Current-mode Quadrature Oscillator Research Articles

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 .

Current-Controlled Current-Mode Quadrature Oscillator Using Translinear Current Conveyors

In this paper, a current-mode quadrature oscillator using second-generation current conveyors (CCIIs) is presented. The proposed oscillator consists of two CCIIs, two grounded capacitors and two grounded resistors. The circuit is suitable for integrated circuit implementation by using grounded capacitors. In addition, a new current-controlled current-mode quadrature oscillator using two current controlled second generation current conveyors (CCCIIs) and two grounded capacitors can be obtained by replacing CCIIs and resistors series at X terminals with CCCIIs. The condition of oscillation and frequency of oscillation can be orthogonally controlled. The frequency of oscillation can be controlled by grounded resistors and external bias currents. The proposed circuits have been simulated by SPICE simulations. The simulation results are confirmed the proposed theory.

Current-mode universal filter and quadrature oscillator using current controlled current follower transconductance amplifiers

This paper presents a new current-mode quadrature oscillator and universal filter that employs two current controlled current follower transconductance amplifiers and two grounded capacitors. The proposed circuit can be realized either as a quadrature oscillator or as a universal filter without changing circuit topology. In case the circuit works as a quadrature oscillator, the condition and the frequency of oscillation can be independently and electronically controlled. Four-phase quadrature current outputs and two-phase quadrature voltage outputs can also be obtained. In case the circuit works as a universal filter, low-pass, high-pass, band-pass, band-stop and all-pass filtering functions can be obtained simultaneously by appropriately selecting the input and output signals. The natural frequency and the quality factor of filter can also be obtained independently and electronically. PSPICE simulation results are used to verify the workability of the new topology.

RC oscillators based on high‐Qfrequency‐selecting network

In this study, a traditional voltage-mode oscillator consisting of a high-Q band-pass filter and a voltage amplifier is transformed into a current-mode oscillator employing a trans-conductance amplifier. Furthermore, a current-mode quadrature oscillator with a high-Q band-pass filter and second generation current-controlled conveyors (CCCIIs) is presented. Since the loop of the oscillator has rich selectivity, the oscillator produces less distortion. Also, the 3 dB bandwidth, oscillation criterion, and oscillation frequency of the oscillator could independently, linearly, and electronically be tuned by the aid of adjusting bias currents of the CCCIIs. Finally, the validity of the designed circuit is verified by means of the computer simulation and the non-ideal analysis is performed to explain the results of the simulation. The results show that the designed circuit is workable.

A wideband linear tunable CDTA and its application in field programmable analogue array

In this paper, a NMOS-based wideband low power and linear tunable transconductance current differencing transconductance amplifier (CDTA) is presented. Based on the NMOS CDTA, a novel simple and easily reconfigurable configurable analogue block (CAB) is designed. Moreover, using the novel CAB, a simple and versatile butterfly-shaped FPAA structure is introduced. The FPAA consists of six identical CABs, and it could realize six order current-mode low pass filter, second order current-mode universal filter, current-mode quadrature oscillator, current-mode multi-phase oscillator and current-mode multiplier for analog signal processing. The Cadence IC Design Tools 5.1.41 post-layout simulation and measurement results are included to confirm the theory.

Second Order Current-mode Quadrature Oscillators Using OTAs

This article presents new current-mode quadrature oscillator circuits using OTA which are designed from block diagram. The proposed circuits consist of three OTAs and two grounded capacitors. The circuits have high output impedance appropriate for cascade connection application in current mode technique which is capable to directly drive load. The oscillators use only grounded capacitor which is very appropriate for further development into an integrated circuit. In addition, the condition of oscillation can be adjusted orthogonally from the frequency of oscillation. The results of PSPICE simulation program are corresponding to the theoretical analysis.

CCCCTA-based resistorless voltage and current mode quadrature oscillator

CCCCTA-based resistorless voltage and current mode quadrature oscillator

DUAL-OUTPUT CURRENT DIFFERENCING TRANSCONDUCTANCE AMPLIFIERS-BASED CURRENT-MODE SINUSOIDAL QUADRATURE OSCILLATORS

This paper presents three current-mode quadrature oscillator (QO) circuits based on dual-output current differencing transconductance amplifier (DO-CDTA) which is designed from block diagram. The proposed circuits consist of two DO-CDTAs and two grounded capacitors. The circuits can provide two sinusoidal output currents with 90° phase difference. The condition of oscillation (CO) can be adjusted independently from the frequency of oscillation (FO) by adjusting the bias currents of the DO-CDTA. The proposed circuits have high output impedance appropriate for cascade connection application in current mode which is capable to directly drive load. The circuits use only grounded capacitors without any external resistor which is very appropriate for further development into an integrated circuit. Moreover, the oscillator circuits can also adjust amplitude of the output signal. The results of PSPICE simulation program are corresponding to the theoretical analysis.

Current-mode universal filter and quadrature oscillator using CDTAs

A current dierencing transconductance amplier (CDTA)-based multiple-input single-output (MISO) current- mode universal lter and a quadrature oscillator (QO) are presented in this paper. The same circuit is used in the lter and oscillator, which only consists of 2 CDTAs and 2 capacitors. The universal lter can realize low-pass, high-pass, band-pass, band-stop, and all-pass biquad lter functions. With a slight modication of the lter, a new current-mode QO can be obtained easily. The natural frequency and quality factor of the lter and the conditions of oscillation and frequency of oscillation of the QO are all orthogonally adjustable through the bias currents of the CDTAs. Moreover, the passive and active sensitivities of the MISO lter and QO are low. PSpice simulation and experimental results are

CDTA-based electronically tunable current-mode quadrature oscillator

This paper presents two new current differencing transconductance amplifiers (CDTAs)-based electronically tunable current-mode four-phase quadrature oscillators (QO). The proposed QOs consist of two CDTAs, one resistor and two grounded capacitors, respectively, which are suitable for monolithic integration. The condition of oscillation (CO) and frequency of oscillation (FO) can be independently controlled, and the FO can be electronically tunable by adjusting the bias current of the CDTA. Moreover, the QOs can provide four quadrature output currents at high-output-impedance nodes, which enable the QOs can be connected directly to the next stage without any impedance matching requirements. Cadence IC Design Tools 5.1.41 (Cadence Design Systems Inc., San Jose, CA) post-layout simulation results and experimental evidence are included to confirm the theory.

First CFOA-based explicit-current-output quadrature sinusoidal oscillators using grounded capacitors

To date, no current-feedback operational amplifier (CFOA)-based sinusoidal oscillator has been reported which provides all the following features simultaneously: (i) current-mode quadrature sinusoidal oscillator providing two explicit-current-outputs (ECOs) from high output impedance terminals, (ii) employing no more than three CFOA ICs and six passive components, which include two grounded capacitors, (iii) offers independent tuning of the condition of oscillation (CO) via a resistor and (iv) provides tunability of the ratio of amplitudes of the generated quadrature ECOs via a separate resistor. To the best of authors' knowledge, this article reports first CFOA-based QOs in current-mode (i.e. providing two ECO signals). Experimental results using AD844 CFOA ICs from Analog Devices have been included to verify the workability of the proposed oscillator circuits. An example automatic gain control (AGC) loop to regulate the oscillation amplitude and control the THD has also been used and verified using SPICE simulations using the AD844 macro-model.

Current-mode quadrature oscillator based on CCCDTAs with noninteractive dual-current control for both condition of oscillation and frequency of oscillation

The realization of 2 current-mode quadrature oscillators using current-controlled current differencing transconductance amplifiers (CCCDTAs) and grounded capacitors is presented. The proposed oscillators can provide 2 sinusoidal output currents with a 90° phase difference. They enable noninteractive dual-current control for both the condition of oscillation and the frequency ofi oscillation. The high-output impedances of the configurations enable the circuit to be cascaded without additional current buffers. The use of only grounded capacitors is ideal for integration. The circuit performances are depicted through PSpice simulations; they show good agreement to theoretical anticipation.

CCTAs based Current-mode Quadrature Oscillator with High Output Impedances

This article presents a current-mode quadrature oscillator. The proposed oscillator can provide 2 sinusoidal output currents with 90 0 phase difference. It also provides high output impedances that make the circuit able to directly drive load without additional current buffer. The condition of oscillation and frequency of oscillation can be controlled independently and electronically by adjusting the bias currents of the CCTAs. The circuit uses 3 current controlled transconductance amplifiers (CCTAs) and 2 grounded capacitors. The proposed circuit uses only grounded capacitors without additional external resistors, the proposed circuit is considerably appropriate to further developing into an integrated circuit. The results of PSPICE simulation program are corresponding to the theoretical analysis. 

Electronically Controllable Fully-Uncoupled Explicit Current-Mode Quadrature Oscillator Using VDTAs and Grounded Capacitors

An electronically controllable fully uncoupled explicit current-mode quadrature oscillator employing Voltage Differencing Transconductance Amplifiers (VDTAs) as active elements has been presented. The proposed configuration employs two VDTAs along with grounded capacitors and offers the following advantageous features 1) fully and electronically independent control of condition of oscillation (CO) and frequency of oscillation (FO); 2) explicit current-mode quadrature oscillations; and 3) low active and passive sensitivities. The workability of proposed configuration has been demonstrated by PSPICE simulations with TSMC CMOS 0.18 μm process parameters.

All Current Mode RF Receiver Front End

In this paper, an all current mode RF receiver of direct conversion for 802.11b WLAN has been proposed. The front end of this receiver, containing a current mode LNA plus mixer (CLPM) circuit and a current mode quadrature ring oscillator (CQRO), has been designed and simulated in chartered 0.18 μm CMOS process. The proposed method features that the pseudo-cascode current mirrors of the current mode LNA have not been implemented in cascade, so we can decrease the supply voltage and increase the output impedance by adding a common-gate transistor. The current mode mixer has been composed by the four added common-gate transistors; this implementation makes the current mode mixer a two-layer structure that reduces the supply voltage. The current mode quadrature oscillator is a four current mode stage ring oscillator employing feed forward paths. The CLPM has a measured power conversion gain of 18.6 dB, an input referred third-order intercept point (IIP3) of −0.53 dBm. The total noise figure is 3.9 dB and the power is only 15 mW by post-simulations. The CQRO core current consumption is 24 mA with a 1 V supply. The phase noise results in −121.61, −148 dBc/Hz at 1 MHz, and 10 MHz from the carrier, respectively.

Single CDTA-based current-mode quadrature oscillator

This letter presents a single CDTA (Current Differencing Transconductance Amplifier)-based current-mode quadrature oscillator (QO). The proposed circuit structure is very simple, which only consists of one CDTA, one resistor and two capacitors, and it is easy for monolithic integration. The oscillation frequency of the QO can be electronically controlled by the bias current of the CDTA. Moreover, the oscillator can provide two quadrature current outputs. PSPICE simulation results are provided to verify all the theoretical analysis.

Novel Ultra-Low-Power Class AB CCII+ Based on Floating-Gate Folded Cascode OTA

In this paper, a novel low-voltage ultra-low-power class AB current conveyor of the second generation based on folded cascode operational transconductance amplifier OTA with floating-gate differential pairs is presented. The main features of the proposed conveyor are design simplicity and rail-to-rail input voltage range at a low supply voltage of ±0.5 V. The proposed conveyor has a reduced power consumption of only 10 μW. Due to these features, the proposed conveyor could be successfully employed in a wide range of low-voltage low-power analog signal processing applications. PSpice simulation results using the 0.18 μm CMOS technology from TSMC are included to prove the results. As an example of application, a current-mode quadrature oscillator is designed and its functionality is proved by simulation.

Current-mode variable frequency quadrature sinusoidal oscillators using two CCs and four passive components including grounded capacitors

This paper reports realizations of current-mode quadrature sinusoidal oscillator using only two multiple-output current conveyors (first or second generation current conveyor CCI/CCII) and four passive components including two grounded capacitors. Therefore, the circuits employ minimum number of passive components to realize a second-order sinusoidal oscillator. Three types of circuits are reported depending on the condition of oscillation and frequency of oscillation (FO). The circuits have FO controllable by either resistor or capacitor and are suitable to be used as variable frequency oscillator for different applications. All the circuits provide two explicit quadrature current outputs from high output impedance terminals. PSPICE simulation results are included to verify the workability of the proposed circuits.

Resistorless realization of current-mode first-order allpass filter using current differencing transconductance amplifiers

This paper presents a realization of a current-mode first-order allpass filter using two current differencing transconductance amplifiers (CDTAs) as the active components and one virtually grounded capacitor as the only passive component. The proposed filer requires no external resistor and is electronically adjustable by varying the external bias current of the CDTA. No component-matching constraints are required. The circuit realizes both inverting and non-inverting types of allpass filters, and also exhibits high-output impedances, which are easy cascading in the current-mode operation. As an application of the proposed CDTA-based allpass section, a current-mode quadrature oscillator is realized. PSPICE simulation results are given to confirm the theoretical analysis.

Novel voltage/current-mode quadrature oscillator using current differencing transconductance amplifier

This letter proposes a new realization of voltage/ current-mode (CM) quadrature oscillator (QO) using Current Differencing Transconductance Amplifier (CDTA) as the active element. The proposed circuit employs canonic number of components, namely two CDTAs, one resistor and two grounded capacitors. The oscillator is capable of providing two explicit quadrature current outputs and two quadrature voltage outputs. Moreover, the circuit enjoys the advantage of independent control of condition of oscillation (CO) and frequency of oscillation (FO). The non-ideal analysis and sensitivity study of the circuit has been carried out and the circuit exhibits a good sensitivity performance. B2SPICE simulation results are included that validate the working of the circuit.