Performance Analysis of ZF and RZF in Low-Resolution ADC/DAC Massive MIMO Systems

Large number of antennas and higher bandwidth usage in massive multiple-input-multipleoutput(MIMO)systems create immense burden on receiver in terms of higher power consumption.The power consumption at the receiver radio frequency(RF)circuits can be significantly reduced by the application of analog-to-digital converter(ADC)of low resolution.In this paper we investigate bandwidth efficiency(BE)of massive MIMO with perfect channel state information(CSI)by applying low resolution ADCs with Rician fadings.We start our analysis by deriving the additive quantization noise model,which helps to understand the effects of ADC resolution on BE by keeping the power constraint at the receiver in radar.We also investigate deeply the effects of using higher bit rates and the number of BS antennas on bandwidth efficiency(BE)of the system.We emphasize that good bandwidth efficiency can be achieved by even using low resolution ADC by using regularized zero-forcing(RZF)combining algorithm.We also provide a generic analysis of energy efficiency(EE)with different options of bits by calculating the energy efficiencies(EE)using the achievable rates.We emphasize that satisfactory BE can be achieved by even using low-resolution ADC/DAC in massive MIMO.

Hardware for multi-superconducting qubit control and readout

We have developed an electronic hardware system for the control and readout of multi-superconducting qubit devices.The hardware system is based on the design ideas of good scalability,high synchronization and low latency.The system,housed inside a VPX-6U chassis,includes multiple arbitrary-waveform generator(AWG)channels,analog-digital-converter(ADC)channels as well as direct current source channels.The system can be used for the control and readout of up to twelve superconducting transmon qubits in one chassis,and control and readout of more and more qubit can be carried out by interconnecting the chassis.By using field programmable gate array(FPGA)processors,the system incorporates three features that are specifically useful for superconducting qubit research.Firstly,qubit signals can be processed using the on-board FPGA after being acquired by ADCs,significantly reducing data processing time and data amount for storage and transmission.Secondly,different output modes,such as direct output and sequential output modes,of AWG can be implemented with pre-encoded FPGA.Thirdly,with data acquisition ADCs and control AWGs jointly controlled by the same FPGA,the feedback latency can be reduced,and in our test a 178.4 ns latency time is realized.This is very useful for future quantum feedback experiments.Finally,we demonstrate the functionality of the system by applying the system to the control and readout of a 10 qubit superconducting quantum processor.

Extracavity Parametric Oscillation with Continuous and/or Discontinuous Frequency Tuning

A continuously or/and discontinuously tunable LiNbO3 Optical Parametric Oscillator (OPO) with the spectral range of 1.42 - 4.24 um and shifting of 0…12 nm is created and investigated. The OPO resonator ring circuit provides for the radiation energy output value of up to 50 mJ. Radiation bandwidth narrowing of up to 0.7 cm–1 by introducing of the Fabry-Perot etalon into the OPO resonator has been obtained.

A 3V 5.88mW 13b 400kHz Sigma-Delta Modulator with 84dB Dynamic Range

This paper introduces a high-revolution,200kHz signal bandwidth EA modulator for low-IF GSM receivers that adopts a 2-1 cascaded single-bit structure to achieve high linearity and stability. Our design is realized in a standard 0.18μm CMOS process with art active area of 0.5mm× 1.1mm.The EA modulator is driven by a single 19.2MHz clock signal and dissipates 5.88mW from 3V power supply. The experimental results show that,with an oversampling ratio of 48, the modulator achieves a 84.4dB dynamic range,73.8dB peak SNDR, and 80dB peak SNR in the signal bandwidth of 200kHz.