关于loop稳定性的的（开关电源）

siemens_skyeye

希望能给各位带来帮助谢谢。

wangxy001_hfut

hao dong xi a ,xiexie

sc266

thanks

vincentren

thanks for your share!

guojun1980

好资料！

gsy703

thanks

lmcon223

Thanks for your sharing!

lmcon223

Thanks for your sharing!

kkpman

xiexie 楼主

hi_china59

ANALOG BASEBAND CIRCUITS FOR WCDMA DIRECT-CONVERSION RECEIVERS

Tai-Cheng Lee* Chih-Pin Sun**
李泰成 孫致彬
應用於寬頻分工多重擷取系統直接降頻接收器的基頻類比電路
摘 要
直流電壓偏差在直接降頻接收機的設計中是一個嚴重的問題。因為一個小的電壓偏差會使基頻的放大器飽和而
減低雜訊比。傳統的直流偏壓消除是利用一個伺服迴路校正此偏差電壓，但是卻需要相當大的電容。本論文提出一個可應用於寬頻分工多重擷取系統的直接降頻接收機的直流偏壓消除技巧。利用修正伺服迴路和頻率相關負電阻，此直流偏壓消除電路只需要傳統電路四分之一的電容。本電路所用的製程是CMOS 0.18-μm。為了整合這樣的電路，在接收機中，一個基頻電路的濾波器也實現並和直流電壓消除電路整合。本電路電源消耗約6 mW，晶片大小約1.2mm2。
關鍵詞：直接降頻接收機、直流電壓偏差、電壓偏差消除、基頻電路。
Abstract
DC offset is one of the critical problems in directconversion receivers because a small DC offset can saturate the baseband amplifiers and degrades the signal-to-noise ratio. Conventional offset-cancellation techniques in direct-conversion receivers utilize a servo loop to null out DC offset voltage but need large on-chip capacitors. A DC-offset cancellation technique is proposed for WCDMA direct-conversion receivers. Employing a modified servo loop with frequency-dependent negative resistance (FDNR),
the DC-offset canceller can realize the required high-pass characteristics while using only less than quarters of on-chip capacitor compared with the method in [1]. The circuit is designed in a 0.18-μm CMOS technology and a baseband filter is integrated with the offset cancellation circuit. The overall power consumption is about 6 mW from a 1.8-V power supply and the chip area is 1.2 mm2. Keywords: direct-conversion receivers, DC offset, offset cancellation, baseband circuit. 1. INTRODUCTION Integrated wireless transceivers have drawn significant research interest in recent years. CMOS
technologies are widely used in these transceivers because of lower cost and smaller die area. Directconversion receivers are more attractive for monolithic integration since they require less hardware and suffer much less from mismatch-induced effects than conventional heterodyne architectures [2]. However, in direct-conversion architecture, it entails extraneous offset voltages for analog baseband circuits. The self-mixing of mixers and device mismatch generate DC offsets. Baseband amplifiers must provide most of the gain in a direct-conversion receiver, so a small DC offset at the input of the baseband of a receiver can saturate the baseband gain stages and degrade the sensitivity of the receiver, lowering the overall system SNR (signal-to-noise ratio).
Tai-Cheng Lee* Chih-Pin Sun**
李泰成 孫致彬