This paper proposes a topology-independent predistortion for filters using integrators. This employs integrators having the same structure, the same-value elements and an electrically controllable unity-gain frequency and compensates for the deviation of frequency characteristics due to excess phase shifts of integrators without knowledge of a filter topology. The effectiveness of the proposed method is demonstrated through SPICE simulations.

ISO and ITU-T have developed the standard concept of the Telecommunications Management Network (TMN). This standard does not, however, specify interface implementation. The user requires an Application Programming Interface (API) that bridges user application and the TMN concept to construct a TMN-based application. This paper proposes an object oriented API (OOAPI) that is suitable for TMN-based operations system implementation. OOAPI is one interface of the Common Management Information Service Element (CMISE), and uses the Common Management Information Protocol (CMIP). OOAPI is composed of two C++ programming language constructs: Data Object and Interface object "M_User". The Data Object makes it easier for the user to access management information. The M_User provides a connection-less CMISE interface because the OOAPI handles CMIP association automatically. The M_User also provides MO location-transparency by using the OSI Directory Service. This paper compares the existing MO location-transparency schemes with the OOAPI method, and clarifies the advantages of OOAPI. This paper also indicates results from OOAPI trials, and confirms that OOAPI has sufficient performance to implement highly effective TMN operations system.

A novel voltage-tunable linear 3-input CMOS Operational Transconductance Amplifier (OTA) suitable for onchip integration of advanced monolithic systems is proposed. When a 3-input OTA is needed, a conventional 3-input OTA uses two 2-input OTA's and either grounds one of the 4 input terminals or ties two terminals. This paper presents a method to reduce the number of MOS transistors and to save chip area by designing a 3-input OTA directly. A CMOS pair technique is introduced s a solution to minimize a matching problem for control voltage sources. Simulation results show that the active chip area of the proposed 3-input OTA is reduced by 25% compared to that of a conventional one. The proposed 3-input OTA is applied to a realization of an OTA-C filter to verify the effectiveness.

An over current protection method suitable for Fixed ON-time PFM (Pulse Frequency Modulation) Control DC-DC converters is proposed. It is based on inductor bottom current limiting, realized by monitoring the synchronous rectifier current and extending the OFF-phase of the main switch until it decreases to a predetermined limit, and can properly limit the output current even in case of short circuit. A Fixed ON-time PFM DC-DC converter with the proposed over current protection was designed and fabricated in CMOS IC. Its current limiting operation was verified with simulations and measurements.

Analog inverter is one of the most useful building blocks in analog circuits. This paper proposes an analog inverter consisting of a p-channel MOS (PMOS) and an n-channel MOS (NMOS) inverter and presents an application to all-pass filter realizations. The proposed circuit has a wide dynamic range by combining PMOS and NMOS inverters. When the proposed analog inverter is applied to an all-pass filter, the circuit configuration becomes simpler and occupies less chip area and power consumption.

Continuous-time MOSFET-capacitor filters have quite a serious problem, that is, MOS transistors' nonlinearity drastically reduces the filters' dynamic ranges. Czarnul proposed an MOS resistive circuit with high degree of linearity and solved this problem. The method, however, requires two capacitors for each integrator. Consequently, the chip area and manufacturing cost will increase. This paper proposes a new single capacitor integrator which can cancel the nonlinearity of transistors. The integrator is applied to a canonical continuous-time filter synthesis with high linearity. A total harmonic distortion less than 0.33% is obtained by SPICE analysis.

A novel linear voltage-to-current conversion circuit for a rail-to-rail input voltage is proposed in this paper. A pair of MOSFETs operating in plural regions are used for the conversion and a difference of their drain currents is used as an output current. The two MOSFETs work complemetarily and realize a rail-to-rail input range. The output current is linear in any input voltage from the ground potential to a power-supply voltage. Two types of circuit configurations which realize the proposed concept are given. From the viewpoint of area efficiency and linearity the proposed circuit is superior to a voltage-to-current converter previously proposed by the authors, which uses a set of three MOSFETs to achieve a rail-to-rail voltage-to-current conversion . The operation principle of the proposed method is confirmed through HSPICE simulations.

This paper proposes a realization of power factor function generator having an arbitrary base and power factor which are determined by the ratios of the currents provided from outside of the circuit. The circuit characteristics do not depend on any transistor parameters, temperature, and other environmental conditions. The circuit operation is based on current mode that has a capability of low power supply voltage operation below than 2.0 V. SPICE simulation has been carried out using 0.7 µm BiCMOS parameters and shows quite good transfer characteristics.

This paper proposes an algorithm for the design of FIR digital filters whose coefficients have CSD representations. The total number of nonzero digits is specified. A set of filters whose frequency responses have less than or equal to a given Chebyshev error have their coefficients in a convex polyhedron in the Euclid space. The proposed algorithm searches points where a coefficient is maximum or minimum in the convex polyhedron by using linear programing. These points are connected whih the origin to make a convex cone. Then the algorithm evaluates CSD points near these edges of the cone. Moving along these edges means the scaling of frequency responses. The point where the frequency response is the best among all the candidates under the condition of specified total number of nonzero digits is selected as the solution. Several techniques are used to reduce the calculation time. Design examples show that the proposed method can design better frequency responses than the conventional methods.

An equivalent MOSFET circuit with a wide input range is proposed. The proposed circuit is suitable for a realization of a wide input range under a low power supply voltage. The circuit consists of a MOSFET array and level shift circuits. The sum of drain currents of the MOSFET array is used as an equivalent drain current. The equivalent drain current is represented by K(VGS-VT)2 even when its drain-to-source voltage is quite small and some MOSFETs in the array are in the non-saturation region or the cut-off region. The input range of the proposed circuit realized by k-MOSFET array is k times as wide as that of a single MOSFET. It is confirmed through HSPICE simulations that the proposed circuit is effective in applications with a wide dynamic range.

This paper proposes a method for constructing an interface between an operations system and a workstation (OpS-WS interface) in a telecommunications management system based on TMN. To construct this interface, an appropriate communication protocol must be selected to perform management through efficient message exchange. The human machine interface provided by the WS should specify the managed objects. The interface also needs to be implemented so as to minimize the software revisions needed when the computer or its associated window system, or both, are changed. The proposed method addresses all these requirements. GUI components for realizing the HMI function are defined as Managed Objects as are communication network resources. Therefore, the communication protocol in TMN is defined as unique and it is possible to separate the HMI Interface from the OpS. CMIP is employed as the communication protocol to provide efficient message exchange. Software components that realize the human machine interface are selected so as to satisfy functional requirements specific to telecommunications management. The managed objects (MOs) and their relationships are investigated in order to represent these components appropriately. In the proposed method, the CMIP-based OpS-WS interface allows the OpS to take the manager role and the WS take the agent role. An implementation technique for MOs is also presented. The technique enables the software that implements MO behaviour to be coded easily. A prototype is built to confirm the correct operation of the proposed OpS-WS interface, and it is shown that CMIP requires fewer message exchanges to indicate alarms on the WS than other protocols. The proposed method is also advantageous because of its flexibility. That is, the WS software can be updated with little effort when the computer or its associated window system, or both, are changed.

This paper proposes a new charge pump to suppress spurious noise of phase-locked loops. The spurious noise is induced by charge injection generated from the parasitic capacitors associated with switches and the current-mismatch between the charging and discharging currents of the charge pump. A new charge pump is configured by adding an operational amplifier, a sample-and-hold circuit, and switches to a basic charge pump. During the idling time of the charge pump, the currents of the current sources are adjusted and the current-mismatch are reduced to 0.3%. Applying the proposed charge pump to a phase-locked loop, we can suppress the spurious noise by 18 dB compared with a PLL using a basic one.

In the correspondence discrete Wigner higher order spectra (WHOS) of harmonizable random signals are addressed and their relations with polyspectra (HOS) are illustrated. It is shown, that discrete WHOS of a random stationary signal do not reduce to the aliased polyspectra in a similar way as Wigner distribution (WD) reduces to the power spectrum of a random signal. Wigner 2nd-order time-frequency distribution of deterministic signals and the 3rd-order spectrum of stationary signals are presented in their modified forms to be used to estimate time-varying third-order spectrum of discrete nonstationary random harmonizable processes.

This paper discusses a new design method for 2-D variable FIR digital filters, which is an extension of our previous work for 1-D case. The method uses a 3-D prototype FIR filter whose cross-sections correspond to the desired characteristics of 2-D variable FIR filters. A 2-D variable-angle FIR fan filter is given as a design example.

A multi-path structure is proposed for reduction in effect of digital substrate noise which degrades analog circuit performance. As an example low-pass filters are implemented in a 0.18-µm CMOS process. 11-dBm reduction in digital substrate noise is achieved as compared with a conventional structure.

This paper proposes a novel method to realize highly linear MOS circuits using MOSFETs in the nonsaturation region. The proposed method is based on the cancellation of nonlinearity of two MOSFETs by using a current inversiontype negative impedance converter. First, grounded and floating resistor realizations are discussed. Next, by exploiting the MOS resistor circuits, gyrators and inductors are realized. As an application example, a third-order doubly-terminated LC filter is simulated. SPICE analysis shows low total harmonic distortions, excellent controllability and small gain error in the passband.

This paper presents a 7th-order channel-select filter for a spread-spectrum wireless receiver operating with a minimum power supply of 2.5 V. The channel-select filter implements a sharp transition from 2 MHz to 4 MHz and a stopband attenuation of 50 dB. The 7th-order filter is realized by a cascade of a passive RC integrator, a 3rd-order leapfrog filter, an operational amplifier based differentiator, a 2nd-order notch filter, and a 1st-order allpass filter. It is designed in a 0.35 µm single-poly BiCMOS process. Simulation results show feasibility of the proposed filter.

A high-speed transconductance-C-opamp integrator using a current-feedback amplifier is proposed. The integrator has good frequency response compared with a conventional transconductance-C-opamp integrator using a voltage-feedback amplifier. The current-feedback amplifier shifts the second pole of the proposed integrator to the upper frequency. The frequency is proportional to the current gain of the current-feedback amplifier. The proposed integrator can eliminate effects of the parasitics at the output node of the transconductance since the voltage at the node is fixed. One of the circuit examples of the proposed integrator is shown. Its validity is confirmed through HSPICE simulations. The proposed integrator works as predicted up to 260 MHz.

This paper proposes a fully balanced circuit structure with a zero common-mode gain. The common-mode gain of the proposed structure becomes theoretically zero with a perfect device matching. Even if a perfect device matching is not achieved, the common-mode signal can be sufficiently suppressed by the feedback loops provided with the structure. Based on this concept, an integrator is composed. Furthermore the concept can be directly applied to a filter design. The application results in reduced chip area. A design example of a second-order filter and simulation results verify the theoretical expectation.

In practical applications of digital filters it is more realistic to treat multiplier coefficients as finite intervals than restricting them to infinite or very long word-length representations. However, this can not be done it the frequency response performance under interval assumption is difficult to analyze. In this paper, it is proved that stable lattice allpass filters possess bounded continuous phase response when lattice parameters vary in bounded intervals. It is shown that sharp bounds on the interval phase response can be computed easily at an arbitrary frequency using a simple recursive procedure. Application of this property to the problem of finite word-length lattice allpass filter design is also discussed. By formulating this problem as an interval design it is possible to solve it efficiently independent of the number system used to represent multiplier coefficients.