Shu-Chuan Huang

A wide range differential difference amplifier: a basic block for analog signal processing in MOS technology

A CMOS implementation of a wide-input-range differential difference amplifier (DDA) using a V-I converter with large signal handling capability is presented. The DDA is used as a basic building block for continuous-time analog signal processing systems. The basic features of the DDA are verified experimentally using a 2- mu m CMOS process MOSIS chip. It is shown that it is generally possible to develop DDA-based analog circuitssth almost infinite input impedances, low component count and without the need to match components/devices external to the DDA. DDA-based circuits such as amplifiers, a MOS grounded resistor, four quadrant multipliers and amplitude modulators are presented. Applications of the DDA in the implementation of frequency selective circuits, e.g., resonator and state-variable second-order filters, are also given. All proposed circuits and design techniques are experimentally verified and demonstrate that DDA-based circuits offer a competitive alternative to op-amp-based circuits. >

CMOS multiplier design using the differential difference amplifier

This paper presents design techniques for a wide range CMOS differential difference amplifier (DDA) and discusses its application as a basic block in the implementation of four-quadrant multipliers and amplitude modulators, which are widely used in analog signal processing. The DDA can be reconfigured as an op amp, and makes use of the op amp-based multipliers, which are well-developed. In addition, it can be shown that the DDA can be implemented as an AM circuit using only a transistor and a resistor. Experimental results obtained from a 2 /spl mu/m CMOS MOSIS chip are given.<<ETX>>

Design and applications of a CMOS analog multiplier cell using the differential difference amplifier

This paper presents design techniques for a wide input range CMOS differential difference amplifier (DDA) and discusses its application as a basic block in the implementation of a simple four-quadrant multiplier cell. The cell can be configured as an amplitude modulator or a one-over circuit, which are widely used in many analog signal processing applications. The DDA can also be reconfigured as an opamp, and hence can be used to design many of the opamp-based multiplier circuits. The DDA amplitude modulator (AM) uses a transistor and a resistor as the only components external to the DDA. A DDA one-over circuit, which provides an output proportional to the inverse of the input, is also achieved with the same level of simplicity. High-frequency effects due to the DDAs finite gain-bandwidth (GB) and MOS parasitic capacitances are investigated. Experimental results obtained from a 2µm CMOS MOSIS chip are given.

Design of low-voltage linear tunable CMOS V-I converters with a rail-to-rail input range

The design techniques of low-voltage V-I converters are discussed. It is shown that the input operating range of two conventional linear V-I converters is able to extend to rail-to-rail with the use of extra complementary stages similar to those employed in the inputs of low-voltage opamps. The THD (total harmonic distortion), simulated with 0.8 /spl mu/m HSPICE level 6 models, shows less than 1% throughout the entire operating range (/spl plusmn/1.5 V).

Design of a CMOS differential difference amplifier and its applications in A/D and D/A converters

The differential difference amplifier (DDA) is an extension of an opamp with two differential inputs. DDA-based circuits often provide high input impedance and simple external circuitry due to the feature of differential difference inputs. Therefore, DDA-based circuits are competitive alternatives to opamp-based circuits. In this paper, we will present the design of a DDA using a proposed linear V-I converter whose linearity is improved by the body effect. This DDA possesses almost rail-to-rail input common-mode range and output swing and is therefore suitable for low-voltage applications. The DDA was fabricated in a MOSIS 2 /spl mu/m p-well process, and its simulation and experimental results are provided. Applications in A/D and D/A converters are discussed.

Synthesis of QDI FSMs from Synchronous Specifications

Quasi-Delay insensitive (QDI) circuits are the most robust and practical that can be built and are resilient to process, temperature and voltage (PVT) variations. Although there are many research papers that can translate synchronous designs into asynchronous sequential designs, to the best of our knowledge, there is neither QDI finite state machine (FSM) models proposed nor algorithms or tools designed. Three QDI FSM (QFSM) designs (i.e. NCLD, NCLX and ROC QFSMs) are proposed and an algorithm to automatically synthesize QFSMs from synchronous FSM specifications in Verilog is designed and implemented in Java. One of the distinguish feature is that the behaviors of our QFSMs are the same as those of the corresponding synchronous FSMs in terms of functionality. This greatly simplifies the verification complexity and reduces verification cost. Two sets of FSM circuits (i.e. verifiable benchmark circuits and ISCAS89) are exploited to carry out verification and performance evaluation. The experimental results show that ROCopt QFSMs use the least hardware cost and consume lowest energy in average.

Performance verification of start-up circuits in reference generators

A new approach for identifying the number of stable equilibrium points in supply-insensitive bias generators, references, and temperature sensors based upon self-stabilized feedback loops is introduced. This provides a simple and practical method for determining if these circuits require a “start-up” circuit and, if needed, for verifying that the startup circuit is effective at eliminating undesired stable equilibrium points in the presence of process and temperature variations. This approach is demonstrated by considering the well-recognized inverse Widlar bias generator/temperature sensor as an example.

A tunable SC bandpass delta-sigma modulator for multi-standard applications

This paper presents a double-sampling switched-capacitor (SC) tunable resonator for bandpass (BP) DeltaSigma modulators. The resonator is implemented with a single opamp to reduce the power consumption. In addition, the resonant frequency can be easily tuned by controlling the number of shunting capacitors. Based on the resonator, a fourth-order BP DeltaSigma modulator is proposed. With the tuning ability, the resonant frequencies of the two resonators in the modulator not only can be varied to the same center frequency for narrow-band applications, but also to the frequencies symmetric to the center frequency, one quarter of the sampling frequency, for wide-band applications. The BP DeltaSigma modulator is implemented in a 0.18 mum CMOS technology, and Matlab and HSPICE simulation results are presented to demonstrate the design concept.

A CMOS differential difference amplifier with rail-to-rail fully-differential outputs

The Differential Difference Amplifier (DDA) is well-known as a novel analog building block, which has 2 differential inputs. DDA-based circuits often provide high input impedance and simple external circuitry, and therefore are competitive to op amp-based circuits. In this paper, we present a design of a CMOS rail-to-rail fully-differential DDA (FDDA) in a 2 /spl mu/ CMOS process.

Novel full-integrated active filters using the CMOS differential difference amplifier

The CMOS differential difference amplifier (DDA) is a new versatile CMOS building block that has been recently introduced. It is a four-input device with an output that could be single-ended or differential. Applications of the DDA in the implementation of fully-integrated MOS active filters are presented. Novel simple DDA-based differential integrators with such attractive features as infinite input impedance and minimum component count with no matching requirements are presented and used in the design of higher-order filter structures.<<ETX>>