A fully integrated tunable 4th-order multi-feedback bandpass delta-sigma modulator (BPDSM) fabricated in 0.25um SiGe BiCMOS is presented. The input frequency can be tuned from 945MHz to 988MHz at 2.4GHz fixed clock frequency. This modulator dissipates 110mA from 3.3V power supply. The peak signal-to-noise-ratio (SNR) of sinewave input is 41.1dB in 10MHz bandwidth and error vector magnitude (EVM) of 64QAM long term evolution (LTE) downlink is 3.16%, 3.59%, and 3.65% at different carrier frequencies.
Advancement of superconductor digital electronics, especially Rapid Single Flux Quantum (RSFQ) logic circuit is described. Ultra short pulse of a voltage generated across a Josephson junction and release from charging/discharging process for signal transmission in RSFQ circuits enable us to reduce power consumption and gate delay. The power-delay products (PDPs) of RSFQ integrated circuits (ICs) are 4 or 5 orders of magnitude smaller than those of semiconductor ICs. The fabrication process technology and the related designing technology have been advanced, and RSFQ ICs have been applied to software-defined radio receivers, superconductor detector array systems, and supercomputers. Recently, several kinds of energy-efficient single flux quantum circuit have been proposed to obtain further advantage to semiconductor devices. The PDPs of these circuits become at least 1 order smaller than those of conventional RSFQ circuits.
Digital watermarking is an innovative technique for intellectual property protection (IPP) of Field Programmable Gate Array (FPGA) designs. However, many of these techniques usually need manually extract marks from binary bit-files by the FPGA tool or exhaustive search to find out marks in the design, which results in inefficiency of the watermark verification. This paper presents a method to fast verify the authorship through extracting the content of the watermarked lookup tables from a binary bit-file. We demonstrate the proposed method on several Xilinx Virtex-II devices, and experimental results on the watermarked designs from the IWLS 2005 benchmarks show that the verification of authorship has high efficiency.
This paper presents the design of a lowpass filter (LPF) with high and ultra wide rejection in the stopband using stepped-impedance compact microstrip resonator cell (SICMRC). The proposed filter consists of a prototype stepped-impedance LPF, which is modified to form a double arrow shaped microstrip cell (DASMC) with a wide stopband. Then, SICMRC is embedded in the structure of the DASMC to obtain a sharp response. The attenuation level in the stopband is better than -20dB that is achieved from 6.6 to 41.7GHz. The proposed filter has low insertion loss less than 0.1dB and high return loss more than 26dB in the passband. The transition band is approximately 0.74GHZ from 5.86 to 6.6GHz with corresponding attenuation levels of -3 and -20dB. The cut-off frequency of the prototype filter is 5.8GHz. It has a simple shape and a compact size of 14.2mm × 8.2mm. The proposed filter has been designed, fabricated and measured. The Comparison between the simulation and experimental results shows that they are in good agreement.
A meandered uniplanar compact electromagnetic band-gap structure is proposed. Meandered microstrip lines between adjacent cells are used to increase the equivalent inductance. As a result, the dimension of the proposed EBG structure is more compact and its frequency band-gap is wider than that of the conventional uniplanar EBG structure. Two patch arrays with and without an EBG structure were designed, fabricated, and tested to validate the performance of the proposed EBG structure. The measured results demonstrated that a mutual coupling reduction of 4dB is achievable in a patch array with the proposed EBG structure.
This work presents an ultra-low-power, biologically inspired pseudo-random number generator based on the Hodgkin-Huxley silicon neuron circuit. The chaotic phenomenon observed in neurons is exploited to generate random numbers. The random sequence generated by the proposed system passed the statistical tests specified by Federal Information Processing Standard. The proposed random number generator circuit provides an ultra-low-power alternative for pseudo-random number generation with 180nW power consumption.
Recently, compact wireless modules are very significant parts for multi-band wireless systems such as mobile phones and compact personal computers. A low temperature co-fired ceramic (LTCC) substrate which has embedded passive components is effective technology for producing the compact modules, because this substrate is suitable for a multilayer structure and is also a low dielectric loss and a low conductor loss. Therefore, a lot of multi-band wireless systems use this technology. In the radio frequency circuits of the multi-band wireless systems, a multiplexer is one of the most important passive circuits, in order to achieve both a compact size and high performances. In this paper, we report the technology of the compact multiplexer modules using the LTCC substrate. This paper especially focuses on the multiplexer for ultra-wideband wireless systems. The multiplexer which is suitable for narrow band wireless systems is also described.