一种双波段MEMS低噪声放大器设计

本文利用一种MEMS电容式开关并联实现双波段2．1GHz／4．6GHz微机械低噪声放大器。根据MEMS电容开关的电容特性，实现LNA电路匹配阻抗的变化、在不同的波段实现谐振匹配，从而实现双波段分别放大的功能。首先提出一种电容式开关的设计，理论、仿真分析了开关的特性，开关在2．21GHz和4．8GHz具有良好的插入损耗和隔离度、插损为2．2dB左右，隔离度达到30dB以上。其次将开关引入于基于Casoode放大管的LNA电路中、和CMOS电路具有很好的兼容性，设计了LNA的电路模型和仿真分析、分析结果表明，在频率为2．21GHz时、增益达到11．4dB，4．8GHz时、增益达12．5dB，二波段隔离度在30dB以上、噪声在4．1dB左右，该研究方法和设计克服了普通双波段LNA需要两路单独电路的缺点，该器件可应用在Wimax，WiFi等3．5G、4G无移动通信网络中。

A novel dual-band MEMS LNA design

Dual- band LNA （Lower noise amplifier） is studied, and it is composed of the series MEMS capacity switch, cascode amplifier and other circuit, and gets the dual- band of 2.1GHz/4.6GHz LNA by the switch capacity variation. The first, a MEMS （Micro- Electric- Machine- Systems）capacity switch is designed, analysis the switch by EDA of HFSS, and obtain the insert loss and isolation with 2.1GHz and 4.6GHz, insert loss is about 2.2dB and isolation is about 30dB.The second, the MEMS switch is applied in the LNA circuit, and the circuit model is designed basing on the CMOS technology. The performance is obtained by test equipment, and the gain is 1.4dB and 12.5dB with 2.21GHz and 4.8GHz, dual - band noise coefficient is about 4. ldB,and isolation is about 30dB. It has good performance and applied for the 3.5G（Generation） ,4G mobile commnications, such as Wimax, Wifi systems.