A low-power, high-frequency, all-NMOS all-current-mirror sinusoidal quadrature oscillator

A low-power, high-frequency, sinusoidal quadrature oscillator is presented through the use of only current mirrors where the small-signal paths are realized through all NMOS transistors. The technique is relatively simple based on (i) inherent time constant of current mirrors, i.e. the internal capacitances and the transconductance of a diode-connected NMOS, (ii) a negative resistance formed by a transconductance of a diode-connected NMOS load of a current mirror. No external passive components are required. As a particular example, a 2.83 GHz, 0.374 f_T, 0.38 mW sinusoidal quadrature oscillator is demonstrated. Total harmonic distortions are less than 0.8%. The oscillation frequency is current-tunable over a range of 640 MHz or 22.62%. The amplitude matching and the quadrature phase matching are better than 0.04 dB and 0.17°, respectively. A figure of merit called a normalized carrier-to-noise ratio is 158.23 dBc/Hz at the 2 MHz offset from 2.83 GHz. Comparisons to other approaches are also presented.     

Dual translinear voltage/current convertor

A new voltage/current convertor (VCCS) using a translinear loop and two current mirrors is described. This convertor has two bipolar outputs, and two different loads can be used. The properties of this convertor are presented for direct current and sinusoidal input signals.     

Electronically tunable sinusoidal oscillator circuit with current and voltage outputs

A new circuit configuration for the realisation of an electronically tunable sinusoidal oscillator is presented. The proposed circuit uses only one current backward transconductance amplifier (CBTA), two grounded capacitors and one resistor. Using current controlled CBTA (CC-CBTA) instead of the CBTA, the resistor can be completely removed. It has also current-mode (CM) and voltage-mode (VM) outputs, simultaneously. The workability of the proposed structure has been demonstrated by both simulation and experimental results.     

A Subthreshold Low Phase Noise CMOS LC VCO for Ultra Low Power Applications

A subthreshold low power, low phase-noise voltage controlled oscillator (VCO) is demonstrated in a commercial 0.18 mum CMOS process. In subthreshold regime, MOS drain current is dominated by diffusion mechanism resulting in a high ratio of transconductance to drain current and suppressed phase noise. Therefore, low power and low phase noise characteristics are achieved without using nonconventional high passive components. The VCO measures a phase noise of -106 dBc/Hz at 400 kHz offset from 2.63 GHz oscillation frequency with 0.43 mW power dissipation drawn from 0.45 V power supply. Figures of merit for this VCO (power-frequency-normalized of 12 dB and power frequency-tuning-normalized of -10 dB) are among the best reported for CMOS oscillators.     

An Amplitude-Balanced Current-Reused CMOS VCO Using Spontaneous Transconductance Match Technique

A 3.5 GHz, 0.18 $mu{rm m}$ CMOS current-reused voltage-controlled oscillator (VCO) with very high amplitude balance is presented. While the current-reused VCO can dramatically save dc power consumption, it has the drawback of output amplitude imbalance resulting from the asymmetric circuit structure. A spontaneous transconductance match (STM) technique is proposed to balance the transconductance of nMOS and pMOS transistors by the imbalance-induced voltage at the center-tapped point of the tank inductor. This transconductance match takes place spontaneously with the occurrence of signal imbalance such that imbalances can be instantly eliminated. The measured amplitude imbalance ratio is less than 0.7% over the entire tuning range of 2.93 to 3.62 GHz, significantly reduced from 3% of the VCO without STM. The power consumption is as low as 1.65 mW from a 1.5 V supply. The phase noise is $-$ 122 dBc/Hz at 1 MHz offset. A very high FOM of $-$195.7 dBc/Hz is achieved.      

Linearly Tunable CMOS OTA With Constant Dynamic Range Using Source-Degenerated Current Mirrors

This brief introduces a new operational transconductance amplifier (OTA) that maintains the input voltage-swing constant during$ gm $adjustments, enabled by employing current mirrors with source degeneration. The OTA presents a wide$ gm $tuning range, which is linearly accomplished through a variable current source. The key design steps are illustrated through an example, and simulation results are included to validate the theory.     

A temperature stabilized CMOS VCO

The established method of frequency drift compensation in voltage controlled oscillators (VCOs) resulting from temperature variance involves modulation of control voltage using a non-linear voltage internally generated. An innovative frequency drift compensation scheme for a VCO, based on amplitude control, is described in this paper. Two peak detectors are used to generate voltages representing positive and negative peaks of the sinusoidal driving an error amplifier. The amplifier output controls the delivery of transconductance accessible to the oscillator, thereby keeping the oscillation amplitude steady. Frequency stability has improved to 16 ppm/°C from an uncompensated value of 189 ppm/°C and is applicable where frequency stability requirements are not stringent, such as HS-USB and S-ATA. The temperature stabilized VCO at 2.4 GHz center frequency is prototyped using CMOS technology from ams AG (formerly austriamicrosystems AG). The result obtained from this study indicates that better frequency stability may be achievable if the traditional compensation scheme is preceded by amplitude control.     

A differential-input,differential-output current mode operational amplifier

A current operational amplifier with differential input and differential output is described. The amplifier is based on the parallel connection of a CCII+ current conveyor and a CCII? current conveyor followed by a differential output transconductance gain stage. The performance of the amplifier is analysed and experimental results obtained from an implementation using standard operational amplifiers and current mirrors realized using transistor arrays are presented and compared to the theoretical analysis. It is concluded that the static small signal open loop gain and the frequency response matches the performance of conventional voltage operational amplifiers. The input offset and bias errors and the common mode rejection are shown to be strongly dependent on the matching accuracy of the current mirrors used in the conveyors. The proposed configuration can easily be integrated into a monolithic amplifier in either CMOS or bipolar technology.     

Current‐mode quadrature oscillator using current differencing transconductance amplifiers

This article presents a new electronically tunable single‐element‐controlled current‐mode quadrature sinusoidal oscillator circuit using current differencing transconductance amplifiers (CDTAs). The proposed oscillator is consisted of two CDTAs, two grounded capacitors and one grounded resistor, which is beneficial to monolithic integrated circuit implementation both in CMOS and bipolar technologies. The condition of oscillation and the frequency of oscillation are independently controllable. The frequency of oscillation can also be electronically controlled by adjusting the bias current of CDTA. The circuit provides four quadrature current outputs and two quadrature voltage outputs. The current output terminals possess high impedance level. PSPICE simulation results are used to verify the performance of the proposed circuit implemented at the transistor level. The measurement results support the computer simulations.     

Floating active inductor based Class-C VCO with 8 digitally tuned sub-bands

A fully integrated floating active inductor based voltage-controlled oscillator (VCO) is presented. The active inductor employs voltage differencing transconductance amplifier (VDTA) as a building block. The designed VCO achieves frequency tuning by varying the bias current through the VDTA and utilizes a Class-C topology for improving the phase noise performance. The inductor-less VCO is designed and implemented in a 45-nm CMOS process and its performance is estimated using Virtuoso ADE of Cadence. Operating at a supply voltage of ±1 V, the proposed VCO consumes 0.44–1.1 mW corresponding to the oscillation frequency of 1.1–1.8 GHz thereby exhibiting a tuning range of 48.27%. The phase noise of the VCO lies in the range of −94.12 to −98.37 dBc/Hz at 1 MHz offset resulting in a FOM of −172.14 to −176.69 dBc/Hz.     

20-GHz Quadrature Injection-Locked LC Dividers With Enhanced Locking Range

Quadrature injection-lockedLC dividers with either a Miller topology or an injection-lockedLC VCO topology are coupled with transconductors to enhance their locking range. The effect of the transconductance coupling is analyzed theoretically and through circuit simulation. Both topologies were fabricated by 90-nm CMOS technology with a target input center frequency of 20 GHz and output frequency of 10 GHz. The measured locking range for the Miller topology with transconductance coupling is 25.3%, compared to 20.9% without coupling. The measured locking range for the injection-locked LC VCO topology with transconductance coupling is 18.1%, compared to 12.9% without coupling. Moreover, power consumption for both dividers is 6.4 mW with a 1.2-V supply.     

Resistorless dual-mode quadrature sinusoidal oscillator using a single active building block

This paper presents a new realization of resistorless mixed-mode (i.e. both voltage-mode and current-mode) quadrature sinusoidal oscillator using a new active building block (ABB) called the differential voltage current-controlled conveyor transconductance amplifier (DVCCCTA). The proposed oscillator circuit uses a single DVCCCTA, two grounded capacitors (GCs) and does not employ any external linear resistors. The tuning laws for the condition of oscillation (CO) and the frequency of oscillation (FO) are non-interactive; and controlled by separate bias currents. The circuit provides two explicit quadrature current outputs and two quadrature voltage outputs and thus can be classified as a mixed-mode quadrature oscillator. Another notable feature of the proposed circuit is that it can also be used as a biquadratic filter to realize low-pass and band-pass filtering functions simultaneously. Non-ideal analysis of the circuit is provided and PSpice simulation results have been included to verify the workability of the proposed circuit.     

Super Class-AB OTAs With Adaptive Biasing and Dynamic Output Current Scaling

A new family of single-stage super Class-AB operational transconductance amplifiers (OTAs) suitable for low-voltage operation and low power consumption is presented. Three novel topologies are proposed featuring simplicity and compactness. They are based on the combination of adaptive biasing techniques for the differential input stage and nonlinear current mirrors for the active load that provide additional dynamic current boosting. The OTAs have been fabricated in a standard 0.5-mum CMOS process. Experimental results show a greatly improved slew rate by factors 30-60 and gain-bandwidth product by factors 11.5-17 when compared to a classical Class-A OTA. The circuits are operated at plusmn1-V supply voltage with only 10 muA of bias current     

Simple sinusoidal oscillator using opamp compensation poles

The Letter introduces a new, extremely simple, sinusoidal oscillator based on opamp compensation poles. The circuit employs only four components, two internally compensated opamps, one resistor and a grounded capacitor, and can generate sinusoidal oscillations of frequencies up to the gain bandwidth product of the opamps. with modification(s), using an additional opamp or two analogue multipliers, the circuit can be readily converted into a VCO. Experimental results and SPICE simulations have confirmed the workability of the various modes of operation of the proposed configuration.<>     

A compact and low-phase-noise Ka-band pHEMT-based VCO

A low phase-noise Ka-band monolithic voltage-controlled oscillator (VCO) designed using the negative resistance concept is reported. A circuit fabricated using the three-dimensional monolithic microwave integrated circuit technology exhibits a high integration level; its size is a record at just 0.5 mm/sup 2/. On-wafer measurements demonstrate a low phase noise of -102 dBc/Hz at a 1-MHz offset. The VCO delivers an output power of 11.8 dBm at the center frequency of 28.3 GHz. The frequency tuning range is more than 3.8 GHz. Dependence of the circuit performance on the bias conditions is also reported and suggests that an optimum phase-noise characteristic can be achieved when biasing the transistor to optimize its transconductance and noise figure.     

一种跨导线性化低相噪压控振荡器

介绍了一种跨导线性化的宽带压控振荡器,由谐振腔电路、偏置电路、可编程电容阵列组成。提出一种通过电容隔直将有源器件进行交叉耦合的谐振腔结构,实现了有源器件的跨导线性化,大幅减小了有源器件自身的固有噪声,改善了压控振荡器的相位噪声特性。通过可编程电容阵列电路,可在压控振荡器内进行频率调节,扩展了振荡频率范围。测试结果表明,压控振荡器的振荡频率覆盖5 400~7 300 MHz,频率覆盖比达26%,在7 300 MHz时,相位噪声达到-128 dBc/Hz@1 MHz。该压控振荡器可作为高性能频率合成器的核心器件,构成本振信号源,可被广泛应用于无线基站、频谱监测等多种领域。     

Low Phase-Noise and Low-Power CMOS VCO Constructed in Current-Reused Configuration

A Ku-band CMOS voltage-controlled oscillator (VCO) constructed in a modified current-reused configuration is presented in this letter. Two dc level shifters combined into two metal-insulator-metal capacitors are adopted to solve the transconductance and load mismatch problems of the conventional current-reused VCO for obtaining more symmetrical oscillation signals and lowering the phase noise of oscillator. A prototype was designed and measured to verify the design concept. The measurement results demonstrate the central oscillation signal of 16 GHz to be associated with the 900 MHz tuning range and -111 dBc/Hz phase noise at 1 MHz offset. The power consumption of the VCO core is only 8.1 mW. The measurement result evaluated by means of a figure of merit is about -186.8 dBc/Hz.     

Voltage-mode quadrature sinusoidal oscillator with current tunable properties

This letter presents a realization of voltage-mode quadrature sinusoidal oscillator with independent current tunable frequency of oscillation. The circuit uses a single differential voltage current conveyor transconductance amplifier (DVCCTA) as the active building block and four all grounded passive elements. PSPICE simulation results have been included to verify the theoretical results.     

Current-Mode Multiphase Sinusoidal Oscillator Using Current Differencing Transconductance Amplifiers

This paper describes a simple current-controlled current-mode multiphase sinusoidal oscillator based on current differencing transconductance amplifiers (CDTAs) as active components. The proposed oscillator circuit, which employs only one CDTA and one grounded capacitor for each phase, can generate arbitrary n current-output signals (n being even or odd) equally spaced in phase, all at high output impedance terminals. The oscillation condition and the oscillation frequency can be controlled electronically and independently through the bias current of the CDTA. The oscillator has low-component count, low-sensitivity performance, and is highly suitable for monolithic implementation. PSPICE simulation results are given to confirm the operation of the proposed oscillator.     

Impedance projection based transconductance amplifier

A current feedback technique is proposed to realise the transposition of grounded impedance to a floating impedance or transconductance. This technique, that can be viewed as an impedance projection, also allows one to implement a new current conveyor topology and to extend applications based on transconductance amplification. A theoretical approach of this new technique using a grounded impedance, two classical transconductance amplifiers and one second generation current conveyor only is presented.