*收稿日期:
2013-11-29
基金项目:国家杰出青年科学基金资助项目(50925727);国家自然科学基金资助项目(60876022,61201108);国防科技计划
项目(C1120110004,9140A27020211DZ5102);湖南省科技计划项目(2011JK2023,2013GK3096)
作者简介:童耀南(1977- ),男,湖南平江人,湖南大学博士研究生,湖南理工学院讲师
通信联系人:E-mail:yaontong@hnu.edu.cn
Morlet
复小波变换的开关电流电路共极点实现
*
童耀南
1,3
,
何怡刚
1,2
,
尹柏强
1
,
于文新
1
,
龙英
2
(1.
湖南大学电气与信息工程学院
,
长沙
410082;
2.
合肥工业大学电气与自动化学院
,
合肥
230009;
3.
湖南理工学院信息与通信工程学院
,
岳阳
414006 )
摘
要
:
提出了一种时频域混合共极点逼近的开关电流电路
Morlet
复小波变换方法
.
将
Morlet
复小波构成部件高斯包络进行
分解
,
设计了高斯包络时域逼近优化模型
,
模型可采用常规优化算法求解
.
利用正弦和余弦信号的周期性
,
及其与指数信号的乘积在
频率域具有相同极点的特性
,
简化了
Morlet
复小波函数的拉普拉斯变换
,
实现了实部和虚部的共极点有理逼近
.
基于双线性变换积
分器设计了一种开关电流复二阶节基本电路
,
继而综合了
Morlet
复小波变换基本电路
.
通过调节基本电路的开关时钟频率可实现其
它不同尺度的小波变换功能
.
对比分析表明
,
本文方法的逼近效果和系统稳定性均明显优于现有的
Pad
é变换法和
Maclaurin
级数
法;与现有方法相比,本文设计的复小波变换电路具有结构简单、功耗低和体积小等优点
.
仿真结果表明了方法的有效性
.
关键词
:
开关电流电路
; Morlet
复小波变换
;
小波滤波器
;
共极点逼近
中图分类号
:
TN713
文献标识码
:
A
Poles-shared Realization of Morlet Complex Wavelet Transform Using
Switched-current Circuits
TONG Yao-nan
1,3
, HE Yi-gang
1,2
, YIN Bai-qiang
1
, YU Wen-xin
1
, LONG Ying
2
(1.School of Electrical and Information Engineering, Hunan University, Changsha 410082, China;
2. School of Electrical Engineering and Automation, Hefei University of Technology, Hefei 230009, China;
3. School of Information and Communication Engineering, Hunan Institute of Science and Technology, Yueyang 414006, China)
Abstract: A new scheme of implementing Morlet complex wavelet transform using poles-shared Switched-current (SI) circuits
was proposed. In which a hybrid method in time and frequency domain was presented for approximation of Morlet complex wavelet.
By decomposing the Gaussian envelop, which is a component of the Morlet complex wavelet, an approximation optimization model in
time domain was designed. It can be solved in universal optimization algorithms. By using the periodic characteristics of the sine and
cosine signals, the Laplace transforms of the approximated Morlet complex wavelet can be simplified. What is more, the rational real
and image parts of the approximated Morlet complex wavelet have shared poles because of that the product of sine and exponential
and that of cosine and exponential have same poles in s-domain. A kind of SI complex second order section circuit was designed based
on the bilinear z-transform integrator module. Then it was used to synthesize the Morlet complex wavelet base circuit. By adjusting the
circuit’s switch clock frequency, the wavelet transform in other scales can be realized. The comparative analysis demonstrated that the
proposed approximation method is better than the Padé transform and Maclaurin series method in accuracy and stability. Furthermore,
the circuit designed in this paper has the advantages of more simple structure, lower power consumptions and smaller volumes
compared with the existing method. Simulation results verified the effectiveness of the proposed scheme.
Keywords: switched-current circuits; Morlet complex wavelet transform; wavelet filters; poles-shared approximation
小波变换是分析非平稳信号强有力的工具
,
已有
广泛的工程应用
[1,2]
.
小波变换通常采用数字方式实现
,
但其运算量大
,
且需要进行模数转换
,
不适合功耗要求
严格的应用场合
.
近年来
,
为满足实时性和低功耗场合
的要求
,
人们开始致力于小波变换模拟电路实现的研
究
[3-13]
.
其中文献
[3]
提出了基于开关电容电路的连续
小波变换方法
,
但开关电容是一种电压模技术
,
需要线
性浮置电容
,
与标准数字
CMOS
工艺不兼容
.
为克服开
关电容的缺陷
,
开关电流技术
[14,15]
应运而生
.
开关电流
是一种新型的模拟电流数据采样技术
,
具有高速度、
低电压、低功耗的优点
.
文献
[4,5]
最早提出开关电流电
路实现小波变换的理论与方法
.
开关电流小波变换电