Current-Controlled CFTA Based Fractional Order Quadrature Oscillators

This paper presents a study of fractional order quadrature oscillators based on current-controlled current follower transconductance amplifiers (CCCFTA). The design realisation and performance of the fractional order quadrature oscillators have been presented. The quadrature oscillators are constructed using three fractional capacitors of orders α = 0.5. The fractional capacitor is not available on the market or in the PSPICE program. Fortunately, the fractional capacitor can be realised by using the approximate method for the RC ladder network approximation. The oscillation frequency and oscillation condition can be electronically/orthogonally controlled via input bias currents. Due to high-output impedances, the proposed circuit enables easy cascading in current-mode (CM). The PSPICE simulation results are depicted, and the given results agree well with the anticipated theoretical outcomes.

Pathological Models of EXCCCII and Its Applications in Oscillator Synthesis

After giving six different forms of the extra X second-generation current-controlled conveyor(EXCCCII),pathological models of six EXCCCIIs are found by the nodal admittance matrix(NAM)expansion approach.Furthermore,these ideal pathological circuit models are employed and 36 Wien oscillators and 8 third-order quadrature oscillators are synthesized by the NAM expansion.The hand analysis and computer analysis are introduced to prove the synthesized circuits are correct and effective.

A code-aided carrier synchronization algorithm based on improved nonbinary low-density parity-check codes

In order to further improve the carrier synchronization estimation range and accuracy at low signal-to-noise ratio(SNR), this paper proposes a code-aided carrier synchronization algorithm based on improved nonbinary low-density parity-check(NB-LDPC) codes to study the polarization-division-multiplexing coherent optical orthogonal frequency division multiplexing(PDM-CO-OFDM) system performance in the cases of quadrature phase shift keying(QPSK) and 16 quadrature amplitude modulation(16-QAM) modes. The simulation results indicate that this algorithm can enlarge frequency and phase offset estimation ranges and enhance accuracy of the system greatly, and the bit error rate(BER) performance of the system is improved effectively compared with that of the system employing traditional NB-LDPC code-aided carrier synchronization algorithm.

Design of 25 Gbit/s half-rate CDR with 1:2 demultiplexer for 100 GbE optical interconnects

A 25 Gbit/s clock and data recovery （CDR） circuit with 1：2 demultiplexer for 100 Gbit/s Ethemet （100 GbE） optical interconnects has been designed and fabricated in Taiwan Semiconductor Manufacture Company （TSMC） 65nm complementary metal-oxide-semiconductor （CMOS） technology. A novel quadrature voltage-controlled-oscillator （QVCO） structure adopts two pairs of transconductance cell and inverters to acquire rail-to-rail output swing. A half-rate bang-bang phase detector adopts four flip-flops array to sample the 25 Gbit/s input data and align the data phase, so the 25 Gbit/s data are retimed and demultiplexed into two paths 12.5 Gbit/s output data. Experimental results show that the recovered clock exhibits a peak-to-peak jitter of 7.39 ps and the recovered data presents a peak-to-peak jitter of 7.56 ps, in response to 231 - 1 pseudorandom bit sequence （PRBS） input. For 1.2 V voltage supply, the CDR circuit consumes 92 mW （excluding output buffers）.

Generation of optical frequency comb squeezed light field with TEM_(01) transverse mode

Nonclassical optical frequency combs find tremendous utility in quantum information and high-precision quantum measurement. The characteristics of a type-I synchronously pumped optical parametric oscillator with the TEM_（01） transverse mode below threshold are investigated and a squeezing of 0.7 dB for an optical frequency comb squeezed light field with the TEM_（01） transverse mode is obtained under the pump power of 130 m W. This work has a promising application in three-dimensional space-time measurement.