Quadrature oscillator and universal filter based on translinear current conveyors

This paper presents quadrature oscillator and universal filter based on translinear current conveyors. The proposed circuit can realize as a quadrature oscillator or a universal filter without changing the circuit topology. When it works as a quadrature oscillator, four quadrature current outputs and two quadrature voltage outputs can be obtained. The condition and frequency of oscillation of oscillator can be controlled orthogonally and electronically. When it works as a universal filter, low-pass, band-pass, high-stop, band-stop, and all-pass filtering functions can be obtained simultaneously. The natural frequency and quality factor of filters can be controlled orthogonally and electronically. The proposed topology is simulated using PSPICE simulators and experimental results are also used to confirm workability of new circuit.     

New high accuracy CMOS current conveyors

In this paper, a new CMOS CCII⁺ is proposed. The circuit is characterized by high precision in voltage tracking and exhibits very low input resistance. An adaptive voltage offset cancellation methodology is introduced and then applied to the proposed circuit. As a result, a higher accuracy CCII⁺ is presented. For both circuits, the voltage offset cancellation is independent of the input current and voltage. To demonstrate the strength of the proposed architectures, fair comparisons with Liu and Yodprasit CCII realizations are held.     

Current controlled oscillator based on translinear conveyors

A current controlled oscillator based on translinear current conveyors is presented. The oscillation frequency can be varied proportionally to the bias current. The oscillator uses two CCCII's, and two grounded capacitors. SPICE simulation results agree with the theory     

Sinusoidal frequency doubler and full-wave rectifier based on translinear current-controlled current conveyors

A circuit design technique that employs translinear current-controlled current conveyors as active circuit elements to design a sinusoidal frequency doubling and full-wave rectifying circuit is proposed. The circuit can realize the sinusoidal frequency doubler and full-wave rectifier without changing the circuit configuration. The proposed frequency doubling and rectifying action is exploited from the translinear characteristic of the current conveyor. Simulation and experimental results are given to confirm the theoretical predictions.     

New electronically tunable current-mode universal biquad filter using translinear current conveyors

In this study, a new electronically tunable current-mode universal filter with two inputs and two outputs employing one translinear current conveyor, one translinear current conveyor with controlled current gain and two grounded capacitors is presented. The proposed circuit offers the following attractive features: realisation of low-pass, band-pass, high-pass, band-stop and all-pass current responses from the same configuration; employment of the minimum active and passive components; no requirement of component matching conditions; independent current-control of the parameters natural frequency (ω_o) and quality factor (Q); low active and passive sensitivities; and high impedance output. The characteristics of the proposed circuit are simulated using PSPICE to confirm the theory.     

Current controlled bandpass filter based on translinear conveyors

A new concept to take advantage of the parasitic resistance that appears on port X of the second-generation current conveyors is introduced. This parasitic resistance, which is controllable in current, leads to the definition of the second generation current controlled conveyors (CCCII). A current controlled bandpass filter, operating in the current mode, is also described. It uses only two CCCII's and two capacitors. Its central frequency can be adjusted by acting on the bias current of the conveyors. SPICE simulation results, in agreement with theory, are given for central frequencies around 30 MHz     

Electronically tunable multiphase sinusoidal oscillator using translinear current conveyors

A new electronically tunable current-mode multiphase sinusoidal oscillator based on translinear current conveyors is presented. The proposed oscillator circuit, which employs only one translinear current conveyor and one grounded capacitor for each phase, can generate arbitrary N output current equal-amplitude signals that are equally spaced in phase (N being even or odd), all at high output impedance terminals. The frequency of oscillation and the condition of oscillation can be controlled electronically and independently through the bias current of the translinear current conveyor. The proposed structure also has simple circuitry, low-component count, and is highly suitable for integrated circuit implementation. The theoretical results were verified by PSPICE simulation. In addition, the modification of the N sinusoidal oscillators to construct a programmable multiphase oscillator is also discussed.     

A new electronically tunable phase shifter employing current-controlled current conveyors

A new canonical current-mode (CM) filter topology is presented. It realizes first-order allpass filtering functions using two dual-output current-controlled current conveyors (DO-CCCII) and a single capacitor. The topology gives both inverting and non-inverting types of these filters. Owing to electronically tunability properties of the CCCII, phase response of the circuit can be controlled by an external control current. Realization of the allpass filter imposes no matching condition. All outputs of the filters exhibit high output impedances so that this property makes the circuits very attractive from the viewpoint of cascading in current mode. The theoretical results are verified with PSPICE simulations using a BJT realization of CCCII.     

一种基于跨导线性环CMOS CCCII的设计

设计了一种由跨导线性环电路、基本电流镜和自偏置高摆幅共源共栅电流镜构成的CCCⅡ(第二代电流控制传输器)的CMOS实现电路。文中详细分析了该电路的工作原理,并给出了Hspice仿真结果。该电路具有电源电压低、频带宽、电流传输精度高、及成本低廉且实用性好的特点。     

Signal limitations of the current-mode filters employing current conveyors

It is well known that second-generation current conveyors (CCII) are widely used for the realization of second-order current-mode universal filters. A filter with high-quality factor (Q) and gain constant (K) suffers from various signal swing restrictions especially at its angular resonance frequency (ω₀). This is due to the terminal voltages of the CCIIs limited by the power supply voltages and maximum allowable terminal currents of the CCIIs. In this paper, signal limitations of the CCII-based current-mode filters are investigated in detail. A filter example is given to exhibit the signal limitations of a universal current-mode filter. The time-domain and frequency-domain results of the proposed filter are also given to verify the theoretical analysis.     

Current-tunable current-mode multifunction filter based on dual-output current-controlled conveyors

In this paper, a current-tunable current-mode multifunction filter with two inputs and two outputs employing only four dual-output current-controlled conveyors (DO-CCCIIs) and two grounded capacitors is proposed. By appropriately connecting the input and output terminals, the proposed circuit can provide lowpass, bandpass, highpass, bandstop and allpass current responses. The filter also offers an independent electronic control of the natural frequency (ω_o) and the quality factor (Q) through adjusting the bias currents of the DO-CCCIIs. No critical matching conditions are imposed for realizing all the filter responses, and all the incremental parameter sensitivities are low. The characteristics of the proposed circuit are simulated using PSPICE to confirm the theory.     

基于CCCII的系列电路

本文提出了一系列基于CCCII（电流控制第二代电流传输器）的电路：接地与浮地回转器、频变负阻器及电容乘法器，这些电路的参数均可通过各CCCII的外接电流进行调节。所提出的系列电路在电路与系统的设计中有着重要的应用价值。     

On the frequency limitations of the circuits based on second generation current conveyors

An equivalent circuit for the translinear implementation of the second generation current conveyors with positive or negative current transfer is given. This circuit takes into account the various parasitic elements of the conveyor which induce frequency limitations (gain values, poles of the transfers, and parasitic impedances). The methods allowing the determination of the values for these parasitic elements are indicated and discussed. The effect of each element on the frequency responses of the circuits using the conveyors are studied in every detail. The frequency behavior of two circuits are analyzed as examples: a voltage amplifier without feedback and two configurations for a second order biquad filter operating in current-mode. All the theoretical results of the analysis are well confirmed from SPICE simulations.     

Insensitive high-output impedance minimum configuration SITO-type current-mode biquad using dual-output current conveyors and grounded passive components

This paper presents a high-output impedance current mode single-input and three-outputs (SITO)-type multifunction filter which employs three dual-output current conveyors to simultaneously realize low-pass, high-pass and band-pass responses. The proposed circuit uses grounded-virtually grounded passive components (which makes the circuit ideal for integration and tuning). Moreover, it has low active and passive component sensitivities and does not require critical matching conditions and cancellation constraints.     

Current conveyor based R- and C- multiplier circuits

One of the most limiting problems in the design of integrated circuits is related with the realization of resistance and capacitance values higher than those normally integrable. To meet the objectives of realizing resistance and capacitance values higher than those normally integrable three R- and C- multiplier circuits using IC AD844 configured as a second-generation current conveyor (CCII+) with a built-in buffer stage are described, analyzed and studied experimentally. The effects of AD844 non-idealities are also evaluated and discussed. The approach provides the designer with a new building block suitable for integrated and tunable filters. Computer simulations under PSpice environment are also reported.     

Floating inductance simulation based on current conveyors

A basic floating inductance simulation circuit with grounded capacitance using only noninverting second-generation current conveyors as active elements is introduced. The circuit is modified by using current controlled conveyors, yielding electronically tunable inductances. Simulation results are also presented     

Low-voltage subthreshold CMOS current mode circuits: Design and applications

The world has migrated to portable applications ranging from smart phones to Lab on a Chip applications. However they come with a new set of challenges for analog IC designers. Low voltage operation, small area and low noise are the critical design criteria for portable devices. This paper presents a g_m/I_D based design methodology for low voltage current mode circuits using standard CMOS technology. A second generation current conveyor (CCII) and a current feedback operational amplifier (CFA) are designed using the discussed design procedure. Both circuits operate from a single 0.4 V supply. The CCII is used to implement an instrumentation amplifier. Multiple applications are implemented using the CFA. Post layout simulation using TSMC 90 nm and UMC 130 nm technology show that the presented design procedure is an attractive solution for low voltage CMOS current mode circuits.     

CMOS sinusoidal oscillator based on current-controlled current conveyors

A new realisation of a CMOS single resistance current-controlled current mode oscillator using active grounded resistances is described. A prototype has been realised in 0.8 /spl mu/m CMOS technology from AMS. Measurement results confirm oscillation over 10 MHz, low output distortion and wide tuning range.     

Current-mode electronically tunable biquadratic filters consisting of only CCCIIs and grounded capacitors

In this paper, a current-mode (CM) analog filter for simultaneously realizing high output impedance low-pass, band-pass and high-pass analog responses besides high output impedance notch and all-pass analog filter responses with interconnection of the relevant output currents, is presented. Also, two CM filters for simultaneously providing high output impedance universal filter responses are derived from the proposed one. All of the introduced CM topologies employ a canonical number of only grounded capacitors without requiring any resistors, and do not need critical component matching conditions. All of the developed circuits have low input impedance and high output impedance resulting in easy cascadability with other CM ones. Frequency dependent non-ideal gain and parasitic impedance effects on the performance of the presented first filter are investigated as examples. In order the show the performance of the filter and verify the theory, simulations are accomplished with SPICE program.     

A 1.2 V current-mode true RMS-DC converter based on the floating gate MOS translinear principle

A current-mode true RMS-DC converter based on a novel synthesis of translinear loop squarer/divider and simplified current-mode low-pass filter is presented. The circuit employs floating gate MOSFETs that operate in strong inverted saturation region for electronically simulated translinear loop. The converter features very low supply voltage (1.2 V), two-quadrant input current, immunity from body effect, low circuit complexity, and wide input dynamic range. Simulation results by HSPICE show high performance of the circuit and confirm the validity of the proposed design technique.