Design of Low-Voltage Cmos Switched-Opamp Switched-Capacitor Systems

by Cheung, Vincent S. L.; Luong, Howard Cam

• ISBN13: 9781402074660
• ISBN10: 1402074662
• Format: Hardcover
• Copyright: 2003-07-01
• Publisher: Kluwer Academic Pub

Summary

Demand for low-power low-voltage integrated circuits (ICs) has rapidly grown due to the increasing importance of portable equipment in all market segments including telecommunications, computers, and consumer electronics. The need for low-voltage ICs is further motivated by CMOS technology scaling that requires low supply voltages for device reliability. On the other hand, switched-capacitor (SC) circuits, which have been well known for high accuracy and low distortion, have also become increasingly attractive for low-voltage, low-power, and even high-frequency applications. Switched-opamp (SO) technique has been proposed to enable SC circuits to operate with a single 1-V supply in standard CMOS processes without any clock voltage multiplier or low-threshold devices. However, the existing SO technique requires the opamps to turn off after their integrating phases and thus is not suitable for most of the switched-capacitor systems. In Design of Low-Voltage CMOS Switched-Opamp Switched-Capacitor Systems , the emphasis is put on the design and development of advanced switched-opamp architectures and techniques for low-voltage low-power switched-capacitor (SC) systems. Specifically, the book presents a novel multi-phase switched-opamp technique together with new system architectures that are critical in improving significantly the performance of switched-capacitor systems at low supply voltages: *A generic fast-settling double-sampling SC biquadratic filter architecture is proposed to achieve high-speed operation for SC circuits. *A low-voltage double-sampling (DS) finite-gain-compensation (FGC) technique is employed to realize high-resolution SD modulator using only low-DC-gain opamps to maximize the speed and to reduce power dissipation. *A family of novel power-efficient SC filters and SD modulators are built based on using only half-delay SC integrators. *Single-opamp-based SC systems are designed for ultra-low-power applications. In addition, on the circuit level, a fast-switching methodology is proposed for the design of the switchable opamps to achieve switching frequency up to 50 MHz at 1V, which is improved by about ten times compared to the prior arts. Finally, detailed design considerations, architecture choices, and circuit implementation of five chip prototypes are presented to illustrate potential applications of the proposed multi-phase switched-opamp technique to tackle with and to achieve different stringent design corners such as high-speed, high-integration-level and ultra-low-power consumption at supply voltages of 1V or lower in standard CMOS processes.

Table of Contents

Table of Contents	i
List of Figures	v
List of Tables	xi
Preface	xiii
Acknowledgement	xv
Introduction	1	(6)
Situations of Research	1	(3)
Research Objectives	4	(1)
Outline of this Book	4	(3)
Analysis and Design Considerations of Switched-Opamp Techniques	7	(32)
Introduction	7	(1)
Minimum Supply Voltage for SC Circuits	8	(1)
Low-Voltage Solutions for SC Circuits	9	(1)
Original Switched-Opamp Technique	10	(2)
Multi-Phase Switched-Opamp Technique	12	(4)
Analysis of Parasitic-Sensitive Switched-Capacitor and Switched-Opamp Integrators	16	(19)
Analysis of Conventional Parasitic-Insensitive SC Integrators	16	(4)
Analysis of Conventional Parasitic-Insensitive Integrators Using Original Switched-Opamp Technique	20	(6)
Analysis of Conventional Parasitic-Insensitive Integrators Using Multi-Phase Switched-Opamp Technique	26	(9)
Performance Comparisons of Switched-Capacitor and Switched-Opamp Integrators	35	(3)
Conclusion	38	(1)
System Considerations for Switched-Opamp Circuits	39	(24)
Introduction	39	(1)
Principle of the Double-Sampling Technique	40	(2)
Settling Problems of Opamps in Conventional Double-Sampling SC Architecture	42	(1)
Proposed Fast-Settling Double-Sampled Generic SC Biquadratic Filter	43	(2)
Proposed Half-Delay-SC-Integrator-Based Generic SC Biquadratic Filter	45	(5)
Proposed Half-Delay-SC-Integrator-Based SC Ladder Filter	50	(4)
Proposed Half-Delay-SC-Integrator-Based SC Lowpass ΣΔ Modulator with Noise-Shaping Extension	54	(7)
Conclusion	61	(2)
Circuit Implementation and Layout Considerations for Switched-Opamp Circuits	63	(12)
Introduction	63	(1)
Opamp Design Considerations for Switched-Opamp Circuits	63	(3)
Design Review of Switchable Opamps	66	(3)
Design of Switchable Opamp by Switching Bias Current	66	(1)
Design of Switchable Opamp by Disconnecting from Power Rails	67	(1)
Design of Switchable Opamp by Switching Output Stage	68	(1)
A Proposed Fast-Switching Methodology for the Design of Switchable Opamp	69	(1)
Layout Considerations for Switched-Capacitor Systems	70	(4)
Layout Floorplan for Switched-Capacitor Circuits	70	(1)
Layout Technique for Matching Capacitors	71	(1)
Layout Considerations for Minimizing Switching Noise Effect	72	(1)
Layout Considerations for Minimizing Parasitic Capacitive Loading to Opamp	73	(1)
Conclusion	74	(1)
Design of a Switched-Capacitor Pseudo-2-Path Filter Using Multi-Phase Switched-Opamp Technique	75	(20)
Introduction	75	(1)
N-Path and Pseudo-N-Path Filters	76	(4)
N-Path Filter	76	(3)
Pseudo-N-Path Filter	79	(1)
Z to ZN Transformation Using RAM-Type SC Pseudo-N-Path Integrator	80	(2)
Design of a 1-V Switched-Opamp SC Pseudo-2-Path Filter	82	(3)
Circuit Implementation	85	(2)
Experimental Results	87	(7)
Conclusion	94	(1)
Design of Low-Power and High-Frequency Switched-Opamp Circuits	95	(22)
Introduction	95	(1)
Bandpass ΣΔ Modulator Topology	96	(1)
Fast-Settling Double-Sampled SC Resonator	97	(1)
1-V Double-Sampling Finite-Gain-Compensation Technique	98	(4)
Realization of DSFGC Bandpass ΣΔ Modulator	102	(2)
Design of Low-Voltage Building Blocks	104	(7)
Current-Mirror Operational Amplifier	104	(2)
1-V Switchable Current-Mirror Opamp with Dual Time-Multiplexed Output Stages	106	(2)
Current-Injected Common-Mode Feedback Circuit	108	(1)
1-V Latch-Type Comparator	109	(1)
1-V D-Flip-Flop	110	(1)
Experimental Results	111	(5)
Conclusion	116	(1)
Design of Low-Power and High-Level Integrated Switched-Opamp Circuits	117	(18)
Introduction	117	(1)
System Description	118	(2)
Design of 1-V Switched-Opamp Biquadratic Filter	120	(1)
Design of 1-V Switched-Opamp Ladder Filter	121	(2)
Design of 1-V Switched-Opamp Lowpass ΣΔ Modulator with Noise-Shaping Extension	123	(1)
Quadrature Channels Optimization	124	(2)
Circuits Implementation	126	(1)
Experimental Results	127	(7)
Conclusion	134	(1)
Design of Ultra-Low-Power Single-Switched-Opamp-Based Systems	135	(30)
Introduction	135	(1)
System Considerations	136	(1)
Design of a 0.9-V Sub-μW SC ΣΔ Modulator	137	(12)
Single-Opamp-Based ΣΔ Modulator Topology	138	(1)
Switchable Opamp Design	139	(1)
Dynamic Common-Mode Feedback Circuit	140	(1)
1-V Latch-Type Comparator	141	(1)
Experimental Results of the SSOP ΣΔ Modulator	142	(7)
Design of a 0.9-V Sub-μW SC Signal Conditioning System	149	(14)
Single-Switched-Opamp-Based Realization	151	(4)
Switchable Opamp Design	155	(1)
Dynamic Common-Mode Feedback Circuit	156	(1)
Experimental Results of the SC Signal Conditioning System	157	(6)
Conclusion	163	(2)
Conclusion	165	(2)
Appendix A: Procedures of Performing Time Domain Analysis of SC Circuits	167	(2)
Appendix B: Analysis of Finite-Opamp-Gain Effects on Inverting SC Integrators	169	(6)
Appendix C: Design Procedures of SC Biquadratic Filter	175	(2)
Appendix D: Design Procedures of SC Ladder Filter	177	(4)
References	181	(8)
Index	189