Tunable active allpass sections

Two second-order allpass circuits are described, realising a pair of complex poles (and matching zeros) by analogue simulation. The group-delay response can be made to be essentially dependent on only two network parameters whose values can be selected to `tune? to a particular characteristic.     

Mixer for low voltage operation

A very high conversion gain mixer of frequency 350 MHz is designed using the injection-locked technique. The mixer is based on a common-base Clapp oscillator which is free-running at a frequency of 350 MHz. Using the injection-locked technique, the nonlinear resistance of the oscillator is modulated by the injection source which provides negative resistance amplification to the RF signal. It gives conversion gain as high as 30 dB with good noise performance     

Complex notch filter design using allpass filter

Complex coefficient IIR notch filter design problems are investigated. The specification of a notch filter is first transformed into that of an allpass filter. An effective approach to the design of this desired allpass filter is developed. The realisation of the proposed notch filter is equivalent to the realisation of an allpass filter. Owing to the mirror-image symmetry relation between the numerator and denominator polynomials of allpass filters, the notch filter can be realised by a computationally efficient lattice structure with very low sensitivity     

Tunable thin-film filter with low angle sensitivity

Conventional angle-tuned thin-film filters have serious angle sensitivity for their low spacer effective refractive index, and it is difficult to fabricate their angle control system. In this paper, we propose and fabricate a novel 100 GHz angle-tuned thin-film filter stack with low angle sensitivity, which uses the high refractive index material TiO2 as the spacer, and its incident angle can be expanded to 25°. Compared with the traditional Ta2O5-SiO2 thin-film filter stack, the novel stack has fewer layers. Using the polarization beam splitters and the half wave plates, the polarization sensitivity of the angle-tuned filter can also be suppressed. Simulation results and the experiments show that the thin-film filter with low angle sensitivity has an effective tuning range of 33 nm, which can cover the whole C-band, and its angle control system is easy to be fabricated.     

A novel first-order log-domain allpass filter

This paper proposes a first-order allpass log-domain filter, which is systematically derived using the state-space synthesis procedure. To the best knowledge of the authors, the filter is the first log-domain first-order allpass filter in the literature. The proposed filter has a simple structure and can be electronically tuned. PSPICE simulations are given to confirm the theoretical analysis.     

First-order allpass filter using multi-input OTA

A novel first-order allpass filter, operating in voltage-mode, is introduced in this article. Compared with the corresponding already proposed structures, attractive offered benefits are the capability for simultaneous offering a minimum number of active and passive components, and the absence of any realisability restriction. These have been achieved by employing a multiple-input operational transconductance amplifier as active element. The performance of the proposed circuits has been evaluated through simulation results, utilising the Analog Design Environment of Cadence software.     

Efficient tunable IIR and allpass filter structures

A new recursive filter structure is proposed which can be controlled on-line using a single parameter. The structure can be used for interpolation in timing synchronisation of digital communications receivers. The technique is illustrated with an example of the implementation of a tunable fractional delay allpass filter using the Thiran design technique     

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.     

First-order allpass filter and sinusoidal oscillators using DDCCs

A voltage-mode first-order allpass filter using one differential difference current conveyor (DDCC), one grounded capacitor and one floating resistor is presented. No passive component matching constraints are required. Because the output impedance of the proposed allpass filter is low, the output terminal can be directly connected to the next stage. Using the proposed first-order allpass filter as a basic building block, a new quadrature oscillator and even-phase sinusoidal oscillators can be obtained. The simulation results confirm the theoretical analysis.     

Interpolated LIR Mth-band filter design with allpass subfilters

We propose a new allpass-based structure for the IIR Mth-and 2Mth-band filters. These filters consist of M allpass filters and an interpolation filter (sum of two allpasses). Consequently, the proposed structure is very efficient in implementation. By choosing the allpass phase appropriately, the resulting phase response of the IIR Mth-band filter becomes approximately linear. An example is designed and compared with FIR Mth-band filters     

Single MIMO-OTA and single-grounded-capacitor-based first-order allpass filter design

A novel first-order voltage-mode allpass (AP) filter employing a single multiple-input-multiple-output operational-transconductance-amplifier (MIMO-OTA) and a single grounded capacitor is introduced in this article. Compared to the corresponding already published topologies, the offered benefits are as follows: it employs minimum number of active and passive components; the only capacitor is grounded, which is good for a monolithic integration of an IC; and the absence of any matching condition for its realisability. The performance of the proposed circuit has been evaluated through simulation results, utilising the analogue design environment of Cadence software.     

Adjustable coupled two-cavity allpass filter for dispersion slopecompensation of optical fibres

The filter gives variable compensation between -2.0 and -15.5 ps ³ over a bandwidth between 3.6 and 1.2 nm, respectively. The filter performance agrees quite well with that predicted by existing theory     

New complex-pole single-amplifier allpass filter with reduced active-element sensitivities

A new complex-pole allpass network is described which is based on the minimum-transmission properties of an RC parallel-T network. The proposed structure is compared with the canonic Deliyannis arrangement, and analytical and experimental evidence is presented which indicates an improved sensitivity to finite-amplifier-gain effects.     

Approaches to extra low voltage DRAM operation by SOI-DRAM

The newly designed scheme for a low-voltage 16 MDRAM/SOI has been successfully realized and the functional DRAM operation has been obtained at very low supply voltage below 1 V. The key process and circuit technologies for low-voltage/high-speed SOI-DRAM will be described here. The extra low voltage DRAM technologies are composed of the modified MESA isolation without parasitic MOS operation, the dual gate SOI-MOSFETs with tied or floating bodies optimized for DRAM specific circuits, the conventional stacked capacitor with increased capacitance by thinner dielectric film, and the other bulk-Si compatible DRAM structure. Moreover, a body bias control technique was applied for body-tied MOSFETs to realize high performance even at low voltage. Integrating the above technologies in the newly designed 0.5-μm 16 MDRAM, high-speed DRAM operation of less than 50 ns has been obtained at low supply voltage of 1 V     

Tunable superconducting microstrip filter

An electrically tunable two-pole bandpass filter with incorporated superconductor (YBaCuO) and nonlinear dielectric (SrTiO₃) films has been designed and investigated. The filter layout and DC voltage tuning of the filter frequency response are presented     

The design of low voltage/power current-mode sinh-domain filter for biomedical applications

This paper proposes low voltage/power, current-mode second-order Butterworth high-pass filter design in the sinh-domain for biomedical applications. The proposed filter is a continuous-time filter in the companding-class. Sinh-domain filters have the advantages of electronically adjusting the frequency response without the need for non-chip capacitors and full integration on the chip, providing low power consumption and offering a high dynamic range. These advantages of the sinh-domain are beneficial for biomedical applications due to its low power consumption requirement. The proposed filter topology is suitable for eliminating low-frequency interferences of biomedical signals like electrocardiogram (ECG), electroencephalogram (EEG), and electromyogram (EMG). In the realization of this filter, the method of simulation of passive elements with sinh-domain cells is used. The proposed high-pass filter in the 0.05 Hz-20 Hz operating frequency range with a 0.5 V power supply shows the power dissipation of 12.5 nW while its dynamic range exceeds 60 dB. Additionally, no resistances are used in the proposed topology. Simulations have been performed by using OrCAD Capture CIS to demonstrate the performance of the filter. These simulations have been implemented with the TSMC 0.25 µm CMOS process parameters.

     

Tunable bandstop MEMS filter for millimetre-wave applications

The design and realisation of original millimetre-wave tunable bandstop filters using MEMS (micro-electro-mechanical-systems) technology for millimetre-wave applications is presented. The tunable behaviour is achieved by using MEMS switches. The overall structures, including the MEMS switches, have been manufactured using dielectric membrane in order to minimise the dielectric losses. Experimental validations are reported and validate the proposed topology: the bandstop frequency is shifted by approximately 3.5 GHz in V-band when the switches are actuated     

低电压驱动的MEMS F-P可调光学滤波器研究

基于微机电系统（MEMS）技术,研制了一种新颖的光学腔与静电驱动器分离的Fabry-Pérot（F-P）可调谐滤波器。从光学设计、MEMS结构设计、制造工艺与器件测试等开展了F-P可调谐滤波器的研究,成功制备了工作在以1550 nm波长为中心、调谐范围为40 nm和驱动电压低于30 V的MEMS F-P可调滤波器。测试...     

CNTFET based voltage differencing current conveyor low power and universal filter

Analog Integrated Circuits and Signal Processing - This paper presents carbon nanotube field effect transistor (CNTFET) implementation of voltage differencing current conveyor (VDCC). We propose...     

Cascadable allpass filter with a single DO-CCII and a grounded capacitor

In the literature sufficient emphasis has not been given to dual-output current conveyors in all-pass filter designs. In this study, a cascadable voltage-mode all-pass filter with a grounded capacitor using a single dual-output current conveyor has been reported.