Order Current-mode Research Articles

4th order current-mode and transresistance-mode MOSFET-C low-pass filter for multi-standard receivers

This work presents a novel 4th order current-mode and transresistance-mode low-pass filter based on MOSFET-C architecture. Proposed filter's cut-off frequency can be easily adjusted from 15 MHz up to 45 MHz for the analog baseband filters used in multi-standard receivers. The main core circuit of the filter contains only 7 transistors in order to reduce chip area and power consumption. Also, the proposed 4th order architecture have dual outputs in different modes facilitating signal conversion and different signal operations. The proposed structure has (54.3 μm × 34.1 μm) chip area and post layout simulations are examined extensively to prove performance of the filter. Also, input referred noise (IRN) characteristics of the filter outputs are shown in order to overcome thermal noise effects worsening the performance of the filter. Power consumption changes from 195.8 μW up to 1.37 mW whereas cut-off frequency is varied from 15 MHz up to 45 MHz. Provided results show that the proposed filter scheme brings a promising opportunity to designers for the analog baseband operations in multi-standard communication receivers.

CMOS Realization of VDTA Based Electronically Tunable Wave Active Filter with Minimum Power Consumption at Low Supply Voltage ±0.82 V

This paper presents a higher order voltage and current mode low pass or high pass filter for wave active filter based on Voltage Differencing Transconductance Amplifiers (VDTAs). The wave equivalent variable technique and topological simulation as well as operational realization using wave variables techniques are proposed for basic active building blocks of wave active filters. The proposed wave equivalent technique is employed for wave active filter with the proper selection of the terminal connections. This work presented the basic element for the realizing wave active filter is the series inductor with parallel grounded capacitor. The proposed wave active filter is verified by realizing a 4th order low pass and high pass Butterworth filter with minimum power consumption at ±0.82 V using SPICE simulation with 0.18 μm TSMC CMOS technology parameters.

Novel First Order Current Mode MOS-C Phase Shifters

In this work, novel first order MOS-C phase shifter structures are proposed in NMOS and PMOS configurations. Core circuits consist of only three transistors and a single capacitor. The pole frequency of the phase shifters can be easily controlled by the bias voltage. The presented circuits in this work bring advantages such as low power consumption and small chip area when compared to other works including large numbers of active and passive elements in the literature. Furthermore, the proposed circuits are designed with a simple design automation flow that is proper for MOS-Only or MOS-C architectures. It is shown by simulations that the simulation results agree with the theoretical results for a wide frequency range. DOI: http://dx.doi.org/10.5755/j01.eie.24.1.20157

Single CFTA Based Current-Mode Universal Biquad Filter

This paper introduces a new current-mode (CM) universal biquad filter structure with optimum number of active and passive elements. In the design, the proposed circuit uses a single active element namely, current follower trans-conductance amplifier (CFTA) and two grounded capacitors as passive elements. The main feature of the proposed circuit is that it can realize all five standard filtering functions such as low pass (LP), band pass (BP), high pass (HP), band stop (BS) and all pass (AP) responses across an explicit high impedance output terminal through the appropriate selection of three inputs. In addition, the same circuit is also capable to simultaneously realize three filtering functions (LP, BP and HP) by the use of single current input signal. Moreover, the proposed structure is suited for low voltage, low power operations and offers the feature of electronic tunability of pole-frequency and quality factor. Further to extend the utility of the proposed circuit block higher order current-mode filters are also realized through direct cascading. A detailed non-ideal and parasitic study is also included. The performance of the circuits has been examined using standard 0.25 μ m CMOS parameters from TSMC.

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.

Current mode sigma-delta modulator designed with the help of transistor’s size optimization tool

Abstract The paper presents a second order current mode sigma-delta modulator designed with the help of a new elaborated tool to optimize the transistor sizes. The circuit is composed of two continuous time loop filters, a current comparator and a one bit DAC with a current output. The resulting circuit, designed in a 65 nm 1.2 V CMOS technology, has a bandwidth of 2 MHz for a clock frequency of 250 MHz. The electrical simulation results show that it achieves a maximum signal-to-noise-plus-distortion ratio (SNDR) of 53.6 dB while dissipating 93 μW, which corresponds to an efficiency of 59.7 fJ/conv. The fully current mode structure makes the circuit suitable to be applied in a current mode signal processing like biosensors or image pixels arrays.

MOSFET-only multi-function biquad filter

In this paper, using only seven MOS transistors, second order current-mode LP/BP filter is proposed. The transconductances of the MOS transistors in saturation region are used instead of passive resistors and gate-to-source capacitances are employed instead of passive capacitors. The proposed circuit exhibits important features such as simplicity, reduced chip area and wide frequency range compared to classical analog circuits that require active elements including large number of transistors. Layout of the proposed circuit is drawn using Mentor Graphics IC Station layout editor. AMS 0.35μm process parameters are used during post-layout simulations.

A Novel Approach for Realization of Higher Order Filter using Bipolar and MOS Current-Mirrors

In this paper, we have presented an approach to realize higher order current-mode filters using cascade technique of lower order filters realized using CMOS current-mirrors. This paper presents the realization of higher-order low-pass (LP) active current-mode filters using cascade technique of second and third order filters. Interest in current-mode (CM) filters has been growing due to the fact that current-mode devices have wider dynamic range, improved linearity, and extended bandwidth as compared to their voltage- mode counterparts. In the sub-micron era of semi-conductor technology, the minute structure of devices causes a high electric field and thus the power supply voltage is limited to a certain low value to protect the device from destruction. Current-mode signal processing is quite attractive for operation at high frequencies and low power supply voltage operation from the viewpoint of sub-micron era. The realized filters do not contain any resistors, therefore simplifying the pattern of integrated circuits and thus reducing the chip area and the cost. The proposed circuits presented in the paper using bipolar technology and CMOS technology were tested in SPICE using BJT model NR100N and PR100N and the MOS structure using 0.5µm CMOS process parameters provided by MOSIS (AGILENT) and the results thus obtained were in accordance with the theoretical values.

Universal Biquadratic Filter Employing Single Differential Voltage Current Controlled Conveyor Transconductance Amplifier

This paper presents new realizations of second order voltage mode and current mode universal filters based on a recently reported active element, called the differential voltage current controlled conveyor transconductance amplifier (DVCCCTA). The proposed circuits do not use external resistor. The filter circuits provide all the responses without changing the circuit topology. All the capacitors are virtually grounded. The use of grounded capacitors makes the circuit suitable for monolithic implementation. The pole frequency and quality factor can be adjusted independently with the input bias currents. The non-ideal analysis and the sensitivity analysis have been included. Both the active and passive sensitivities are not more than unity. The filter performances are verified using the PSpice simulations which agree well with theoretical value. 

MOS-only second order current-mode LP/BP filter

In this study, a current-mode dual output low-pass and band-pass filter is presented using only six MOSFET transistors in its core. Transconductances and gate-to-source capacitances of the MOS transistors are employed instead of passive resistors and capacitors. The proposed circuit exhibits important features such as simplicity, low-voltage/power operation, reduced chip area and wide frequency range compared to classical analog circuits that require active elements with large number of transistors. Simulations are performed to verify the theoretical results.

Fully Controllable First Order Current Mode Universal Filter Composed of BJTs and a Grounded Capacitor

In this paper, a new BJT based configuration for providing first order current mode high-pass, low-pass and all-pass filter responses from the same configuration is suggested. The proposed circuit called as a universal filter possesses some important advantages such as consisting of low component count BJT and a grounded capacitor, having electronic tunability property of its pole frequency and having electronic controllability feature of filter types. The suggested circuit does not suffer from disadvantages of use of the resistors. Moreover, as an application, second order band-pass filter is also obtained by cascading two proposed filter structure. Simulations by means of PSpice program are accomplished to demonstrate the performance and effectiveness of the developed first-order universal filter. Approximately more than 1 decade tunability range is achieved. Ill. 7, bibl. 14, tabl. 3 (in English; abstracts in English and Lithuanian). http://dx.doi.org/10.5755/j01.eee.112.6.448

Electronically-Controlled Current-mode second order Sinusoidal Oscillators Using MO-OTAs and Grounded Capacitors

Five new electronically-controllable second order current-mode sinusoidal oscillators using three mul-ti-output operational transconductance amplifiers (MO-OTAs) and two grounded capacitors (GC) have been presented. Simulation results are included to confirm the theoretical analysis based upon CMOS OTAs implementable in 0.5 µm technology.

A UHF current-mode continuous-time band-pass delta sigma modulator using fully balanced active inductor

This paper introduces a 2 GHz continuous-time (CT) fourth order current-mode (CM) band-pass 0.18 μm CMOS delta sigma modulator (DSM) utilizing a fully balanced active inductor. The proposed active inductor takes advantage of positive feedback topology and features accurate loss compensation as well as independent tunability of quality factor and resonant frequency. Based on this active inductor, a CM Ultra High Frequency (UHF) resonator is also proposed, exhibiting a very small on-chip area. Moreover, a high speed CM quantizer working with one single clock is brought into eliminate the error introduced by clock generators. The post layout simulation of the DSM exhibits a peak SNDR of 43.6 dB at 500 MHz with a 40 MHz signal bandwidth while the center frequency can be tuned between 450 and 500 MHz. The measured results give an averaged SNDR of 33 dB with 40 MHz signal bandwidth, where the center frequency is tunable from 300 MHz to 350 MHz. This design consumes only 45 mW under 1.8 V power supply and occupies an area of 0.133 mm2.

Sustained Slow-Scale Oscillation in Higher Order Current-Mode Controlled Converter

DC-DC converters under current-mode control have been known to exhibit slow-scale oscillation as a result of a Hopf-type bifurcation as one or more of the parameters of the outer voltage loop are varied. In the absence of the outer voltage loop (i.e., open loop), slow-scale oscillation was generally not observed in simple low-order dc-dc converters, i.e., buck, buck-boost, and boost converters. In this paper, slow-scale bifurcation in a higher order current-mode controlled converter is studied. It has been found experimentally that, even in the absence of a closed outer voltage loop, a current-mode controlled Cuk converter can exhibit a slow-scale Hopf-type bifurcation. The phenomenon was observed in a commercial low-ripple dc-dc converter which has been designed using the Cuk converter and the LM2611 controller. Such slow-scale oscillation of the inner current loop can also be observed in full-circuit SPICE simulations. An averaged model has been developed and implemented in SPICE to find the Hopf bifurcation boundaries. With this averaged model, the Hopf bifurcation can be explained conveniently using the traditional loop gain analysis. Specifically, the extra degrees of freedom in higher order dc-dc converters have opened up a new possible mode of instability which has not been found in simple low-order dc-dc converters.

GROUNDED CAPACITOR CM-APS WITH HIGH OUTPUT IMPEDANCE

This paper presents a new first order current mode all-pass section (CM-APS) with a grounded capacitor and employing a modified current controlled conveyor. The new circuit with high output impedance is ideal for current-mode cascading and is tunable through an external bias current. The proposed circuit is unique due to its features, not exhibited by any of the available works on the topic. An application of the circuit in realizing a quadrature oscillator is also given. The theory is validated through PSPICE simulations using real device transistors.

On the Realization of Second Order Current Mode Active Filters Using Single Differential Voltage Current Conveyor (DVCC)

Article On the Realization of Second Order Current Mode Active Filters Using Single Differential Voltage Current Conveyor (DVCC) was published on May 1, 2003 in the journal Frequenz (volume 57, issue 5-6).

Insensitive voltage-mode and current-mode filters with easily modifiable transfer functions

Two configurations for 2nd order current-mode filters are introduced. The circuits, which exhibit low values for their active and passive sensitivies are implemented from two current conveyors. They are easily cascadable because they exhibit zero input impedance. Two voltage-mode implementations are then deduced from them. Depending on the passive components used, the circuit will be either a 2nd order or a 3rd order filter. Both the current-mode and voltage-mode implementations are characterized by easily modifiable transfer functions, without affecting ω0 and Q. SPICE simulation results, which confirm the theoretical analysis, are given and discussed for current conveyors implemented in a translinear form.

Novel translinear impedance convertor and bandpass filter applications

A new design for an impedance convertor using translinear elements is introduced. A custom integrated circuit for a gyrator can be implemented from it, using bipolar linear arrays. When the simulated impedance is an inductance, it can be used to design a second order current-mode filter with adjustable value for the Q-factor without affecting f0 and the gain. The effects of parasitic elements are studied. SPICE simulated results are given. They are in good agreement with theoretical results.