Design of Mixed-Mode Analog PID Controller with CFOAs.

The design of a mixed-mode proportional-integral-derivative (PID) controller circuit using current-feedback operational amplifiers (CFOAs) as active components is proposed. With the same circuit topology, the proposed configuration of three CFOAs, four resistors, and two capacitors is capable of performing the PID controller in each of the following four modes: voltage mode, trans-admittance mode, current mode, and trans-impedance mode. Numerous mathematical analyses are conducted to determine the controller's performance under both ideal and non-ideal conditions. Additionally, the mixed-mode second-order lowpass filter is suggested and also used to examine the workability of the proposed mixed-mode PID controller in a feedback control structure. The proposed PID controller is implemented with the commercially available IC-type CFOA AD844, and the simulation results are presented to illustrate the functionality of the controller and its closed-loop control system. According to the findings, the total power consumption of the proposed PID controller is 0.348 W, with symmetrical supply voltages of ±9 V. It also has a temperature variation of less than 0.2% over the AD844's usable range. Monte Carlo statistical analysis results revealed that the gain responses of the controller exhibited a deviation of no more than 7.72% from the theoretical value. The controlled filter in a closed-loop control system has a 43% faster rise time and peak time than the uncontrolled filter in all four modes of operation. It also has a steady-state error less than 0.2 mV for voltage responses and 0.72 µA for current responses.

Single VDGA-Based Mixed-Mode Electronically Tunable First-Order Universal Filter.

This article presents a mixed-mode electronically tunable first-order universal filter configuration employing only one voltage differencing gain amplifier (VDGA), one capacitor, and one grounded resistor. With the appropriate selection of the input signals, the proposed circuit can realize all three first-order standard filter functions, namely low pass (LP), high pass (HP), and all pass (AP), in all four possible modes, including voltage mode (VM), trans-admittance mode (TAM), current mode (CM), and trans-impedance mode (TIM), from the same circuit structure. It also provides an electronic tuning of the pole frequency and the passband gain by varying transconductance values. Non-ideal and parasitic effect analyses of the proposed circuit were also carried out. PSPICE simulations and experimental findings have both confirmed the performance of the design. A number of simulations and experimental observations confirm the viability of the suggested configuration in practical applications.

Single VDGA-Based Mixed-Mode Universal Filter and Dual-Mode Quadrature Oscillator.

This article presents the circuit designs for a mixed-mode universal biquadratic filter and a dual-mode quadrature oscillator, both of which use a single voltage differencing gain amplifier (VDGA), one resistor, and two capacitors. The proposed circuit has the following performance characteristics: (i) simultaneous implementation of standard biquadratic filter functions with three inputs and two outputs in all four possible modes, namely, voltage-mode (VM), current-mode (CM), trans-admittance-mode (TAM), and trans-impedance-mode (TIM); (ii) electronic adjustment of the natural angular frequency and independently single-resistance controllable high-quality factor; (iii) performing a dual-mode quadrature oscillator with simultaneous voltage and current output responses; (iv) orthogonal resistive and/or electronic control of the oscillation condition and frequency; (v) employing all grounded passive components in the quadrature oscillator function; and (vi) simpler topology due to the use of a single VDGA. VDGA non-idealities and parasitic elements are also investigated and analyzed in terms of their influence on circuit performance. To prove the study hypotheses, computer simulations with TSMC 0.18 µm CMOS technology and experimental confirmatory testing with off-the-shelf integrated circuits LM13600 have been performed.

Simple BiCMOS CCCTA design and resistorless analog function realization.

The simple realization of the current-controlled conveyor transconductance amplifier (CCCTA) in BiCMOS technology is introduced. The proposed BiCMOS CCCTA realization is based on the use of differential pair and basic current mirror, which results in simple structure. Its characteristics, that is, parasitic resistance (R x) and current transfer (i o/i z), are also tunable electronically by external bias currents. The realized circuit is suitable for fabrication using standard 0.35 µm BiCMOS technology. Some simple and compact resistorless applications employing the proposed CCCTA as active elements are also suggested, which show that their circuit characteristics with electronic controllability are obtained. PSPICE simulation results demonstrating the circuit behaviors and confirming the theoretical analysis are performed.

SFG synthesis of general high-order all-pass and all-pole current transfer functions using CFTAs.

An approach of using the signal flow graph (SFG) technique to synthesize general high-order all-pass and all-pole current transfer functions with current follower transconductance amplifiers (CFTAs) and grounded capacitors has been presented. For general nth-order systems, the realized all-pass structure contains at most n + 1 CFTAs and n grounded capacitors, while the all-pole lowpass circuit requires only n CFTAs and n grounded capacitors. The resulting circuits obtained from the synthesis procedure are resistor-less structures and especially suitable for integration. They also exhibit low-input and high-output impedances and also convenient electronic controllability through the g m-value of the CFTA. Simulation results using real transistor model parameters ALA400 are also included to confirm the theory.

Gm-realization of controlled-gain current follower transconductance amplifier.

This paper describes the conception of the current follower transconductance amplifier (CFTA) with electronically and linearly current tunable. The newly modified element is realized based on the use of transconductance cells (G(m)s) as core circuits. The advantage of this element is that the current transfer ratios (i(z)/i(p) and i(x)/i(z)) can be tuned electronically and linearly by adjusting external DC bias currents. The circuit is designed and analyzed in 0.35 µm TSMC CMOS technology. Simulation results for the circuit with ±1.25V supply voltages show that it consumes only 0.43 mw quiescent power with 70 MHz bandwidth. As an application example, a current-mode KHN biquad filter is designed and simulated.