臺灣博碩士論文加值系統

近年來因為CMOS製程的發展，跟隨而來的短通道效應已經改變了許多類比電路的設計，因為製程由深次微米朝向奈米技術發展，短通道效應變成了一個主要的設計課題。短通道效應影響轉導放大器的線性度效能越來越明顯，而電晶體飽和區的公式將會受到短通道效應的嚴重影響，因此許多由理想電流公式所衍伸出的傳統轉導放大器架構在先進的製程中所受到的非理想效應，比起過去製程將會更多。
本論文提出兩種以減少非理想的小信號電阻之方法提升線性度，用以補償短通道效應所產生之非線性諧波成分。此外，本論文將介紹轉導放大器的主要應用：轉導電容式濾波器。於論文最後，將介紹一個轉導電容式四階低通濾波器的設計過程與完成。
本文提出的第一個轉導放大器是基於源極退化架構的轉導放大器並以摺疊式翻轉電壓隨耦器及正回授的迴路增強其線性度。此轉導放大器以台積電0.18μm CMOS製程實現，其消耗功率3.7mW，工作電壓為1.8V。結果顯示當輸入信號為振幅為0.6Vpp且頻率10MHz時，達到第三次諧波失真為-70dB。此轉導放大器含接腳使用面積為0.5mm × 0.395mm。
本文提出的第二個轉導放大器是基於虛差動對輸入轉導放大器並以改進過的摺疊式翻轉電壓隨耦器增強其線性度。此轉導放大器以台積電0.18μm CMOS製程實現，其消耗功率0.7mW，工作電壓為1.8V。結果顯示當輸入信號為振幅為0.6Vpp且頻率10MHz時，達到第三次諧波失真為-78dB。此轉導放大器使用面積小於0.01 mm2。 使用此轉導放大器作為建構濾波器的區塊，製作一個頻率5Mhz的轉導電容式濾波器，此濾波器的諧波失真為-48dB，其消耗功率9.14mW，含接腳使用面積為0.502mm × 0.612mm。

In recent years, the short channel effect has changed the way of designing analog circuits, which becomes a main issue as the technology marches to deep-submicron fields. The impact of the short channel effect on the design of the operational transconductance amplifier (OTA) becomes more serious and makes the circuit performance deviated from the ideal voltage-current equation, especially the performance of the linearity.
This paper presents two fully balanced structures of CMOS Operational Transconductance Amplifier (OTA) with high linearity, and its applications to Gm-C filters. The transconductors are designed for highly linear applications using methods which reduce non-ideal small signal resistance.
The proposed first circuit based on the source-degeneration structure and enhanced with modified Folded Flipped Voltage Follower and positive feedback for linearity improving was designed by the TSMC 0.18μm CMOS technology and dissipates 3.7mW power with 1.8V voltage supply. The result shows the HD3 of -70dB with 0.6Vpp 10MHz input signal. It occupies the area of 0.5mm * 0.395mm, including pads.
The proposed second circuit based on the conventional pseudo-differential structure and enhanced with modified Folded Flipped Voltage Follower for linearity improving was designed by the TSMC 0.18μm CMOS technology and dissipates 0.7mW power with 1.8V voltage supply. The result shows the HD3 of -58dB with 0.6Vpp 10MHz input signal. The active area uses less than 0.01 mm2. Using this OTA as building blocks, a 5MHz Gm-C low-pass filter was designed with the HD3 of -48dB. It consumes 9.14mW and occupies the area of 0.502mm * 0.612mm, including pads.

Abstract in chinese I
Abstract in english III
Acknowledgement V
List of contents VI
List of figures VIII
List of tables X
Chapter 1 1
1.1 Motivation 1
1.2 Analog Filters 3
1.3 Thesis Overview 5
Chapter 2 6
2.1 Introduction 6
2.2 Basic transconductor structures 7
2.2.1 Differential input pair 7
2.2.2 Pseudo-differential input pair 9
2.3 Linearity improving techniques 11
2.3.1 Source Degeneration Differential Pair 12
2.3.2 Triode Transistor Input Pair 14
2.3.3 Flipped Voltage Followers 15
2.3.4 Folded Flipped Voltage Followers 16
2.3.5 Source Degeneration Differential Pairs with Positive Feedback 17
Chapter 3 19
3.1 Introduction 19
3.2 Proposed Operational Transconductance Amplifier with Linearity Enhanced
by Flipped Voltage Follower and Positive Feedback 20
3.2.1 Transconductor Gm stage 20
3.2.2 Programmable Current Mirror 22
3.2.3 Complete Transconductor Structure 24
3.2.4 Common-Mode Feedback 25
3.2.5 Noise Analysis 27
3.3 Proposed Tunable Pseudo-Differential Transconductor 28
3.3.1 Modified Flipped Voltage Follower 28
3.3.2 Complete Transconductor Structure 30
3.3.3 Common-Mode Feedback Circuit 32
3.3.4 Noise Analysis 33
Chapter 4 34
4.1 Introduction 34
4.2 Elementary Building Blocks for Gm-C filters 36
4.2.1 Resistors 36
4.2.2 Integrators 38
4.2.3 Gyrators 40
4.3 Fourth-order filter implementation 41
4.3.1 First order filter 41
4.3.2 Second-order section 42
4.3.3 Fourth-order filter 45
Chapter 5 47
5.1 Introduction 47
5.1.1 Total harmonic distortion (THD) 47
5.1.2 Common-mode rejection ratio (CMRR) 48
5.1.3 Power supply rejection ratio (PSRR) 49
5.1.4 Power 49
5.2 Performance of OTA with Linearity Enhanced by Flipped Voltage Follower
and Positive Feedback 50
5.2.1 Simulations 50
5.2.2 Layout and measurements 53
5.2.3 Performance summary 57
5.3 Performance of Tunable Pseudo-Differential Transconductor and fourth-order
filter 58
5.3.1 Simulations 59
5.3.2 Layout and measurements 63
5.3.3 Performance summary 72
Chapter 6 74
6.1 Conclusion 75
6.2 Future Works 75
Bibliography 76

[1] Sanchez-Sinencio, E. Silva-Martinez, J. , "CMOS transconductance amplifiers, architectures and active filters: a tutorial," Circuits, Devices and Systems, IEE Proceedings - , vol.147, no.1, pp.3-12, Feb 2000

[2] F. Krummenacher and N. Joehl, “A 4 Mhz CMOS continuous time filter with on-chip automatic tuning”, IEEE J. Solid-State Circuits, vol. 23, no. 3, pp. 750-758, Jun. 1988

[3] J. Silva-Martínez, J. Adut, M. Robinson, "A 60-mW 200-Mhz continuous-time seventh-order linear phase filter with on-chip automatic tuning system", IEEE J. Solid-State Circuit, vol. 38, no. 2, pp. 216-225, Feb. 2003

[4] C. C. Hung, K. A. Halonen, M. Ismail, “A Low-Voltage, Low-Power CMOS Fifth-Order Elliptic GM-C filter for Baseband Mobile, Wireless Communication,” IEEE Trans. Circuits Syst. Video Technol., vol. 7, pp. 584-593, Aug., 1997.

[5] J. A. De Lima and C. Dualibe, “A Linearly Tunable Low Voltage CMOS Transconductor With Improved Common-Mode Stability and Its Application to gm-C Filters,” IEEE Trans. Circuits Syst. II, vol, 48, no. 7, pp. 649–660, Jul. 2001.

[6] T. Y. Lo, C. C. Hung, and M. Ismail,“A Wide Tuning Range Gm-C Filter for Multi-Mode Direct-Conversion Wireless Receivers,” in Proc. IEEE ESSCIRC, Sep. 2007, pp. 210-213.

[7] S. Hori, T. Maeda, N. Matsuno, “Low-power Widely Tunable Gm-C Filter with an Adaptive DC-blocking, Triode-biased MOSFET Transconductor,” in Proc. ESSCIRC, 2004, pp. 99-102

[8] T.-Y. Lo and C.-C. Hung,”A 1-V 50MHz Pseudo-Differential OTA with Compensation of the Mobility Reduction,'' IEEE Transactions on Circuits and Systems II, vol. 54, no. 12, pp. 1047-1051, Dec. 2007.

[9] Bahmani, F. Sanchez-Sinencio, E,” A highly linear pseudo-differential transconductance,” Solid-State Circuits Conference, 2004. ESSCIRC 2004. Proceeding of the 30th European , pp. 111-114, 21-23 Sept. 2004.

[10] T.-Y. Lo and C.-C. Hung,”A 1-V 50MHz pseudo-differential OTA with compensation of the mobility reduction,'' IEEE Trans. Circuits Syst. II, vol. 54, no. 12, pp. 1047-1051, Dec. 2007.

[11] F. Bahmani; E. Sanchez-Sinencio,” A highly linear pseudo-differential transconductance,” in Proc. ESSCIRC, Sep. 2004. pp. 111-114.

[12] R. G. Carvajal, J. Ramirez-Angulo, A. J. Lopez-Martin, "The flipped voltage follower: a useful cell for low-voltage low-power circuit design," Circuits and Systems I: Regular Papers, IEEE Transactions on, vol. 52, pp. 1276-1291, 2005.

[13] B. Calvo, S. Celma, and M. T. Sanz, "A linear CMOS Gm-C-OTA biquad filter with 10-100 MHz tuning," in Circuits and Systems, 2004. MWSCAS '04. The 2004 47th Midwest Symposium on, 2004, pp. I-61-4 vol.1.

[14] R. Schaumann, S. M. Ghausi and K. R. Laker, Design of Analog Filters, Prentice-Hall, Englewood Cliffs, NJ, 1990, pp. 212-216

[15] S. Sawant, M. Ramirez-Angulo, J. Lopez-Martin, "Wide gm adjustment range highly linear OTA with programmable mirrors operating in triode mode,"Circuits and Systems, 2005. 48th Midwest Symposium on , vol., no., pp. 21- 23 Vol. 1, 7-10 Aug. 2005

[16] Padilla, I. Ramirez-Angulo, J. Carvajal, R.G., "Highly Linear V/I Converter with Programmable Current Mirrors," Circuits and Systems, 2007. ISCAS 2007. IEEE International Symposium on , vol., no., pp.941-944, 27-30 May 2007

[17] A.N. Mohieldin, E. Sanchez-Sinencio, J. Silva-Martinez, “ A fully balanced psudeo differential OTA with common-mode feedforward and inherent common-mode feedback detector”, IEEE, J. Solid-State Circuits, vol. 38, pp. 663-668, Apr. 2003.

[18] A.N.Mohieldin, E.Sánchez-Sinencio, and J.Silva-Martínez” Nonlinear Effects in Pseudo Differential OTAs With CMFB” IEEE Transactions on Circuits and Systems II, Analog and Digital Signal Processing, vol. 50, no. 10, Oct. 2003.

[19] C.L. Chien, C.C. Hung, C.W. Chen, "A pseudo-differential OTA with linearity improving by HD3 feedforward," Solid-State Circuits Conference, 2009. A-SSCC 2009. IEEE Asian , vol., no., pp.237-240, 16-18 Nov. 2009

[20] J. Galan, M. P. Carrasco, M. P. Pennisi, "Low-Voltage Tunable Pseudo- Differential Transconductor with High Linearity", ETRI journal, vol.31, no. 5, pp. 576, Oct. 2009

[21] C. C. Hung, K. A. Halonen, M. Ismail, “A Low-Voltage, Low-Power CMOS Fifth-Order Elliptic GM-C filter for Baseband Mobile, Wireless Communication,” IEEE Trans. Circuits Syst. Video Technol., vol. 7, pp. 584-593, Aug., 1997.

[22] T. Y. Lo, and C. C. Hung, “A 1 GHz OTA-Based Low-Pass Filter with A High-Speed Automatic Tuning Scheme,” IEEE Asian Solid-State Circuits conference (ASSCC), pp. 12-14, November 2007.

[23] T. Y. Lo, C. S. Kao, and C. C. Hung, “A Gm-C Continuous-time Analog Filter for IEEE 802.11 a/b/g/n Wireless LANs,” International Symposium on Signals, Circuits and Systems (ISSCS),vol. 1, pp. 1-4, July 2007.

[24] Galan, J.A. Gomez, Carrasco, “Pennisi, Melita, Low-Voltage Tunable Pseudo-Differential Transconductor with High Linearity, ” ETRI Journal. Vol. 31, no. 5, pp. 576-584. Oct. 2009

[25] Acosta, L. Carvajal, R.G. Jimenez, M. , "A CMOS transconductor with 90 dB SFDR and low sensitivity to mismatch," Circuits and Systems, 2006. ISCAS 2006. Proceedings. 2006 IEEE International Symposium on , vol., no., pp.4 pp.-72, 0-0 0

[26] Lujan-Martinez, C. Torralba, A. Carvajal, R.G. , "A −72 dB @ 2 MHz IM3 CMOS tunable pseudo-differential transconductor," Circuits and Systems, 2008. ISCAS 2008. IEEE International Symposium on , vol., no., pp.73-76, 18-21 May 2008

[27] Sato, H. Hyogo, A. Sekine, K. , "A low voltage OTA using MOSFET in the triode region and cascode current mirror," Circuit Theory and Design, 2005. Proceedings of the 2005 European Conference on , vol.3, no., pp. III/453- III/456 vol. 3, 28 Aug.-2 Sept. 2005

[28] Martinez-Heredia, J. Torralba, A. Carvajal, R.G. , "A new 1.5V linear transconductor with high output impedance in a large bandwidth," Circuits and Systems, 2003. ISCAS '03. Proceedings of the 2003 International Symposium on , vol.1, no., pp. I-157- I-160 vol.1, 25-28 May 2003

[29] I. S. Han, “A novel tunable transconductance amplifier based on voltage-controlled resistance by MOS transistors,” IEEE Trans. Circuits Syst. II, Exp. Briefs, vol. 53, no. 8, pp. 662–666, Aug. 2006.

[30] T. Sanchez-Rodriguez, C. I. Lujan-Martinez, R. G. Carvajal, “A CMOS linear tunable transconductor for continuous-time tunable Gm-C filters,” in IEEE ISCAS, May. 2008, pp. 912-915.