A novel superharmonic coupling topology for quadrature oscillator design at 6 GHz

Hancock, Timothy; Rebeiz, Gabriel M.

doi:10.1109/rfic.2004.1320597

Cited by 32 publications

(62 citation statements)

References 12 publications

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“…1 (c). Further simulations using a wide variety of the circuit parameter values revealed that these circuits [6,7] oscillate in-phase and generate quadrature outputs only for a limited region of circuit elements values, a behavior in contrast to those of [4,5] in which almost always generated quadrature outputs.…”

Section: Superharmonic Coupling Mechanisms and Quadrature Robustnessmentioning

confidence: 94%

“…1 and the common mode node pairs in these circuits are denoted with (a, a ), (b, b ), and (c, c ). As can be easily verified, presence of a 180 • phase difference between the current and/or voltage signals at the common mode nodes of each of the core oscillators, results in 90 • phase differences in the first harmonic components of the output signals [3,4,5,6,7,8,9]. The 180 • phase difference can be provided with a transformer.…”

Section: Superharmonic Coupling Mechanisms and Quadrature Robustnessmentioning

confidence: 95%

“…However, the on-chip transformer occupies large chip area and its limited quality factor can cause degradation of the phase-noise. coupling ( [4,5]), (c) with direct coupling [7].…”

Section: Superharmonic Coupling Mechanisms and Quadrature Robustnessmentioning

confidence: 99%

“…In the QVCO proposed in [5], to save the chip area, the transformer is replaced with a cross-connected differential pair and in this way 180 • phase difference is enforced between the second harmonics of V b and V b (Fig. 1 (b)).…”

Section: Superharmonic Coupling Mechanisms and Quadrature Robustnessmentioning

confidence: 99%

“…Depending on their mechanism of operation, LC-QVCOs can be categorized in two main groups: first harmonic QVCOs [2] and superharmonic QVCOs [3,4,5,6,7,8,9]. In most of the QVCOs in the former group, oscillation frequency deviates from the LC-tank resonance frequency, leading to phase-noise degradation [11].…”

Section: Introductionmentioning

confidence: 99%

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New capacitive coupled superharmonic quadrature LC-VCO

Ebrahimi

Naseh

2010

IEICE Electron. Express

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Abstract:A study of some reported LC quadrature voltagecontrolled oscillators (LC-QVCO) is performed in which it is shown that robustness of the quadrature oscillation varies depending on the coupling configuration. Next, a new superharmonic LC-QVCO is proposed in which the common source node in either of two identical crossconnected LC-VCOs is coupled via a capacitor to the node common between the two varactors in the LC tank of the other LC-VCO. In the proposed coupling configuration there exists a closed loop through which the second harmonic signals circulate. A qualitative argument is presented to justify the robustness of the quadrature nature of the proposed QVCO by applying the Barkhausen phase criterion to the second harmonic signals in the loop. Since the coupling devices are only two capacitors, no extra noise sources and power consumption are added to the core VCOs. A Monte Carlo simulation showed that the phase error of the proposed QVCO is no more than 1 o . Also, generalizing this method to several numbers of VCOs in a loop, multiphase signals can be generated. The proposed circuits were designed using a 0.18-μm RF CMOS technology and simulation results are presented.

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Section: Superharmonic Coupling Mechanisms and Quadrature Robustnessmentioning

confidence: 94%

Section: Superharmonic Coupling Mechanisms and Quadrature Robustnessmentioning

confidence: 95%

“…However, the on-chip transformer occupies large chip area and its limited quality factor can cause degradation of the phase-noise. coupling ( [4,5]), (c) with direct coupling [7].…”

Section: Superharmonic Coupling Mechanisms and Quadrature Robustnessmentioning

confidence: 99%

Section: Superharmonic Coupling Mechanisms and Quadrature Robustnessmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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New capacitive coupled superharmonic quadrature LC-VCO

Ebrahimi

Naseh

2010

IEICE Electron. Express

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Phase noise analysis of source injection coupled quadrature oscillator

Azizi

Abbasalizadeh

Naimi

2020

Circuit Theory & Apps

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This paper analyzes the thermally induced phase noise and the up-conversion of flicker noise into phase noise of source injection coupled quadrature oscillator (SIC-QOSC), for the first time. Furthermore, this paper provides a complete analysis for the injection current of the SIC-QOSC and extracts the closed-form expressions for it for the first time, too. These expressions lead to obtaining the harmonics of the injection current as well as the oscillation amplitude, which is necessary for the phase noise analysis. To evaluate the extracted equations, this paper compares the calculated results with appropriate simulations. Comparisons confirm the accuracy of the proposed injection current expressions and the phase noise formulas. Using the closed-form equations of phase noise, designers can understand the SIC-QOSC's design tradeoffs and design the oscillator for given phase noise. K E Y W O R D SAdler equation, injection current, source injection coupled quadrature oscillator (SIC-QOSC), thermal phase noise, flicker noise

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Quadrature VCOs based on direct second harmonic locking: Theoretical analysis and experimental validation

Tortori

Guermandi

et al. 2010

Circuit Theory & Apps

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SUMMARYWe propose a theoretical analysis of the class of quadrature VCOs (QVCOs) based on two LC-oscillators directly coupled by means of the second harmonic. The analysis provides the conditions for the existence and stability of steady-state quadrature oscillations and a simplified model for the phase noise (PN) transfer function with respect to a noise source in parallel to the tank. We show that the figure of merit defined as the product between PN and current equals that of the single VCO, confirming that quadrature generation is achieved by this class of QVCO without degrading that figure of merit. An analytical model for the phase quadrature error due to tank mismatches is also proposed. The validity of all analytical models is discussed against numerical simulations. A practical implementation at 3.26 GHz with ±20% tuning range in a 0.13 m CMOS technology is also presented, confirming the main theoretical findings.

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A novel superharmonic coupling topology for quadrature oscillator design at 6 GHz

Cited by 32 publications

References 12 publications

New capacitive coupled superharmonic quadrature LC-VCO

New capacitive coupled superharmonic quadrature LC-VCO

Phase noise analysis of source injection coupled quadrature oscillator

Quadrature VCOs based on direct second harmonic locking: Theoretical analysis and experimental validation

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