Figure5.depicts the schematic
Static phase offset (SPO) in conventional multiplying delay-locked loops (MDLLs) dramatically degrades the deterministic jitter performance. To overcome the issue, this paper presents a new SPO reduction technique for MDLLs. The technique is based on the observation that the SPO of MDLL is mainly caused by the non-idealities on charge pump (e.g. sink and source current mis- match), and control line (e.g. gate leakage of loop filter and voltage controlled delay line (VCDL) control circuit). With a high gain stage inserting between phase detector/phase frequency detec- tor (PD/PFD) and charge pump, the equivalent SPO has been decreased by a factor equal to the gain of the gain stage. The effectiveness of the proposed technique is validated by a Simulink mod- el of MDLL. The equivalent SPO is measured by the power level of reference spur.
and/or the framework capacity by exploiting spatial domain. As of late space-time coded OFDM systems have been receiving far reaching attention. A space-time-frequency coded OFDM framework which accomplishes greatest diversity is proposed. Space-time codes have been intended for use with OFDM over frequency selective fading channels and can accomplish spatial diversity technique by using multiple antennas at the transmitter and receiver. The technique is promising, since it doesn't increase the transmit control and the signal bandwidth. This can be efficiently used through STBC MIMO-OFDM systems. Be that as it may, the above schemes require some side information to be transmitted to the receiver with high unwavering quality, which lessens the ghastly efficiency.
of the ripple current which is due to the current hysteresis control window. Although choosing a very small hysteresis error window width would result in a low THD, it would require a very high switching frequency or a very large filter inductor. So there’s a trade-off between to minimizing the THD, keeping the switching frequency within feasible values to limit the switching losses and maintaining the inductor with a compact size, .
This paper presents a glitch free NAND based digitally controlled delay lines for the avoidance of glitches by using different driving circuits. In glitch free NAND based DCDL, driving circuits are used to generate the control bits which consumes considerable amount of power and delay time. Driving techniques suggested here are dual edge triggered sense amplifier based flip-flop and NIKOLIC sense amplifier based flip-flop, which comparatively have reduced power consumption and delay time. The proposed NAND based DCDL have been designed in 90nm CMOS technology and various performances of these techniques are compared by the simulation parameters like power, area and delay. In addition, the proposed DCDL is adopted in phaselockedloop.