摘要：全球移动通信系统（GSM）与通用移动电信系统（UMTS）手机网络的长期演进（LTE）要求无线通信网络实现重大模式转型——从电路交换语音网络向全数据包（IP）网络过渡。随着所有服务都能通过包化数据得到支持，网络电话（VOIP）也将用于支持语音流量。LTE的目标，

摘要：In present work, improved designs for voltage controlled ring oscillators (VCO) using three transistors XNOR/XOR gates have been presented. Supply voltage has been varied from [1.8 - 1.2] V in proposed designs. In first method, the VCO design using three XNOR delay cells shows frequency variation of [1.900 - 0.964] GHz with [279.429 - 16.515] μW power consumption variation. VCO designed with five XNOR delay cells shows frequency variation of [1.152 - 0.575] GHz with varying power consumption of [465.715 - 27.526] μW. In the second method VCO having three XOR stages shows frequency variation [1.9176 - 1.029] GHz with power consumption variation from [296.393 - 19.051] μW. A five stage XOR based VCO design shows frequency variation [1.049 - 0.565] GHz with power consumption variation from [493.989 - 31.753] μW. Simulations have been performed by using SPICE based on TSMC 0.18μm CMOS technology. Power consumption and output frequency range of proposed VCOs have been compared with earlier reported circuits and proposed circuit’s shows improved performance.

摘要：Digital controlled oscillators（DCOs） are the core of all digital phase locked loop（ADPLL） circuits. Here,DCO structures with reduced hardware and power consumption having full digital control have been proposed. Three different DCO architectures have been proposed based on ring based ***,four and five bit controlled DCO with NMOS,PMOS and NMOS PMOS transistor switching networks are presented.A three-transistor XNOR gate has been used as the inverter which is used as the delay *** has been controlled digitally with a switch network of NMOS and PMOS *** three bit DCO with one NMOS network shows frequency variations of 1.6141-1.8790 GHz with power consumption variations 251.9224-276.8591μW. The four bit DCO with one NMOS network shows frequency variation of 1.6229-1.8868 GHz with varying power consumption of 251.9225-278.0740μW.A six bit DCO with one NMOS switching network gave an output frequency of 1.7237-1.8962 GHz with power consumption of 251.928-278.998μ*** frequency and power consumption results for 4 6 bit DCO circuits with one PMOS and NMOS PMOS switching network have also been *** phase noise parameter with an offset frequency of 1 MHz has also been reported for the proposed *** with earlier reported circuits have been made and the present approach shows advantages over previous circuits.

摘要：The goal of this paper is to design and develop low conversion loss mixers at Ku Band (12 - 18 GHz) in microstrip line configuration. The Ku-band (Kurtz-under band) is primarily used for satellite Communications, particularly for editing and broadcasting satellite television. CAD tools (Agilent’s Advance Design System software) have been used for simulation and optimization of the circuits. 180 degree balanced mixer configuration has been adopted due to better RF to LO isolation requirement. The circuit is designed on microstrip line using RT Duroid (Dielectric Constant = 2.22). Initially a rat race coupler (180 degree hybrid) was designed and simulated and optimized for required performance successfully.