Quadrature Oscillator Research Articles

Quadrature Sinusoidal Oscillators Using CDBAs: New Realizations

Four new circuits of fully uncoupled quadrature sinusoidal oscillators, using two current differencing buffered amplifiers (CDBAs), four/five resistors and two capacitors have been presented. In contrast to all previously published CDBA-based, fully decoupled, quadrature sinusoidal oscillators in which one of the input terminals is left unutilized, the presented circuits are realized by utilizing the intrinsic current differencing property of CDBAs, thus utilizing all the four terminals of the CDBA. All these quadrature oscillator (QO) circuits have an inherent feature of amplitude control of output voltages without using external control circuitry. Out of the four proposed QO circuits, two circuits have the additional feature of generating low-frequency oscillations, thus making them capable of generating wide range of frequency waveforms. The proposed oscillator circuits also possess additional functionalities not available in other CDBA-based quadrature sinusoidal oscillator circuits presented previously. The workability of the proposed circuits has been confirmed through experimental results where CDBAs are implemented using commercially available current feedback operational amplifiers (AD844).

Source injection coupled quadrature oscillator: transient oscillation amplitude and thermally induced phase noise

This paper analyzes the transient oscillation amplitude of the source injection coupled quadrature oscillator (SIC-QOSC). With the help of the Describing Function Method, we estimate an expression to describe the nonlinear behavior of the negative transconductor. Using the estimated expression, we obtain an accurate closed-form formula for the time-domain amplitude of the SIC-QOSC. The proposed formula could be useful for designers to analyze the transient behavior of the SIC-QOSC. This aspect of SIC-QOCS has not studied yet. Also, this paper analyzes the thermally induced phase noise of the SIC-QOSC. For this purpose, we use the weak injection method. Using the extracted formulas, designers can understand the design tradeoffs to design an optimum SIC-QOSC. To evaluate the validity of the extracted formulas for the transient oscillation amplitude as well as the phase noise, we compare the calculated results with the appropriate simulations. Simulations have been done in 0.18 µm CMOS technology with a 1.8 V supply voltage. We reached a good agreement between the simulations and our analytical results.

Analytical Synthesis of High-Pass, Band-Pass and Low-Pass Biquadratic Filters and its Quadrature Oscillator Application Using Current-Feedback Operational Amplifiers

In this paper, a method of realizing voltage-mode (VM) non-inverting high-pass filter (HPF), band-pass filter (BPF), low-pass filter (LPF), and inverting low-pass filter (ILPF) transfer functions structure with two grounded capacitors and four resistors through an analytical synthesis method is presented. The synthesis structure of the VM biquadratic filter consists of a voltage proportional block and two voltage lossless integrators based on the use of current feedback operational amplifiers (CFOAs). It is demonstrated that the derived biquadratic filter structure can simultaneously realize VM HPF, BPF and ILPF transfer functions or VM BPF and LPF transfer functions at a high-input impedance terminal. The VM biquadratic filter can independently adjust the resonance angular frequency and quality factor. By slightly modifying the proposed biquadratic filter, a VM quadrature sinusoidal oscillator can be achieved. The proposed biquadratic filter and quadrature oscillator have been simulated by OrCAD PSpice and appropriate hardware has been implemented with AD844-type CFOAs. In order to reduce power consumption, reduce chip area, reduce costs, and improve system integration, integrated VM CFOA-based biquadratic filter circuits and quadrature oscillator circuits are very important. The proposed filter and quadrature oscillator have been further fabricated in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.18~\mu \text{m}$ </tex-math></inline-formula> 1P6M CMOS process technology. The entire chip area is 0.974 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , including a filter chip cell and an oscillator chip cell. Under the supply voltage of ±0.9 V, the total power dissipation of the filter chip cell is 5.4 mW, and the figure-of-merit (FOM) of filter chip cell is 66.7%. The measured value of the third-order intermodulation distortion of the filter chip cell is −55.29 dBc and the third-order intercept point is 19.9 dBm. The measured phase noise of CFOA-based filter chip cell at 1 kHz offset is less than −99.76 dBc/Hz.

Multiple-Input Universal Filter and Quadrature Oscillator Using Multiple-Input Operational Transconductance Amplifiers

This paper presents a new multiple-input single −output voltage-mode universal biquad filter based on multiple−input operational transconductance amplifiers (MI-OTA). This work demonstrates that the multiple-input OTA−based universal filter can provide more filtering responses and other benefits, compared to conventional OTA−based one. The filter provides electronic and orthogonal control of the natural frequency and the quality factor. Furthermore, a two-phase quadrature oscillator can be obtained by slightly modifying the proposed universal filter while the condition and frequency of oscillation can be controlled orthogonally and electronically. The performance of the proposed circuit is evaluated in Cadence environment using the TSMC $0.18~\mu \text{m}$ CMOS technology. The voltage supply is 1.2 V and the power dissipation of the MI−OTA is $24~\mu \text{W}$ . For 1% third intermodulation distortion (IMD3) the dynamic range of the band−pass filter is 78.6 dB. In addition, the proposed filter and oscillator are investigated through experiment tests using LM13700 commercially available OTA.

Voltage-Mode Multifunction Biquad Filter and Its Application as Fully-Uncoupled Quadrature Oscillator Based on Current-Feedback Operational Amplifiers

This research introduces a new multifunction biquad filter based on voltage mode (VM) current-feedback operational amplifier (CFOA) and a fully uncoupled quadrature oscillator (QO) based on the proposed VM multifunction biquad filter. The proposed VM multifunction biquad filter has high impedance to the input voltage signal, and uses three CFOAs as active components, while using four resistors and two grounded capacitors as passive components. The VM CFOA-based multifunction biquad filter realizes band-reject, band-pass, and low-pass transfer functions at high-input impedance node simultaneously, which has the feature of easy cascading in VM operation without the need for additional voltage buffers. Additionally, the filter control factor parameter pole frequency (ωo) and quality factor (Q) of the proposed VM multifunction biquad filter can be independently set by varying different resistors. By slightly modifying the VM multifunction biquad filter topology, a VM fully-uncoupled QO is easily obtained. The difference from the previous VM CFOA-based multifunction biquad filter is that the proposed VM CFOA-based multifunction biquad filter can be independently controlled by the filter control factor parameters, ωo and Q. The proposed VM CFOA-based multifunction biquad filter can be transformed into a VM QO with fully-uncoupled adjustable of the oscillation condition and the oscillation frequency. The oscillation condition and the oscillation frequency can be fully-uncoupled and controlled by varying two sets of completely different resistors. The proposed VM fully-uncoupled QO solves the amplitude instability. The constant amplitude ratio of two quadrature sinusoidal waveforms can be realized when tuning FO. PSpice simulation and experimental results prove the performances of the proposed VM multifunction filter and VM fully-uncoupled QO. Simulation and experimental results confirm the theoretical analysis of the proposed circuits.

Single VDGA-Based Dual-Mode Multifunction Biquadratic Filter and Quadrature Sinusoidal Oscillator

This article relates to the realization of voltage-mode and/or current-mode multifunction biquadratic filter and quadrature oscillator circuits each using one voltage differencing gain amplifier (VDGA), two resistors and two grounded capacitors. The proposed dual-mode filter having one output and three inputs can provide the three standard biquadratic transfer functions with both voltage and current output filter responses simultaneously. It also has the independent tuning of the angular resonance frequency and the quality factor . With a slight modification of the proposed filter, a new dual-mode quadrature sinusoidal oscillator can be obtained. The proposed quadrature oscillator provides orthogonal resistive/electronic control of both oscillation condition and oscillation frequency. Non-ideal and parasitic conditions are also examined and their effects on the circuit performance are discussed. In order to confirm the theory, several computer simulation results with PSPICE program are given .

Electronically tunable third-order dual-mode quadrature sinusoidal oscillators employing VDCCs and all grounded components

Two new configurations of third-order dual-mode (i.e. both voltage and current mode) quadrature sinusoidal oscillator using a newly reported active block, called the voltage differencing current conveyor (VDCC) have been presented in this manuscript. Both the proposed oscillators employ two VDCCs, three capacitors, and three resistors. The circuits are suitable for integrated circuit (IC) realization as all the passive components used in the circuits are grounded. In addition, the proposed configurations enjoy the following advantages: i) both the frequency of oscillation (FO) and the condition of oscillation (CO) are electronically tunable; ii) tuning of FO and CO are independent to each other; and iii) active and passive sensitivities are low. Non-ideal, parasitic and phase noise analysis of the circuits have been included to strengthen the design idea. PSPICE simulation results using TSMC 0.18 μm CMOS technology are given to verify the theoretical analysis. The operations of the proposed circuits are also verified experimentally wherein VDCC is realized using OPA860 ICs.

A 28 GHz front-end for phased array receivers in 180 nm CMOS process

In this paper, a receiver front-end in 180 nm CMOS operating at 28 GHz is presented. The receiver front-end consists of a cascade low-noise amplifier (LNA) with two gain stages and a current-bleeding active mixer with tunable loads. By embedding a quadrature coupler into the mixer, the circuit delivers in-phase and quadrature outputs. The proposed architecture avoids the traditional I/Q implementation by process-sensitive quadrature voltage control oscillators (VCOs) with larger power consumption at high frequencies. The adopted transformers and inductors are optimized by a momentum tool. The simulated results show that the receiver front-end provides an NF of 5.48 dB, a conversion gain of 18.1 dB, and an IIP3 around −8.5 dBm at 28 GHz. The circuit dissipates 17.3 mW under a 1.8 V supply.

Versatile Voltage-Mode Biquadratic Filter and Quadrature Oscillator Using Four OTAs and Two Grounded Capacitors

This article presents a versatile voltage-mode (VM) biquad filter with independently electronic tunability. The proposed structure using one dual-output operational transconductance amplifier, three single-output operational transconductance amplifiers (OTAs) and two grounded capacitors was explored to derive a new VM quadrature oscillator with the independent control of the oscillation frequency and the oscillation condition. The proposed versatile VM biquad filter achieves nearly all of the main advantages: (i) simultaneous realizations of band-reject, band-pass, and low-pass from the same architecture, (ii) multiple-input and multiple-output functions, (iii) independent electronic adjustability of quality factor and resonant angular frequency, (iv) no resistor needed, (v) all input terminals with cascade functions, (vi) no additional inverting amplifier for input signals, (vii) using only grounded capacitors, and (viii) easy to implement a VM quadrature oscillator with independent electronically controlled oscillation frequency and oscillation condition. The proposed versatile VM biquad filter employs only four OTAs and two grounded capacitors. The active components of the proposed VM biquad filter are one less than that of recent reports. The proposed circuit also brings versatility and simplicity to the design of VM biquad filters and VM quadrature oscillators. Filters and oscillators with less active and passive components have the advantages of low cost, low power dissipation, low circuit complexity, and low noise. Commercially available integrated circuit LT1228 and discrete components can be used to implement the proposed OTA-based circuits. The simulation and experiment results validated the theoretical analysis.

Analysis and design of a new low‐phase noise and Gm‐enhanced class‐C quadrature VCO

This study presents a new low-power and low-phase noise Colpitts quadrature voltage-controlled oscillator (QVCO). The proposed QVCO contains two differential Colpitts voltage-controlled oscillators (VCOs) that use gain-boosting technique to enhance the negative transconductance and relax start-up condition. Both switching and tail transistors are configured in class-C to improve impulse sensitivity function and phase noise performance of the circuit via better noise modulation function. In addition, flicker noise would be reduced because of the switched-biasing mechanism of tail transistors. Phase noise analysis shows that changing the bias voltage of switching as well as tail transistors can improve the phase noise performance of the core VCO with overlap reduction of the transistors active time. Consequently, due to no extra noisy elements for coupling and class-C biasing of all transistors, low-phase noise quadrature signals are generated. To verify the performance of the proposed technique, post-layout simulation is performed in Taiwan Semiconductor Manufacturing Company (TSMC) of 0.18 μm Radio Frequency-Complementary Metal-Oxide- Semiconductor (RF-CMOS) process at a supply voltage of 1.2 V. Post-layout simulation results show that the phase noise of the proposed QVCO is −120.6 dBc/Hz at 1 MHz offset from 5.73 GHz operation frequency. The total power consumption of the QVCO is 3.1 mW and the tuning range is from 5 to 5.73 GHz.

Voltage-mode Second-order Filter and Quadrature Oscillator Based-on Differential Difference Current Conveyors and Only Grounded Elements

Voltage-mode Second-order Filter and Quadrature Oscillator Based-on Differential Difference Current Conveyors and Only Grounded Elements

Various applications of analog signal processing employing voltage differencing current conveyor and only grounded passive elements: a re-convertible approach

A re-convertible circuit that can either act as a current-mode universal filter or as a fully un-coupled dual-mode single-resistance-controlled quadrature oscillator or simply works as a grounded loss-less inductor, by simple selection of appropriate passive switches, is proposed here. The proposed circuit requires a maximum of two voltage differencing current conveyors as an active element in the case of filter and oscillator application, whereas only one active device suffices the purpose of active inductor implementation. In all the cases only grounded passive elements are employed. Various regular analysis for the proposed circuits have also been included here to support the theoretical idea. The workability of these circuits has been demonstrated by practicing PSPICE simulation software with TSMC CMOS 0.18 μm process parameters along with the experimental justification of the derived application using commercially available integrated circuits.

Improved Performance of M-Class PMUs Based on a Magnitude Compensation Model for Wide Frequency Deviations

Phasor measurement units (PMUs) are important elements in power systems to monitor and know the real network condition. In order to regulate the performance of PMUs, the IEEE Std. C37.118.1 stablishes two classes—P and M, where the phasor estimation is carried out using a quadrature oscillator and a low-pass (LP) filter for modulation and demodulation, respectively. The LP filter plays the most important role since it determines the accuracy, response time and rejection capability of both harmonics and aliased signals. In this regard and by considering that the M-class filters are used for more accurate measurements, the IEEE Std. presents different M-class filters for different reporting rates (when a result is given). However, they can degrade their performance under frequency deviations if the LP frequency response is not properly considered. In this work, a unified model for magnitude compensation under frequency deviations for all the M-class filters is proposed, providing the necessary values of compensation to improve their performance. The model considers the magnitude response of the M-class filters for different reporting rates, a normalized frequency range based on frequency dilation and a fitted two-variable function. The effectiveness of the proposal is verified using both static and dynamic conditions for frequency deviations. Besides that, a real-time simulator to generate test signals is also used to validate the proposed methodology.

A new tail-switching superharmonic multiphase LC-VCO

PurposeMultiphase and quadrature voltage-controlled oscillators (QVCOs) play key roles in modern communication systems and their phase noise performance affects the performance of the overall system. Different studies are devoted to efficient quadrature signals generation. This paper aims to present a new low-phase noise superharmonic injection-locked QVCO.Design/methodology/approachThe proposed QVCO is comprised of two identical inductor-capacitor circuit (LC)-voltage-controlled oscillators (VCOs) in which second harmonics, with 180° phase shift, are injected from one core VCO to the gate of tail current source of the other VCO via a coupling capacitor. Using second harmonics with high amplitude will switch the tail from the inversion to the accumulation, and therefore, flicker noise is reduced. Also, because of the use of lossless and noiseless coupling elements, that is, coupling capacitors, and also because of the existence of an inherent high-pass filter, the proposed LC-QVCO has a good phase noise performance.FindingsThe introduced technique is designed and simulated in a commercial 0.18 µm radio frequency complementary metal oxide semiconductor (RF-CMOS) technology and 10 dB improvement of close-in phase noise is achieved (compared to the conventional method). Simulation results show that the phase noise of the proposed QVCO is −130.3 dBc/Hz at 3 MHz offset from 5.76 GHz center frequency, while the total direct current (DC) current drawn from a 0.9-V power supply is 4.25 mA (figure of merit = −190.2 dBc). Monte Carlo simulation results show that the figure of merit of the circuit has a Gaussian distribution with mean value and standard deviation of −189.97 dBc and 0.183, respectively.Originality/valueThis technique provides a new simple but efficient superharmonic coupling and noise shaping method that reduces close-in phase noise of superharmonic multiphase VCOs by switching of tail transistors with 2 ω0 (second harmonic of oscillation frequency). No extra devices such as area-consuming transformer or additional power-hungry oscillator are used for coupling.

An Energy-Efficient 10-Gb/s CMOS Millimeter-Wave Transceiver With Direct-Modulation Digital Transmitter and I/Q Phase-Coupled Frequency Synthesizer

A fully integrated energy-efficient 10-Gb/s millimeter-wave transceiver with direct-modulation digital transmitter (TX) and I/ Q phase-coupled frequency synthesizer in 65 nm CMOS is presented. The transceiver consists of a direct-conversion receiver (RX), a digital TX with on-chip QPSK modulation, and a quadrature local-oscillation (LO) generation network with a 20-GHz phase-locked loop (PLL) frequency synthesizer. A T/R switch is integrated to interface with an E-shaped patch antenna. The QPSK modulation is directly realized in the I/ Q digital power amplifier (DPA), which simplifies the TX complexity and reduces the power consumption. A 20-GHz sub-sampling PLL (SSPLL) and a quadrature phased-coupled injection-locked oscillator (QILO) are integrated on-chip to generate 60-GHz quadrature LO signals. The QILO utilizes in-phase coupling technique to improve the LO I/ Q matching and phase noise performance. The RX achieves 7.1-dB noise figure (NF) and 25- to 47-dB dynamic gain range. The LO phase noise measured at the TX output is -115.6 dBc/Hz at 10 MHz offset from 60 GHz carrier. The measured error vector magnitude (EVM) of the TX is -23.9 dB for 10-Gb/s QPSK signals at 7-dBm output power. The EVM of the over-the-air (OTA) modulation-demodulation system is -13.8 dB for 10-Gb/s QPSK signals. The transceiver achieves the 10-Gb/s data rate while consuming 340.4 mW. The energy efficiency is 34 pJ/bit. This work demonstrates the fully functional wireless link based on the proposed mm-wave transceiver, which highlights the possibility of energy-efficient solution for future high throughputs mm-wave wireless systems.

Electronically Tunable Mixed Mode Quadrature Oscillator Using DX-MOCCII

A new electronically tunable quadrature oscillator is presented using a biquad band pass filter. The new band pass filter is designed using two dual X second-generation multi-output current conveyors (DX-MOCCIIs), two grounded capacitors, two grounded resistors and one NMOS transistor working in the triode region. It is used to design a four-phase voltage and three-phase current output quadrature oscillator simultaneously. The frequency of the oscillator can be tuned externally through the MOS gate voltage without affecting the condition of oscillation. The phase noise, frequency stability and nonideality analysis are given. The functionality of the oscillator circuit has been confirmed by SPICE simulation and also hardware realization using commercially available IC AD844.

On the quadrature accuracy of in-phase coupled quadrature LC oscillator

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.

Generalised approach for active‐RC quadrature oscillator circuit with grounded capacitors

This study introduces a new approach for realising a sinusoidal oscillator with three outputs, using an active-resistor-capacitor (RC) approach. Using the proposed approach, a new circuit employing three current feedback operational amplifiers and passive components is further introduced. The circuit employs two grounded capacitors and four resistors, out of which one is grounded. The new circuit based on the proposed generalised approach is relatively insensitive to the parasitic effects of active elements, and easy to design, by way of non-interaction of frequency and condition of oscillations. The proposed approach and the new proposed circuit provide three outputs, two of which are at low impedance nodes. The proposed generalised approach and the new circuit are verified through simulation and experimental results, using commercially available AD-844s integrated circuits and passive components. Thus, the work advances the existing knowledge on the active-RC oscillator design.

Design of 0.13 µm low power CMOS subharmonic mixer for DCR applications

ABSTRACT This paper presents a design of 2.4 GHz folded subharmonic active mixer in TSMC 130 nm CMOS process for direct conversion receiver (DCR). To achieve the low supply voltage, the folded topology is adopted for the proposed subharmonic mixer. The complementary current reuse structure is used as RF transconductance stage where the biasing for the PMOS and NMOS transistors are self-biased by a resistor to support high conversion gain at low supply voltage. Frequency doubling operation is done by the mixing core which is driven by a quadrature local oscillator (LO) signals. The proposed mixer is designed and simulated using ADS (Advanced Design System) simulator with Cadence software. It produces 10.5 dB conversion gain, a single sideband) noise figure of 9.5 dB, 2 LO-to-RF isolation of 53 dB, LO-to-RF isolation of 117 dB, RF-to-IF isolation of 55 dB and IIP3 of −7.5 dBm. The quadrature LO subharmonic mixer consumes 824μW power from a supply voltage of 0.8 V. The proposed mixer is compared with existing subharmonic mixers. The comparison shows the proposed subharmonic mixer gives a good Figure of Merit.

Analytical Synthesis and Implementation of Low-Frequency Precision Electronically Controlled CFOA – Based Quadrature Oscillator

Analytical Synthesis and Implementation of Low-Frequency Precision Electronically Controlled CFOA – Based Quadrature Oscillator