Log-domain All-pass Filter-based Multiphase Sinusoidal Oscillators

Log-domain current-mode multiphase sinusoidal oscillators based on all-pass filters are presented in this paper. The first-order differential equation is used for obtaining inverting and non-inverting all-pass filters. The proposed oscillators are realized by all-pass filters which can be electronically tuned their natural frequency and stage gain by adjusting the bias currents. Each all pass filter contains 10 NPN transistors and a grounded capacitor. The validated BJT model which used in SPICE simulation operated by a single power supply as low as 2.5 V. The frequency of oscillation can be controlled over four decades. The total harmonic distortions of these MSO at frequency 56.67 MHz and 54.44 MHz, obtained around 0.52% and 0.75%, respectively. The proposed circuits enable fully integrated in telecommunication systems and also suit to high-frequency applications. Nonideality studies and PSpice simulation results are included to confirm the theory

Single-input Multiple-output Tunable Log-domain Current-mode Universal Filter

This paper describes the design of a current-mode single-input multiple-output (SIMO) universal filter based on the log-domain filtering concept. The circuit is a direct realization of a first-order differential equation for obtaining the lossy integrator circuit. Lossless integrators are realized by log-domain lossy integrators. The proposed filter comprises only two grounded capacitors and twenty-four transistors. This filter suits to operate in very high frequency (VHF) applications. The pole-frequency of the proposed filter can be controlled over five decade frequency range through bias currents. The pole-Q can be independently controlled with the pole-frequency. Non-ideal effects on the filter are studied in detail. A validated BJT model is used in the simulations operated by a single power supply, as low as 2.5 V. The simulation results using PSpice are included to confirm the good performances and are in agreement with the theory

Electronically Tunable Current-mode Multiphase Sinusoidal Oscillator Employing CCCDTA-based Allpass Filters with Only Grounded Passive Elements

This study describes the design of a multiphase sinusoidal oscillator (MSO) using CCCDTA-based allpass filters with grounded capacitors. The oscillation condition and oscillation frequency can be electronically/orthogonally controlled. The proposed MSO provides 2n (n>2) phase signals that are equally spaced in phase and of equal amplitude. The circuit requires one CCCDTA, one electronic resistor and one grounded capacitor per phase and no additional current amplifier and floating elements. High output impedances of the configuration enable the circuit to be cascaded to the current-mode circuit without additional current buffers. The effects of the non-idealities of the CCCDTA-allpass sections were also studied. The results of PSPICE simulations using CMOS CCCDTA are presented, demonstrating their consistency with theoretical assumptions

Electronically Tunable Current-mode High-order Ladder Low-pass Filters Based on CMOS Technology

This paper describes the design of current mode low-pass ladder filters based on CMOS technology. The filters are derived from passive RLC ladder filter prototypes using new CMOS lossy and lossless integrators. The all-pole and Elliptic approximations are used in the proposed low-pass filter realizations. The proposed two types of filter can be electronically tuned between 10kHz and 100MHz through bias current from 0.03µA to 300µA. The proposed filters use 1.5 V power supply with 3 mW power consumption at 300 µA bias current. The proposed filters are resistorless, use grounded capacitors and are suitable for further integration. The total harmonic distortion (THD) of the low-pass filters is less than 1% over the operating frequency range. PSPICE simulation results, obtained by using TSMC 0.18µm technology, confirm the presented theory

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

This document is the Accepted Manuscript version of the following article: Hu, Z., Wang, C., Sun, J. et al. ‘A wideband linear tunable CDTA and its application in field programmable analogue array’, Analog Integrated Circuits and Signal Processing, Vol. 88 (3): 465-483, September 2016. Under embargo. Embargo end date: 6 June 2017. The final publication is available at Springer via https://link.springer.com/article/10.1007%2Fs10470-016-0772-7 © Springer Science+Business Media New York 2016In 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.Peer reviewedFinal Accepted Versio

Intra-channel Interference Avoidance with the OGFDM Boosts Channel Capacity of Future Wireless Mobile Communication

The Orthogonal Generalized Frequency Division Multiplexing (OGFDM) with Intra-Channel Interference Avoidance (ICIA) approach is, for the first time, proposed, explored and evaluated. Since the interference manipulation currently represents a hot topic for wireless mobile communication, the conventional approach of mitigating the interference is no longer acceptable. As a result, a novel method for addressing the interference between adjacent filtered sub-carriers (in-phase/out-phase) is comprehensively investigated herein. The proposed approach utilises the oversampling factor to effectively avoid interference and improve the quality of service of affected filters under bad transmission states. Thus, this supportive method which is essentially aware of propagation conditions is employed for removing the roll-off ( α ) impact yet improving the level of Bandwidth (BW) efficiency for applied filters of the OGFDM waveform. Besides, in terms of the system performance, the trade-off relation between the channel capacity and the key Hilbert filter parameter is theoretically and practically discussed. This requires investigation of the influence of α factor on the maximum achieved bit-rate at the acceptable limit of the Bit Error Rate (BER). A MATLAB simulation was introduced to test the performance characteristics of the proposed system in the physical layer (PHY) of an electrical back-to-back wireless transmission system

Log-domain All-pass Filter-based Multiphase Sinusoidal Oscillators

Log-domain current-mode multiphase sinusoidal oscillators based on all-pass filters are presented in this paper. The first-order differential equation is used for obtaining inverting and non-inverting all-pass filters. The proposed oscillators are realized by all-pass filters which can be electronically tuned their natural frequency and stage gain by adjusting the bias currents. Each all pass filter contains 10 NPN transistors and a grounded capacitor. The validated BJT model which used in SPICE simulation operated by a single power supply as low as 2.5 V. The frequency of oscillation can be controlled over four decades. The total harmonic distortions of these MSO at frequency 56.67 MHz and 54.44 MHz, obtained around 0.52% and 0.75%, respectively. The proposed circuits enable fully integrated in telecommunication systems and also suit to high-frequency applications. Nonideality studies and PSpice simulation results are included to confirm the theory