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A fourth-order Butterworth active Gm-C complex IF filter for dual-mode GNSS receiver is presented. This filter operates at center frequency of 7.161MHz and in bandwidth of 4MHz with pass-band gain of over 10dB and image rejection of over 35dB, which meets requirements of BD2 and Galileo Systems. The proposed CMOS fully differential transconductor has wide tuning range, high linearity and low power...
Abstract-Design of high-performance continuous- time filter (CTF) for analogue signal processing is presented in this paper. To demonstrate of using a novel voltage-mode multiple-loop feedback (MLF) approach for CTF design, a 5th-order elliptic lowpass filter (LPF) is implemented in a standard 0.18-µm CMOS technology. The LPF is based on an inverse-follow-the-leader feedback structure with an input...
In this paper a novel simple all digital frequency locking circuit design is presented together with its performance results. The proposed method can be used to lock DDSs to a reference clock such as a data clock. It allows for efficient fully multi-rate modem design (with a resolution bound by the DDS) within a low cost FPGA. In fact, using the new scheme the baseband modem can be completely constructed...
A coefficient vector technique implemented on a differential distributed space time block coding (DDSTBC) scheme is presented in this paper to improve on the computation complexity of existing DDSTBC schemes. The full mapping scheme and differential technique for utilizing the co-efficient vectors in a two-relay cooperative network is presented and comparison is made between the proposed technique...
For a multiuser multiple-input-multiple-output (MIMO) overlay cognitive radio (CR) network, a spacetime opportunistic interference alignment (ST-OIA) technique has been proposed that allows spectrum sharing between primary users (PU) and secondary users (SU) while ensuring zero interference to the PU. The CR system consists of one primary user (PU) and K secondary users (SU) where local channel state...
This paper focuses on the quantization of soft decision based cooperative spectrum sensing (CSS). The soft data fusion CSS schemes in previous research works provide considerable enhancement in the probability of detection, but at the expense of increased bandwidth required for transmitting the sensing measurements to the Fusion Center (FC). In this paper, Maximum likelihood Estimation (MLE) statistics...
An adaptive broadband antenna tuning technique using quantum genetic algorithms is proposed in this paper. This method is fast and can achieve a global optimal solution. It is useful for software defined radio systems using a single antenna for multiple mobile and wireless bands. Simulations have been conducted using GSM, UMTS and both standards, with different antenna impedances. The frequency band...
Cognitive radio has become an effective technology to solve the underutilisation problem of the spectrum. In recent times, spectrum sensing has been intensively studied as a key technology in realising the cognitive radio. In this paper, we consider an amplify-and-forward relay-based cooperative spectrum sensing using a double threshold energy detector. Each secondary cognitive user takes a local...
Present day requirements of high quality audio and video surveillance has instigated research interests in wireless multimedia sensor networks (WMSN). In order for the WMSN to achieve trademark performance in audio and video surveillance applications, certain design requirements must be met. In this work, we identify vital design issues affecting diversity gain in conditions especially, where channel...
This paper investigates adaptive zero-forcing (ZF) uplink transmission for a large-scale multi-user multi-antenna (MUMA) system. It is assumed that power control can be done at these transmitters as channel condition changes, and the number of antennas at the base station (BS) is not less than the number of users with each having single antenna. Under the case where both individual user rates and...
Cooperative Spectrum Sensing has been investigated in Rayleigh-fading environments over non-ideal reporting channels, where the simulation results have shown that its performance is limited by the probability of reporting errors. This paper proposes a transmit diversity scheme using Differential Space-Time coding where channel state information is not required. By regarding multiple pairs of Cognitive...
A 0.5–30GHz wideband differential CMOS T/R switch is proposed with low insertion loss (IL), high power handling capacity and high TX-RX isolation. The independent bias technique is proposed to keep the transistors in ideal on/off mode to improve IL and power handling capacity. The leakage cancellation technique is introduced to cancel leakage from TX port to RX port with two match paths. The proposed...
A fully-integrated Sub-GHz low-power transceiver (TRX) for 802.11ah applications is presented. The receiver takes both advantages of Low-IF/Zero-IF architectures while supporting 1/2/8MHz reconfigurable signal bandwidth. A Σ-Δ fractional-N PLL with Class-C VCO is employed to provide the LOs. In order to enhance the power amplifier (PA) back-off efficiency, a Peak-to-Average-Power-Ratio (PAPR) tolerant...
A fully integrated reconfigurable transceiver (TRX) in 180nm CMOS for 750–960MHz narrowband applications is presented. The low-cost TRX consists of a low-IF receiver with 180 kHz signal bandwidth, a digital polar transmitter with 3.75 kHz signal bandwidth and a fractional-N frequency synthesizer. The receiver features a passive current mode mixer to improve the linearity and avoid the noise degradation...
A 4th-order quadrature bandpass continuous-time sigma-delta modulator for a GNSS receiver is presented. With significantly wide bandwidth, the modulator is able to digitalize the down-conversed GNSS signals in two adjacent signal bands simultaneously. This makes it possible to realize simultaneous dual-frequency reception from two satellite systems with one receiver channel instead of two independent...
Energy harvesting has been widely considered in many wireless applications, especially the wireless sensor networks. This paper develops a novel approach to energy-harvesting powered transmissions under arbitrary packet arrival process and strict deadline constraints over time-varying channels. It is shown that the problem can be formulated as a convex program. Relying on the specific structure of...
In this paper, a source-assisting differential distributed space time block coding (SA-DDSTBC) scheme is proposed for cooperative networks. Firstly, in most existing works on distributed space time block coding (DSTBC), the destination node is assumed to have perfect channel state information (CSI), thus, signal recovery is straight forward. In practice however, some scenarios exist whereby the destination...
A method is proposed to realize high-frequency wavelet transform in analogue filter by employing Gm-C circuits and current-mode leap-frog multiple loop feedback structure in this paper. Also, to enhance the performance, the fully differential Nauta transconductor is utilized as the Gm cell in the design. The Marr wavelet is used as an example, with the design procedure illustrated. Using standard...
A CMOS fifth-order Gm-C elliptic lowpass filter based on the voltage-mode multiple loop feedback (MLF) leap-frog (LF) configuration is designed. The filter is implemented using a fully-differential linear operational transconductance amplifier (OTA). PSpice simulations using a standard TSMC 0.18µm CMOS process with 1.8V power supply have shown that the cut-off frequency of the proposed filter can...
This paper outlines the popular circuit tuning strategies reported for the implementation of reconfigurable low-noise amplifiers (LNAs). It presents a continuously-tuned LNA intended for multi-standard applications as well as enhancing the yield of conventional narrowband LNAs. The presented LNA is designed and implemented in a 0.25μm silicon-on-sapphire (SOS) CMOS process. It uses MOS-varactors at...
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