مطالعه zero-if مخلوط کننده ی متوازن مضاعف برای گیرنده های وایمکس
Abstract
1- Introduction
2- Background
3- Methodology
4- Results and discussion
5- Conclusions
References
Abstract
Differential approach is becoming highly preferred in radio frequency integrated circuit (RFIC) design due to its advantages, particularly its high immunity to common-mode noises, satisfactory rejection of parasitic coupling, and increased dynamic range. One particular RF front-end building block that is often designed as differential circuit is the mixer. This paper presents a study and design of a differential mixer, particularly the double-balanced mixer implemented on a zero-IF (zero-intermediate frequency) or direct-conversion architecture in a standard 90 nm complementary metal-oxide semiconductor (CMOS) process operating at frequency of 5 GHz, which is a typical frequency for worldwide interoperability for microwave access (WiMAX) receiver. Impedance matching was necessary to fully optimize the mixer design. The zero-IF double-balanced mixer design achieved conversion gain of 11.46 dB and noise figure of 16.53 dB, comparable to other mixer designs.
Introduction
Receiver front-end of a radio frequency (RF) system is of particular interest to many integrated circuit (IC) designers and researchers as it proves to be the most critical part in many communication systems and wireless applications such as wireless fidelity (WiFi), bluetooth, longterm evolution (LTE), and worldwide interoperability for microwave access (WiMAX). The block diagram of a typical receiver is shown in Fig. 1. Mixer is one of the key front-end building blocks in an RF receiver. It is also called a converter because it converts RF signals into a lower intermediate frequency (IF) by mixing with an offset local oscillator (LO). Depending on the receiver requirements, mixers must undergo a careful design process since a lot of tradeoffs among different performance parameters must be considered and understood. Ultimately, the objective is to study and design a zero-IF double-balanced mixer implemented in a standard 90 nm complementary metal-oxide semiconductor (CMOS) process. Operating frequency is set to 5 GHz, which is a typical frequency for a WiMAX receiver.