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In this paper, a novel parallel-coupled quadrature LC oscillator (PC-QO) is presented that can automatically eliminate imbalances of output phase and amplitude resulting from mismatches in the LC tanks. The method of using unequal coupling factors in a parallel-coupled quadrature oscillator is the base of this design; canceling the phase and amplitude errors takes place by tuning the imbalanced coupling factor using tuneable tail currents. First, the proposed circuit senses the amplitude error and then adjusts the coupling factors according to the situation. We show that using the inversely proportional coupling factors can eliminate the phase and amplitude error simultaneously. In other words, this design uses the amplitude control loop to cancel the phase and amplitude error. The circuit has been simulated using TSMC 0.18 CMOS practical model to confirm the high accuracy of the analysis and capability of the canceling I / Q mismatch technique. The simulation results show that the phase noise of the proposed quadrature voltage controlled oscillator (QVCO) is −123.9 dBc/Hz at 1 MHz offset from 4.4 GHz operation frequency. The total power consumption of the QVCO is 3.4 mW. [ABSTRACT FROM AUTHOR]

Summary: In this article, an injection‐locked frequency divider (ILFD) is presented. By assuming the maximum phase of the tank current, we obtain a relation for the lock range. Besides, the effects of parasitic capacitors on the lock range have been probed. The analysis shows that the greater the phase difference between the tail current and injected signal, the phase of the tank current increases and, consequently, the lock range also increases. The accomplished simulations confirm the correct performance of the proposed design and the extracted relationships. The simulations have been CMOS technology and with a 0.9‐V supply voltage. The results show that the current consumption equals 3.7 mA and the power consumption equals 3.33 mW. The proposed ILFD lock range with phase shift technique with power input signal 0 dBm is equal to 5.1 GHz (3.6–8.7 GHz), and the relative percentage of the lock range is also 83%. [ABSTRACT FROM AUTHOR]

Summary: This study developed a local oscillator (LO) with low phase noise and low power consumption. The proposed oscillator core comprises a pair of cross‐coupled transistors, which are fed by another pair of transistors that injects current at moments close to the peak of output voltage. The position of the current injection transistors, which are inserted in series with the cross‐coupled transistors, affects the waveform of current injected into an inductive–capacitive (LC) tank. Installing a capacitor on the source node of the cross‐coupled transistors increases the current injected into the LC tank and thereby augments the output voltage amplitude and power efficiency of the LO. The resonator phase shift and Q can be corrected by adjusting the source capacitance, which filters noise. These changes reduce the phase noise to −123.4 dBc/Hz at a frequency offset of 1 MHz and improve oscillator performance with a figure of merit equal to −193.5 dBc/Hz. To evaluate the LC tank, a 5 GHz LO was simulated at 1.8 V power supply and 2.5 mW power consumption. The simulation was conducted using a practical 0.18 complementary metal–oxide–semiconductor model manufactured by the Taiwan Semiconductor Manufacturing Company. The simulation results confirmed the analytical findings. [ABSTRACT FROM AUTHOR]

In this paper, an analytic approach for the estimation of the phase and amplitude error in series coupled LC quadrature oscillator (SC-QO) is proposed. The analysis results show that imbalances in source voltage of coupling transistor because of mismatches between LC tanks are the main source of the phase and amplitude error in this oscillator. For compensation of the phase and amplitude error, a phase and amplitude-tunable series coupled quadrature oscillator is designed in this paper. A phase shift generation circuit, designed using an added coupling transistor, can control the coupling transistor source voltage. The phase and amplitude error can simply be controlled and removed by tuning the phase shifter, while this correction does not have undesirable impact on phase noise. In fact, the proposed SC-QO generates a phase shift in the output current, which reduces the resonator phase shift (RPS) and improves phase noise. The phase and amplitude tunable SC-QO is able to correct the phase error up to ±12°, while amplitude imbalances are reduced as well. To evaluate the proposed analysis, a 4.5-GHz CMOS SC-QO is simulated using the practical 0.18-μm TSMC CMOS technology with a current consumption of 2 mA at 1.8-V supply voltage. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents the design and analysis of phase-tunable injection-coupled quadrature oscillator (PT-IC-QO). Like other LC QOs, the mismatches between LC tanks are the main source of phase error in this oscillator. Using tail current in network coupling is novel approach to design new IC-QO. One of the advantages using added extra tail current in coupling network is control of coupling factor and also that it drastically reduces supply noise over classic IC-QO. Analysis and simulation result show that phase error can be controlled and cancelled simply by using tunable tail current in network coupling while that is difficultly controlled in the previse work. The basic idea of the presented design to reduce phase error due to tank mismatches is its compensation with an intentional mismatch between $$I\hbox {/}Q$$ -side injection current. Based on the equations, a new tunable source-injected QO is proposed which is able to cancel the phase errors up to $$\pm 20^\circ $$ , without undesirable impact on phase noise. To evaluate the proposed analysis and consequent designed quadrature oscillator, a 5.4-GHz CMOS PT-QO is designed and simulated using the practical $$0.18\,\upmu \hbox {m}$$ TSMC CMOS technology. [ABSTRACT FROM AUTHOR]

In this paper, a new method for computing the amplitude and frequency of differential ring oscillators (ROs) is proposed. The analysis is performed in two separate parts. In the first of these, equations are derived with the assumption of a sinusoidal waveform of outputs, while in the other, the outputs are assumed to be exponential. It is shown that the derived equations for frequency and amplitude are sufficiently exact. In addition, conditions in which sinusoidal and exponential output occur are thoroughly discussed. In the instances in which the results did not satisfy the necessary conditions for sinusoidal output, the output is assumed to be exponential. Moreover, the related analytical equations are written, and the new expressions for frequency and amplitude of ROs are derived. Analytical results are confirmed by simulation results, using the Taiwan Semiconductor Manufacturing Company 0.18 µm technology model. The simulation results indicate the high level of accuracy of the proposed model. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach to study the phase error in source injection coupled quadrature oscillators (QOs). Like other LC QOs, the mismatches between LC tanks are the main source of phase error in this oscillator. The QO is analyzed where the phase error and oscillation frequency are derived in terms of circuit parameters. The proposed analysis shows that the output phase error is a function of injection current and the current of source equivalent capacitor. As a result, it is shown that increasing of tail current and LC tank quality factor decreases the phase error. Derived equations show that the phase error can be cancelled and even controlled by adjusting bias currents. To evaluate the proposed analysis and consequent designed QO, a 5.5 GHz CMOS QO is designed and simulated using the practical 0.18 µm TSMC CMOS technology. The experiments show good agreement between analytical equations and simulation results. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, a novel LC quadrature oscillator (QO) is presented that can simply and automatically cancel the phase and amplitude errors raised by mismatches in LC tanks; the major source of phase and amplitude errors. The design is based on method of using unequal coupling factors in a parallel quadrature oscillator (P-QO). This method shows how we can cancel phase and amplitude errors simultaneously by choosing appropriate inversely proportional coupling factors. To cancel the errors, the proposed circuits first sense the phase error and increase or decrease the difference between the coupling factors accordingly. When tuning tail currents, the coupling factors can be simply adjusted. The entire system has a block diagram like a PLL. The dynamics of the proposed circuit is analyzed, and it is shown how the phase and amplitude error is canceled in response to an imposed LC tank mismatch. To evaluate the circuit, a QO has been designed to oscillate at 5 GHz with 1.8 V supply and 6.2 mA current consumption. The circuit has been simulated using TSMC 0.18 CMOS practical model where all the results confirm the analytical results. [ABSTRACT FROM AUTHOR]

In this article, closed-form equations are proposed for phase and amplitude errors of an in-phase coupled quadrature LC oscillator. First of all, the injected current from coupling network to switching one is analytically calculated in a novel approach. Then, fundamental equations are obtained to derive phase and amplitude errors which are results of mismatches of the tank's inductors, capacitors and resistors. The analysis shows that the LC tank's phase of this oscillator has a negligible deviation from zero that is desirable and causes low phase noise. Also, the study indicates that in-phase coupling of this structure generates an injection current that reduces the output current magnitude. In the following, a mechanism is proposed to compensate the phase error, using intentional mismatch in tail currents. Moreover, In contrast to previous works, there is not a considerable trade-off between phase error and phase noise; meaning phase noise is almost stable while phase error dramatically decreases. Next, Many simulations have been done in TSMC 0.18 μm to evaluate the proposed analytical equations and efficiency of the presented approach. Finally, all of these tests confirm the high accuracy of equations and capability of the mentioned technique. • This article presents information about why in-phase coupling is useful. • This article provides novel technique to calculate phase and amplitude error of an IPC-QO to predict its behaviour. • This article presents an idea to compensate the phase error of the IPC-QO, while phase noise is still stable. • Scientists who work with all types of LC oscillators, in all of transceivers, can benefit from this article. [ABSTRACT FROM AUTHOR]