Mustapha Alami

Universal current mode biquad implemented from two second generation current conveyors

The implementation for a nonideal gyrator is first considered. A universal second-order biquad filter, operating in current-mode is then described. The circuit exhibits simultaneously the lowpass, bandpass, and highpass transfers with unity gain. It uses two second generation current conveyors and four passive components only. Both its active and passive sensitivities are not dependent on Q. Their values are at the most equal to unity. SPICE simulation results are given to confirm the theoretical analysis. >

A precise macromodel for second generation current conveyors

A precise and general macromodel that allows one to describe the behavior of the second generation current conveyors for a frequency range up to about gigahertz is introduced. It includes four controlled sources and ten passive components. The ways to determine directly from measurements, the element values of a given conveyor are indicated. These values are given for the translinear implementation of a second generation current conveyor with positive transfer (CCII/sup +/), for /spl plusmn/10-V supply voltages and a bias current I/sub 0/ of 600 /spl mu/A. The simulation results obtained for this conveyor and for its macromodel were obtained in good agreement. The results of an inverting voltage mode amplifier implemented from a transimpedance op amp are also found in accordance for the amplifier designed from conveyors or from its deduced macromodel. Experimental verifications are also given for an active inductance implemented from the AD 844 transimpedance op amp.

Insensitive current-mode bandpass implementations-based nonideal gyrators

Two equivalent implementations for a nonideal gyrator designed from two current conveyors are described. From these basic implementations, two new configurations for second-order current-mode bandpass filters, which exhibit reduced active and passive sensitivities, are deduced. For one of them an additional transfer (low-pass or high-pass) is also available on the circuit. SPICE simulation results are given and discussed for the conveyors implemented in a translinear form. They confirm the validity of the theoretical analysis and underline the high performances of the filters. >

A versatile translinear cell-library to implement high performance analog ASICs

A translinear standard-cell approach in the field of analog ASICs is proposed. The translinear circuit principle is first summarized and an overview of the various properties which result from the implementation of translinear circuits is outlined. The concept of an hierarchic library, all in a translinear form, is introduced. Both basic cells, the current mirrors and the translinear mixed loops, appear to be the most important cells from which elementary building blocks (i.e. followers, conveyors. . .) can be implemented. Then, as demonstrated by some illustrative examples, high performance advanced macroblocks (i.e. amplifiers, filters. . .etc.) will be obtained. Simulated results, with SPICE, are given and discussed.<<ETX>>

Two new temperature compensated current sources

Two new temperature compensated current sources implemented from bipolar transistors have been inspected. They are both deduced from the schema of the cascode current mirror and necessitate a total of six or seven transistors. Their performance have been compared to an earlier introduced current source with four transistors. Simulation and experimental results are reported. They indicate that for 5 V supply the new current sources are both less temperature sensitive than the preceding one over the range -55/spl deg/C to +125/spl deg/C. One of them was also found particularly suited to design current sources with a low supply voltage approaching 2 V/sub BE/.

Insensitive current-mode biquad implementation based on translinear current conveyors

An insensitive current-mode filter, implemented from two second generation current conveyors is introduced. The circuit uses four passive components and exhibits simultaneously two 2nd order transfer functions: highpass and bandpass. A versatile ASIC implementation is proposed for the circuit. It includes the filter core and three supplementary followers in order that the lowpass, bandreject and allpass will also be available. SPICE simulation results, which confirms the theoretical analysis, are reported and discussed the conveyors being implemented in a translinear form.<<ETX>>

Two bandpass active filters with reduced sensitivities

A current-controlled current source and a voltage-controlled voltage source are used in conjunction with four passive components to implement second-order bandpass filters. The circuits, which exhibit reduced values for their active and passive sensitivities, can be used in a very large frequency range when the active elements are designed from high-performance bipolar arrays. Simulated results using SPICE, which confirm the theoretical analysis, are reported and discussed for active elements implemented in a translinear form. Experimental results are given indicating that the implementation compares favorably with conventional ones. >

Second generation current conveyors with enhanced input resistance

The design of wideband second generation current conveyors implemented from bipolar transistors is reconsidered in order to increase the value of their input resistance, R Y, at Y. This has been obtained by adding two supplementary transistors only. SPICE simulation results are given. They indicate that this improvement is obtained without damage to the other dynamic characteristics. The increase of R Y is also confirmed through measurements.

Brief communication Insensitive current-mode notch filter implemented from translinear conveyors

Abstract A filler-core operating in current mode and implemented from four passive components in conjunction with two current conveyors is described. It involves four second-order transfer functions which include a lowpass and a bandpass. A band reject is then obtained by adding two current followers to combine the output currents. Simulated results which confirm the theoretical analysis are discussed. The conveyors are implemented in a translinear form.