本論文提出一個on-chip自動調諧電路，此電路為3.3伏特截止頻率為1.1MHz的巴特渥茲低通轉導電容濾波器可應用在ADSL。我們提出一個新的調整方法來調整濾波器的截止頻率，此頻率調整電路可以減低因為製程變異所造成的截止頻率的誤差，而且不需要一個off-chip的大電容。我們經由HSPICE模擬並使用TSMC 0.35um ， 2P4M CMOS的製程技來驗證電路的可行性。

An on-chip automatic tuning circuit is proposed. The circuit is applied to a 3.3V 1.1MHz butterworth low-pass Gm-C filter for ADSL (Asymmetric Digital Subscriber Loops). A new frequency tuning method is used to adjust the cut-off frequency of the filter. The frequency tuning circuit can reduce the tolerance due to process variations and without a large off-chip capacitor. HSPICE simulations and experimental results verify the proposed circuits. All the circuits are designed based on the TSMC 0.35um 2p4m CMOS process technology.

Chapter 1 Introduction 1

1.1 Motivation 1
1.2 Thesis Organization 3

Chapter 2 Previous The OTA and Frequency 4
Tuning Circuit

2.1 The OTA Circuit 4
2.1.1 OTA Circuit with Triode Transistors 5
2.2 The Automatic Frequency Controller 6
2.2.1 Frequency Tuning Circuit 7
2.2.2 Switched-Capacitor Frequency Tuning 9

Chapter 3 Design of the OTA, Frequency Tuning 11
Circuit and its Application in Filter

3.1 Design of the OTA 11
3.1.1 Design of the Full Differential OTA 12
3.1.2 The Common-mode Feedback Circuit 15
3.2 The Proposed Frequency Tuning Circuit 18
3.2.1 Basics of the Proposed Frequency 19
Tuning Circuit
3.3 Design of the 1.1MHz 4th-Order Butterworth 22
Low-pass Filter
3.3.1 Basic Filter Theorem 22
3.3.2 The Biquad 23
3.3.3 The Butterworth Lowpass Filter 26

Chapter 4 Simulation and Experimental Results 28

4.1 The OTA Simulation Results 28
4.2 The Filter Simulation Results 31
4.2.1 Simulation Results of the 1.1-MHz 31
4th-Order Butterworth Lowpass Filter
without Frequency Tuning Circuit
4.2.2 Simulation Results of the 1.1-MHz 32
4th-Order Butterworth Lowpass Filter
with Frequency Tuning Circuit
4.3 Experimental Results and Layout 34

Chapter 5 Conclusions 38

Reference 39

[1] R. Jacob Baker, Harry W. Li and David E. Boyce,” CMOS Circuit Design, Layout, and Simulation ”, pp.755-760.
[2] Poberezhskiy, Y.; Poberezhskiy, G.,” Sample-and-hold amplifiers performing internal antialiasing filtering and their applications in digital receivers “, IEEE Circuits and Systems, 2000, vol.3, pp.439-442.
[3] Jiunn-Yih Lee, Chien-Cheng Tu, Wei-Hong Chen,”A 3 V linear input range tunable CMOS transconductor and its application to a 3.3 V 1.1 MHz Chebyshev low-pass Gm-C filter for ADSL”, IEEE CICC 2000, 21-24 May 2000, pp.387-pp.390.
[4] Mehrmanesh, S.; Atarodi, M.;” A high dynamic range CMOS variable gain filter for ADSL”, ISCAS 2002, Volume 4, 26-29 May 2002, pp.IV-257 - IV-260.
[5] Ibaragi, E.; Hyogo, A.; Sekine, K.,” A 1-MHz 7th-order continuous-time lowpass filter using very low distortion CMOS OTAs ”, 2000, IEEE Circuits and Systems, vol.2, pp.569-572.
[6] David Johns; Ken Martin, ”Analog Integrated Circuit Design”, John Wiley & Sons on Canada, 1997, pp.628.
[7] David Johns; Ken Martin, ”Analog Integrated Circuit Design”, John Wiley & Sons on Canada, 1997, pp.631.
[8] David Johns; Ken Martin, ”Analog Integrated Circuit Design”, John Wiley & Sons on Canada, 1997, pp.629.
[9] Rolf Schaumann, Mac E. Van Valkenburg, “ Design of Analog filters “, New York Oxford, 2001, pp.660-662.
[10] David Johns; Ken Martin, ”Analog Integrated Circuit Design”, John Wiley & Sons on Canada, 1997, pp.631.
[11] Voghell, J.-C.; Sawan, M, “Current tuneable CMOS transconductor for filtering applications”, ISCAS 2000, Volume 5, 28-31, pp.165 – 168.
[12] Rolf Schaumann, Mac E. Van Valkenburg, “ Design of Analog filters “, New York Oxford, 2001, pp.6-8.
[13] Rolf Schaumann, Mac E. Van Valkenburg, “ Design of Analog filters “, New York Oxford, 2001, pp.613-614.
[14] Rolf Schaumann, Mac E. Van Valkenburg, “ Design of Analog filters “, New York Oxford, 2001, pp.624-625.
[15] Rolf Schaumann, Mac E. Van Valkenburg, “ Design of Analog filters “, New York Oxford, 2001, pp.630-632.
[16] Rolf Schaumann, Mac E. Van Valkenburg, “ Design of Analog filters “, New York Oxford, 2001, pp.256-258.