The characteristics of bulk-driven PMOS and quasi-floating-gate CMOS were discussed. Based on those techniques, two very low-voltage CMOS Mixers core were developed. When the power supply is 0.8 V,the oscillation frequency is 20 MHz and 100 MHz,the radio frequency is 1 G and 2.4 G,the conversion gain of bulk-driven is -17.95 dB and -8.5 dB, the IIP3 of bulk-driven mixer is (33.2 dB) and (28.4 dB). While the voltage is changed to 0.6 V,and other conditions are kept the same ,the conversion gain of quasi-floating-gate mixer is -14.23 dB and -21.8 dB, IIP3 of quasi-floating-gate mixer is 35.9 dB and 34.6 dB. According to the simulation result, the bulk-driven mixer has larger conversion gain, the quasi-floating-gate mixer has better frequency domain specification and characters of low-voltage. The two mixer are more fit for the scope of low frequency.
Aim To design temperature stability of 6H-SiC CMOS OPAMP.Methods Taking leakage current matching into account,Diode(Dcomp) is added to node A.According to ZTC and leakage current matching,transistor size is determinated.Biasing circuit is stabilized by ZTC of SiC and Si MOST.Results Circuit operating in 5V is simulated with Hspice.Varation of DC gain and P.M of SiC CMOS OPAMP is 2.5% and 3.3%,respectively.Howerver,gain of Si OPAMP drops from 64dB to-80dB,losing its temperature stability.Advantage of SiC material works under high temperature obviously.SiC devices suffer from some imperfect material properties,such as low channel mobility which will result the low transconductance from the circuit design point of view.Conclusion Circuit designed can be operated in high temperature,but single transistor of SiC is not better than counterpart of Si.
Multichip modules (MCM) allow many bare integrated circuit dies to be mounted onto the top layer, which provides an efficient solution to integration of microelectromechanical systems (MEMS) with microelectronics. The elimination of individual chip packages can significantly reduce inter-chip propagation delay and power consumption of the system. In this paper, new methods of packaging MEMS using advanced MCM foundry processes are described. A special purpose surface micromachined MEMS packaging test chip was designed and simulated. The MEMS test die was packaged with electronics die using the high density interconnect (HDI) technology and the Micro Modules System MCM-D process.
To improve two shortcomings of conventional network-on-chips, i.e. low utilization rate in channels between routers and excessive interconnection lines, this paper proposes a full asynchronous self-adaptive bi-directional transmission channel. It can utilize interconnection lines and register resources with high efficiency, and dynamically detect the data transmission state between routers through a direction regulator, which controls the sequencer to automatically adjust the transmission direction of the bi-directional channel, so as to provide a flexible data transmission environment. Null convention logic units are used to make the circuit quasi-delay insensitive and highly robust. The proposed bi-directional transmission channel is implemented based on SMIC 0.18 μm standard CMOS technology. Post-layout simulation results demonstrate that this self-adaptive bi-directional channel has better performance on throughput, transmission flexibility and channel bandwidth utilization compared to a conventional single direction channel. Moreover, the proposed channel can save interconnection lines up to 30% and can provide twice the bandwidth resources of a single direction transmission channel. The proposed channel can apply to an on-chip network which has limited resources of registers and interconnection lines.
A video capturing solution on embedded system is presented in this paper,including a video-capturing module connected to StrongARM SA-1110 platform and a driver under Windows CE.The OV7620 color digital CMOS image sensor is adopted in this module.At the same time,the slave mode of OV7620 is used to meet the demand of high integrity,low cost and low power dissipation on embedded system.
In order to reduce the high electric field peak near the gate edge and optimize the non-uniform surface electric field distribution of conventional AlGaN/GaN high electron mobility transistor (HEMT), a novel AlGaN/GaN HEMT with a partial GaN cap layer is proposed in this paper. The partial GaN cap layer is introduced at the top of the AlGaN barrier layer and is located from the gate to the drain drift region. A negative polarization charge at the upper hetero-junction interface is induced, owing to the polarization effect at the GaN cap layer and AlGaN barrier layer interface. Hence, the two dimensional electron gas (2DEG) density is reduced. The low-density 2DEG region near the gate edge is formed, which turns the uniform distribution into a gradient distribution. The concentration distribution of 2DEG is modified. Therefore, the surface electric field distribution of AlGaN/GaN HEMT is modulated. By the electric field modulation effect, a new electric field peak is produced and the high electric field peak near the gate edge of the drain side is effectively reduced. The surface electric field of AlGaN/GaN HEMT is more uniformly redistributed in the drift region. In virtue of ISE-TCAD simulation software, the equipotential and the surface electric field distribution of AlGaN/GaN HEMT are obtained. For the novel AlGaN/GaN HEMT employing a partial GaN cap layer, the 2DEG is completely depleted from the gate to the drain electrodes, arising from the low-density 2DEG near the gate edge, while the 2DEG is partly depleted for the conventional AlGaN/GaN HEMT. The surface electric field distribution of the conventional structure is compared with the one of the novel structures with partial GaN cap layers of different lengths at a fixed thickness of 228 nm. With increasing length, the new electric field peak increases and shifts toward the drain electrode, and the high electric field peak on the drain side of the gate edge is reduced. Moreover, the breakdown voltage dependence on the length and thickness of the partial GaN cap layer is achieved. The simulation results exhibit that the breakdown voltage can be improved to 960 V compared with 427 V of the conventional AlGaN/GaN HEMT under the optimum conditions. The threshold voltage of AlGaN/GaN HEMT remains unchanged. The maximum output current of AlGaN/GaN HEMT is reduced by 9.2% and the specific on-resistance is increased by 11% due to a 2DEG density reduction. The cut-off frequency keeps constant and the maximum oscillation frequency shows an improvement of 12% resulting from the increased output resistance. The results demonstrate that the proposed AlGaN/GaN HEMT is an attractive candidate in realizing the high-voltage operation of GaN-based power device.
This paper presents a high output-power step-down DC/DC converter based on the CSMC 0.5μm BCD(Bipolar-CMOS-DMOS) process.This chip provides a fast transient response and eases loop stabilization by using the current mode operation with the peak-current-control and slope compensation scheme.A power MOSFET with the conduct-resistor less than 0.18Ω is integrated in the chip,and it can provide an over 3.0A continuous output current.Simulation results and measurement show that the oscillating frequency is 400kHz,that the output power is more than 10W,and that the average efficiency is up to 85% over a wide supply range from 4.7V to 24V.The die area is less than 1.6mm×1.3mm,and the chip can be widely used in various distributed power systems.
As the multimedia technology evolves,compact disc plays a major role in the massive data storage media.Since the data acquisition speed is important in data retrieving system.The design and realization of a CMOS analog front-end proces-sor for up to48X speed CD retrieving system is presented in this paper.The front-end processor consists of a RF processor,an auto laser power controller and some detecting circuits.
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