本論文提出一個使用pseudo-exponential方程式與飽和區操作金氧半電晶體的CMOS可調式二階對數領域濾波器。與雙載子電晶體BJT或弱轉換金氧半電晶體濾波器相比，擁有較高的工作頻率。

在本研究中使用 0.35um CMOS 製程製作晶片，供應電壓為3V，內建電容為1pF，調整電流為2uA~10uA，截止頻率為2MHz~37.5MHz，總諧波失真為0.93%，功率損耗為772uW。

In this thesis, a CMOS tunable second-order log-domain filter using pseudo-exponential approximation is proposed. MOSFETs in the circuit are working in the saturation region. This filter has higher frequency response than that of weak inversion CMOS filter.

The circuit has been fabricated with 0.35um CMOS technology. It operates with a supply voltage 3V, internal capacitance C is 1pF, the biasing current varies from 2uA~10uA. The cutoff frequency can be turned from 2MHz~37.5MHz. The harmonic distortion is 0.93% and the power consumption is 772uW.

Abstract

Chapter 1 Introduction 1
1.1 Background 1
1.2 Companding Filter 2
1.3 Motivation 4
1.4 Thesis Organization 5

Chapter 2 Previous Log Filter 6
2.1 Adams’s Log Filter Circuit 6
2.2 BJT Log-Domain Filter 9
2.3 Lateral Bipolar Transistor Log-Domain Filter For CMOS 11
2.4 CMOS Weak Inversion Log-Domain Filter 13
2.5 SRD filter 16
2.6 The Pseudo-Exponential Filter 18
2.6.1 Positive Transconductor 18
2.6.2 Negative Transconductor 20
2.6.3 The First-Order Filter 21
2.6.4 The Second-Order Filter 23

Chapter 3 The Proposed Circuit 25
3.1 Positive Transconductance 25
3.2 Negative Transconductance 26
3.3 The Proposed Second-Order Log-domain Filter 27
3.3.1 Input Circuit 29
3.3.2 Output Circuit 31
3.4 Transfer Function 32

Chapter 4 Simulation and Measurement Results of the Proposed
Second-Order Log Filter 36
4.1 The Circuit Implement, Layout& Specifics 36
4.2 Testing method & Measurement circuit 39
4.3 Frequency Response 40
4.4 Time response 42
4.5 Tunable Range 45
4.6 Total Harmonic Distortion 46
4.7 Comparisons 47

Chapter 5 Conclusion 49

References 50

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