Abstract: The predistortion circuit with concave characteristic is developed from a novel functional model for class-AB solid-state bipolar amplifiers. The model, based on a Fourier sine-series is simple and can provide closed-form expressions for the intermodulation products resulting from exciting the power amplifier by a multi-sinusoidal signal. The special case of a two-tone equal-amplitude signal is considered in detail. The present model can be used to build a database for the intermodulation performance of the class-AB bipolar SSPAs excited by a multi-sinusoidal signal. Using this database, the diode-based predistortion circuit with concave characteristic for linearizing the class-AB solid-state power amplifier is designed.

Abstract: A memristor-based emulator including a memristor circuit for use in digital modulation that includes a first current feedback operational amplifier (CFOA) having multiple terminals in communication with a capacitor Cd and in further communication with a resistor Ri. A second CFOA having multiple terminals is in communication with the first CFOA and is adapted to be in further communication with a voltage vM to provide an input current iM for integration by a capacitor Ci. A nonlinear resistor is in communication with the second CFOA. A third CFOA having multiple terminals is in communication with the nonlinear resistor and is in further communication with the first CFOA and a resistor Rd. The third CFOA and the resistor Rd act as an inverting amplifier associated with the nonlinear resistor to increase a current gain to increase a difference between ON and OFF values of a resistance of a realized memristor.

Abstract: The programmable CMOS-based nonlinear function synthesizer is a circuit that assumes that the required nonlinear function can be approximated by the summation of hyperbolic tangent (tan h) functions with different arguments. Each term of the tan h function expansion is realized using a current-controlled current-conveyor (CCCCII), or an operational transconductance amplifier (OTA)) with a different bias current. The output weighted currents of these CCCCIIs or OTAs are algebraically added to produce the output current. The present circuit can be easily integrated, extended to include higher order terms of the tan h-function expansion and programmed to generate arbitrary hard nonlinear functions. By controlling the bias current and without changing the aspect ratios of the transistors, various tan h functions with different arguments from the same topology can be obtained.

Abstract: A current controlled operational transconductance amplifier based sinusoidal oscillator circuit that provides oscillation based on the transconductance and parasitic capacitance of the operational transconductance amplifier without externally connected capacitances. The oscillation frequency is adjusted through a variable current source or a variable resistor with a DC voltage source.

Abstract: A current-feedback operational-amplifier Based Relaxation oscillator provides oscillation based on a current feedback operation amplifier and two external resistors which exhibit a low output impedance terminal. This current-feedback operational-amplifier Based oscillator is used as a component for a capacitive, resistive and capacitive-resistive sensor electronic interfacing circuit.

Abstract: A programmable sinusoidal oscillator circuit is a sinusoidal oscillator circuit that includes a current-feedback operational-amplifier (CFOA) operably connected to two operational transconductance amplifiers (OTAs), two capacitors and a resistor. The programmable sinusoidal oscillator circuit enjoys electronic orthogonal tuning of the frequency and the condition of oscillation by adjusting the biasing currents (voltages) of the OTAs, as well as providing a low output impedance.

Abstract: The nonlinear systems measurement system includes two signal generators generating different sinusoidal frequencies. A spectrum analyzer measures all signals. A single software program synchronizes the instruments. The fetched measurements are kept in data registers in correct sequence for feeding into two curve fitting routines. The sinusoidal signals are fed to a suitable combiner for the expected frequencies and dynamic range of the UUT. The combined signal is applied to the UUT. Via a software-controlled single-pole, triple-throw RF switch, the amplitude of the UUT output and the two input signals are measured at every power step as amplitude I1 and amplitude I2. The amplitude of the output component from the UUT at f1-f2 is measured as IMD2 and the output component at 2f1-f2 is measured as IMD3. The measured I1 and IMD2 are fed to the curve-fitting routine 1, yielding r1. The measured I2 and IMD3 are fed to curve-fitting routine 2, yielding r2.

Abstract: The current-feedback operational amplifier-based sinusoidal oscillator provides oscillations based on a single external resistor and a single external capacitor, which exploit the internal parasitic components of the CFOA. The external resistor and external capacitor are passive, externally connected, and grounded.

Abstract: The CMOS programmable non-linear function synthesizer utilizes CMOS current-mode electronics to provide synthesis of arbitrary analog functions. The circuit approximates a seventh-order Taylor series expansion to synthesize an arbitrary nonlinear function. Each term of the Taylor series expansion is realized using a current-mode basic building block, and the output weighted currents of these basic building blocks are algebraically added in addition to a DC current, if needed. The CMOS current mode electronic circuit can be easily integrated, extended to include higher order terms of the Taylor series, and programmed to generate arbitrary nonlinear functions.

Abstract: The CMOS programmable non-linear function synthesizer utilizes CMOS current-mode electronics to provide synthesis of arbitrary analog functions. The circuit approximates a seventh-order Taylor series expansion to synthesize an arbitrary nonlinear function. Each term of the Taylor series expansion is realized using a current-mode basic building block, and the output weighted currents of these basic building blocks are algebraically added in addition to a DC current, if needed. The CMOS current mode electronic circuit can be easily integrated, extended to include higher order terms of the Taylor series, and programmed to generate arbitrary nonlinear functions.

Abstract: The arbitrary power law function generator uses an equal number of exponential and logarithmic circuits, e.g., two exponential and two logarithmic circuits, which are current-mode, current-controlled circuits that provide positive, negative, integer, or non-integer powers independent of temperature. Moreover, the circuit can operate from a DC power supply as low as ±1.5V. SPICE simulation results using practical bipolar junction transistor (BM parameters are included to confirm the feasibility of the function generator.

Abstract: The balanced output signal generator uses four interconnected plus-type second-generation current conveyors, a couple of load resistors and a single input resistor that can provide both current- and voltage-mode outputs. No matching conditions are required.

Abstract: The balanced output signal generator uses four interconnected plus-type second-generation current conveyors, a couple of load resistors and a single input resistor that can provide both current- and voltage-mode outputs. No matching conditions are required.

Abstract: The 555 timer-based phase-to-voltage converter is a circuit that can be used for phase-to-voltage conversion for phase angles in the range between 0 and 2?. A first input signal triggers the 555 timer. A second input signal resets the 555 timer, and thus an output signal having a pulse width proportional to the phase difference between the first and second input signals is formed at the output of the 555 timer. A low pass filter may be placed at the output to pass a DC voltage having a magnitude proportional to the phase difference between the first and second input signals for phase angles between 0 and 2?.

Abstract: The voltage-controlled dual-slope square and triangular waveform generator is an electronic circuit that includes a plus-type second-generation current conveyor operably connected to a single operational amplifier. At the input stage to the operational amplifier, two metal-oxide semiconductor (MOS) transistors are configured as switches. Three resistors and a grounded capacitor are included in the electronic circuit, thereby maintaining a low component count. The leading and trailing slopes of the waveform are independently adjustable by selection of the voltages V1 and V2 that are selectively connectable to the y-input of the CCII+ via switching action of the MOS transistors. The frequency of the waveform is adjustable via the voltage divider ratio between the output and noninverting input of the operational amplifier. The simple and elegant nature of the circuit design provides a low-cost waveform generator that can be adjusted both for frequency and for independent leading edge and trailing edge slopes.

Abstract: The universal CMOS current-mode analog function synthesizer is based on approximating the required function using its sixth-order Taylor series expansion. These approximations can be implemented by adding the weighted output currents of a number of basic building blocks built around a basic current squarer, and a constant current. The circuit can simultaneously realize thirty-two different mathematical functions and can be easily expanded to accommodate many others.

Abstract: The universal CMOS current-mode analog function synthesizer is based on approximating the required function using its sixth-order Taylor series expansion. These approximations can be implemented by adding the weighted output currents of a number of basic building blocks built around a basic current squarer, and a constant current. The circuit can simultaneously realize thirty-two different mathematical functions and can be easily expanded to accommodate many others.