Novel allpass filter configuration employing single OTRA

A new circuit configuration uses a single operational transresistance amplifier (OTRA) and four passive elements to realize both first- and second-order allpass filters. Owing to internal grounding of the OTRA input terminals, effects of input parasitics are significantly reduced. Applications of the circuit include the realization of the phase equalizer, the quadrature oscillator, and the high-Q bandpass filter for analog signal processing. The performance of the allpass filter is illustrated by circuit-level simulation of a quadrature oscillator with CMOS realization of the OTRA.     

Four new oscillators using operational transresistance amplifier

In this paper, four new sinusoidal waveform generators based on the operational transresistance amplifier (OTRA) are presented. The first proposed circuit is a minimum component RC sinusoidal oscillator circuit with one OTRA and a few passive components. The second and third proposed circuits consist of one OTRA and a few passive components, among them two passive components are connected to ground. These circuits are able to control the condition of oscillation and frequency of oscillation independently. The fourth proposed quadrature oscillator circuit uses two OTRAs as main active building blocks and a few external passive components to generate the oscillations. The IC AD844AN is adopted to implement the proposed circuits on a laboratory breadboard with external passive components. Both the SPICE simulation and experimental results are given to verify the theoretical analysis of the proposed circuits.     

Novel Transimpedance Type First-Order All-Pass Filter Using Single Otra

A novel transimpedance-mode first-order all-pass filter configuration is proposed. It uses a single operational transresistance amplifier (OTRA) and few passive components. The proposed circuit is structurally all-pass that does not impose any component matching condition. The proposed circuit is insensitive to parasitic input capacitances and input resistances due to the internally grounded input terminals of the OTRA. It provides an alternative realization of phase equalizers for analog signal processing applications by providing also current-to-voltage conversion. The theoretical results are verified with PSPICE simulations using a CMOS realization of OTRA.     

New realization of third order sinusoidal oscillator using single OTRA

In this paper, a new, single operational transresistance amplifier (OTRA) based third order sinusoidal oscillator is presented. The nonideal behavior of proposed structure has been analyzed using single and double pole models of the OTRA. It is observed that for high-frequency applications the effect of nonidealities may be eliminated through self-compensation. Active and passive sensitivities are computed for the proposed structure and are found to be less than unity rendering proposed circuit insensitive to component variations. Workability of the proposed oscillator is verified through Analog Design Environment (ADE) spectre tool provided by cadence virtuoso using 0.18 μm CMOS process parameters. Monte Carlo analysis is also carried for the proposed structure. Total harmonic distortion (THD) is found to be less than 2.6%. Post layout simulations; experimental results are also included to validate the theory.     

OTRA-based Grounded-FDNR and Grounded-Inductance Simulators and Their Applications

New grounded frequency-dependent negative-resistance (FDNR) and grounded inductance simulation circuits, employing an operational trans-resistance amplifier (OTRA) along with two capacitors, two resistors and a voltage follower have been introduced. The application of the new simulators in the realization of a single-resistance controlled oscillator (SRCO) and a single-capacitance controlled oscillator (SCCO) has been demonstrated and the effect of parasitic capacitance and input and output resistances of the OTRA on the performance of these circuits has been evaluated. The workability of the application circuits has been confirmed by experimental results using an OTRA-implemented from commercially available AD844-type current-feedback operational amplifiers (CFOAs).     

Transimpedance Type Fully Integrated Biquadratic Filters Using Operational Transresistance Amplifiers

Operational transresistance amplifier (OTRA) is an inherently suitable active building block for transimpedance type signal processing because of its current input/voltage output nature. It is due to the fact that both input and output terminals of OTRA are characterized by low impedance. In this paper, we present an OTRA based transimpedance type biquadratic filter configuration. It realizes all five different filtering functions, namely low-pass, high-pass, band-pass, notch and all-pass. The configuration can be made fully integrated based on MOS-C realization by making use of current differencing and internally grounded inputs of OTRA.     

Cascadable Current-Mode Biquad Filter and Quadrature Oscillator Using DO-CCCIIs and OTA

This article introduces a circuit which can function both as a quadrature oscillator and as a universal biquad filter (lowpass, highpass, bandpass). When the circuit functions as a universal biquad filter, the quality factor and pole frequency can be tuned orthogonally via the input bias currents. When it functions as a quadrature oscillator, the oscillation condition and oscillation frequency can be adjusted independently by the input bias currents. The proposed circuit can work as either a quadrature oscillator or a biquad filter without changing the circuit topology. The amplitude of the proposed oscillator can be independently controlled via the input bias currents. The proposed oscillator can be applied to provide amplitude modulated/amplitude shift keyed signals with the above-mentioned major advantages. The circuit is very simple, consisting of four dual-output second generation current controlled current conveyors (DO-CCCIIs), one operational transconductance amplifier (OTA), and two grounded capacitors. Without any external resistors and using only grounded elements, this circuit is therefore suitable for IC architecture. PSPICE simulation results are depicted here, and the given results agree well with the theoretical analysis. The power consumption is approximately 7.32 mW at ±2.5 V supply voltages.     

基于单个CDCTA的低压电控调谐电流模式多相位正弦振荡器的设计

提出了一种全新的电流模式多相位正弦振荡器电路。该电路仅使用一个电流差分级联跨导放大器(CDCTA)和接地无源元件,能产生n(n为奇或偶)个等相位差的电流信号,电路结构简单、工作电压低、输出阻抗高、振荡频率高,而且振荡条件和振荡频率独立可调。计算机CADENCE软件仿真和流片测试结果验证了理论分析的正确性。     

DC instability of the series connection of tunneling diodes

An oscillator with a series connection of tunneling diodes produces significantly higher power than a single diode oscillator. However, a circuit with series-connected tunneling diodes biased simultaneously in the negative differential resistance (NDR) region of the I-V curve is dc unstable. This dc instability makes the series connection oscillator fundamentally different from a single diode oscillator. Associated with the dc instability are the phenomena of minimum oscillation amplitude and frequency. Due to the minimum oscillation amplitude, it is critical to provide the impedance match between the oscillator circuit and the series connection at the desired oscillation amplitude level. An in depth, comprehensive analysis of the dc instability is given here. Based on this analysis, a numerical procedure is developed to accurately predict the minimum oscillation amplitude and frequency. Time domain simulations which give further insight into series-connection oscillator behavior are discussed. The effect of increasing the number of diodes on the oscillator performance is explored as well. Based on numerical and simulation results, oscillators with several tunnel diodes connected in series were designed and tested. Experimental results that confirm the existence of the minimum oscillation amplitude are presented for oscillators with two, three, and four tunnel diodes     

CMOS realization of single-resistance-controlled and variable frequency dual-mode sinusoidal oscillators employing a single DVCCTA with all-grounded passive components

In this paper, two new designs are proposed for sinusoidal oscillators based on a single differential voltage current conveyor transconductance amplifier (DVCCTA). Each of the proposed circuits comprises a DVCCTA combined with passive components that simultaneously provides both voltage and current outputs. The first circuit is a DVCCTA-based single-resistance-controlled oscillator (SRCO) that provides independent control of the oscillation condition and oscillation frequency by using distinct circuit parameters. The second circuit is a DVCCTA-based variable frequency oscillator (VFO) that can provide independent control of the oscillation frequency by adjusting the bias current of the DVCCTA. In this paper, the DVCCTA and relevant formulations of the proposed oscillator circuits are first introduced, followed by the non-ideal effects, sensitivity analyses, frequency stability discussions, and design considerations. After using the 0.35-μm CMOS technology of the Taiwan Semiconductor Manufacturing Company (TSMC), the HSPICE simulation results confirmed the feasibility of the proposed oscillator circuits.     

Single-resistance-controlled quadrature oscillator using current differencing buffered amplifiers

A single-resistance-controlled quadrature oscillator circuit using current differencing buffered amplifiers (CDBAs) as active components is proposed. The proposed circuit is realised through the employment of two CDBAs, three resistors and two grounded capacitors. Outputs of two sinusoidal with 90° phase difference are available. The oscillation condition and the oscillation frequency of the proposed quadrature oscillator can be controlled independently by a single resistor. In comparison with the previously reported circuits, the proposed configuration considerably reduces the number of passive elements.     

基于CDCTA的双模式等幅正交振荡器

针对正交振荡器实现复杂、振幅不相等、模式单一等问题,提出了一种基于电流差分级联跨导放大器的双模式正交振荡器。该电路仅使用一个电流差分级联跨导放大器、一个接地电阻和两个接地电容,可以同时产生等幅电压和电流正交信号。电路结构简单,灵敏度低,易于集成,振荡条件和振荡频率可相互独立地电控调谐。PSPICE仿真与硬件实验结果验证了理论分析的正确性。     

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.     

Design and analysis of a high speed double-tail comparator with isomorphic latch-preamplifier pairs and tail bootstrapping

In this paper, a new grounded positive lossless frequency dependent negative resistance (FDNR) simulator and two of its applications are presented. The proposed FDNR uses single OTRA and requires five number of passive components; two resistances and three capacitances. The workability of the proposed simulator is demonstrated through the realization of a single resistance controlled oscillator (SRCO) and a fifth order elliptic filter. A detail non-ideality analysis is also done for both FDNR and SRCO. In addition the sensitivity, non-ideality effect and frequency stability analysis of SRCO have been presented. Monte Carlo simulation of the SRCO output has been given and discussed. Moreover, the layout of OTRA, FDNR and SRCO and their post layout simulations in 180 nm are given. PSPICE simulation and experimental results are included to verify theory.     

基于orCAD／PSpice的晶体振荡电路设计仿真

通过对电容三点式振荡电路和石英晶体振荡器等效电路的计算分析,设计并改进了石英晶体振荡器电路。在OrCAD／PSpice环境中完成了电路的时域和频域仿真分析,对影响振荡电路起振特性的因素进行了探讨,进一步验证了PSpice电路仿真设计的合理性和可靠性。给出了发生电路的振荡、稳幅波形,测量了振荡周期和振荡频率,并与理论值做出比较。结果表明,设计的振荡电路波形好,振荡频率稳定,易于实现,可广泛应用于工程设计领域。     

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.     

New voltage-mode universal filter and sinusoidal oscillator using only single DBTA

In this article, a new voltage-mode second-order universal frequency filter and sinusoidal oscillator using only single differential-input buffered and transconductance amplifier (DBTA) is presented. The proposed voltage-mode filter structure using single DBTA and four passive elements can provide all standard filter functions, i.e. low-, band-, high-pass, band-stop, and all-pass without changing the circuit topology and enables independent control of the quality factor Q using single passive element. The circuit requires the minimal number of active and passive elements with no conditions for component matching. By slight modification of the proposed filter structure, the new DBTA-based sinusoidal oscillator is easily obtained. The oscillation condition and the oscillation frequency are independently adjustable by different virtually grounded passive elements. The proposed sinusoidal oscillator employs only grounded capacitors. The passive and active sensitivities of all the proposed circuit configurations are low. PSPICE simulations using a BJT realisation of DBTA and experimental results based on commercially available amplifiers OPA860 and MAX436 are included, which prove the workability of the proposed circuits.     

Theoretical Analysis of Novel Multi-Order LC Oscillators

A conventional differential pair LC oscillator is capable of generating only a single fundamental oscillation frequency. This brief presents the theoretical study of a novel oscillator that incorporates higher order LC filters to produce multiple oscillation frequencies that may be several octaves apart. These multiple oscillation frequencies are obtained from a single oscillator, thereby reducing the area of the circuit when being used for multistandard wireless applications. Moreover, a multi-order oscillator does not suffer from large parasitic capacitances from switches, which is a common drawback in switched-inductor tuned oscillators. A detailed analysis is carried out, and useful design insights are provided     

A novel variable frequency sinusoidal oscillator using a single current conveyor

A new active RC second-order sinusoidal oscillator using a single second generation current conveyor is described. A single grounded resistor adjusts the circuit for oscillation and a single grounded capacitor controls the oscillation frequency without affecting the oscilllation condition.     

A GaAs MESFET Self-Bias Mode Oscillator (Short Paper)

A self-bias mode oscillation in a GaAs MESFET, with the gate terminal kept open in a dc manner, has been analyzed by a large-signal MESFET circuit model. The circuit simulation demonstrates that the gate-source Schottky barrier becomes self-biased along with the microwave oscillation build-up and that a stable self-bias gate voltage is observed with a steady-state oscillation. A self-bias mode oscillator, operable with a single positive dc bias, is realized by rising microwave integrated circuit technology.