Current-mode Squarer Research Articles

Novel CMOS MO‐CFDITA based fully electronically controlled square/triangular wave generator with adjustable duty cycle

This study presents a novel square/triangular wave generator based on multiple-output current follower differential input transconductance amplifier (MO-CFDITA) with reduced complexity in terms of transistors. The proposed generator comprises of single MO-CFDITA and one grounded capacitor only which makes the proposed generator circuit suitable to integrated circuit implementation. The proposed generator provides output square wave in current mode and output triangular wave in voltage mode. The amplitude of current-mode square wave is electronically and independently tunable via bias current. The DC level of the triangular wave is also electronically adjustable. The proposed generator has dual-slope operation and its duty cycle is adjustable with the help of DC current source over a range of 5–95%. The proposed generator consumes a power of 1.45 mW only and it is usable up to 50 MHz which is quite good operating frequency range. To examine the performance of the proposed generator, the cadence VIRTUOSO simulation results have been depicted. Additionally, the simulation results and performance parameters of complementary metal–oxide–semiconductor (CMOS) MO-CFDITA are included. The practicality of the proposed generator is verified through the experimental results.

Current-mode square wave generators based on a single CDTA

ABSTRACTThis paper proposes two designs for current-mode square wave generators based on a current-differencing transconductance amplifier (CDTA). Both the proposed circuits are compact and employ a single CDTA with only two external passive components. The first circuit has a fixed duty-cycle topology and can generate a symmetrical square wave with variable frequency. The second circuit has a variable duty-cycle design and can operate in a current-controlled dual duty-cycle mode with a single-circuit topology. The proposed generators allow independent control of the operating frequency, output amplitude, and duty cycle by tuning diverse circuit parameters. This paper discusses several previous designs for square wave generators and presents the circuit principles, related governing formulas, and nonideal problems for the proposed circuits. In addition, computer simulations and experimental results, which are consistent with those of the theoretical analyses and confirm the feasibility of the new generators, are presented.

Single Active Element-Based Tunable Square/Triangular Wave Generator with Grounded Passive Components

This paper presents a novel circuit of tunable square/triangular wave generator based on single active element and grounded passive components. The structure of the proposed generator is simple as it consists of one multiple-output differential voltage current conveyor transconductance amplifier (MO-DVCCTA) as active element and one grounded resistor and one grounded capacitor as passive components. The proposed generator provides triangular wave in voltage mode and square wave in both voltage mode and current mode simultaneously. The proposed generator enjoys the features of availability of square wave in both current mode and voltage mode, electronically tunable duty cycle via DC current over a 93–7% range, electronically and independently adjustable DC level of voltage-mode square wave and triangular wave via an additional DC current, independent and electronic control of amplitude of current-mode square wave by bias current and independent tunability of oscillation frequency by grounded capacitor. Moreover, the operation of the proposed generator at 50% duty cycle exhibits the electronic and independent control of oscillation frequency via bias current also. As an additional feature, the proposed generator exhibits <1% nonlinearity up to a frequency of 123.9 kHz. The maximum temperature coefficient of oscillation frequency over a temperature range of 0–50 \({^{\circ }}\)C is found 185 ppm/\({^{\circ }}\)C which is quite good in view of temperature stability of the oscillation frequency. The prototype of MO-DVCCTA based on commercial ICs has been used in the realization of circuit of the proposed generator. The PSPICE simulation results and experimental results are given to validate the proposed generator.

Design of Z-copy controlled-gain voltage differencing current conveyor based adjustable functional generator

This paper introduces interesting active element and its application in the field of square and triangular wave generators. Active element, so-called Z-Copy Controlled Gain Voltage Differencing Current Conveyor (ZC-CG-VDCC), has availability of three mutually independently and electronically adjustable parameters (transconductance, intrinsic resistance of the current input terminal and current gain between two terminals) that are very popular for control of applications today. In addition, a proposed device utilizes very useful z-copy (additional auxiliary terminal) features and two terminals providing voltage difference. All mentioned features are beneficial in mixed-mode circuit synthesis and design of adjustable applications (active filters, oscillators, generators, modulators, etc.). Electronically adjustable properties of the device are involved in the design of an adjustable generator. The generator provides voltage- and current-mode square wave outputs that can be also used for differential square wave output when very simply modified. Application of the generator in simple pulse width modulator (PWM) is also introduced. A detailed analysis and Spice simulation results are given and main features of the circuits are compared to electronically controllable solutions of recent development in this field.

Fully Programmable Gaussian Function Generator Using Floating Gate MOS Transistor

Floating gate MOS (FGMOS) based fully programmable Gaussian function generator is presented. The circuit combines the tunable property of FGMOS transistor, exponential characteristics of MOS transistor in weak inversion, and its square law characteristic in strong inversion region to implement the function. Two-quadrant current mode squarer is the core subcircuit of Gaussian function generator that helps to implement full Gaussian function for positive as well as negative input current. FGMOS implementation of the circuit reduces the current mismatching error and increases the tunability of the circuit. The performance of circuit is verified at 1.8 V in TSMC 0.18 μm CMOS, BSIM3, and Level 49 technology by using Cadence Spectre simulator.