Krit Angkeaw

Realization of OTA-C current-mode universal filter based on two type integrators loop

A universal current-mode active filter based on 2 types of integrator, lossy and lossless integrators, is presented. The biquadratic transfer function is obtained by the two integrators loop. The proposed circuit employs only 2 multiple output OTAs (MO-OTA) and 3 capacitors. The parameter Qp can be wide-range tuned independent from the omegap either changing of capacitor and transconductance gains. Moreover, the four different kind filter functions as lowpass, highpass, bandpass and band-reject response can be also obtained without changing circuit topology. The parameters omegap can be electronically tuned through adjusting the transconductance gains of the OTAs. The simulation results have been carried out by P Spice.

Floating-capacitance multiplier based on CCDDCCs and its application

This paper proposes a new floating capacitance multiplier using three Current Control Differential Difference Current Conveyors (CCDDCCs) with CMOS technology and one grounded capacitor. The circuit can be electronically tuned through bias currents of CCDDCC without external resistor connections and temperature effects do not affected to the capacitance characteristic. The realization is suitable for further integration. The third-order elliptic LPF is included as an application. The simulations results of proposed capacitance multiplier and its applications are carried out by PSpice that agrees well with the theoretical expectations.

Tunable PID controller based on log-domain circuits

Current-mode proportional plus integral plus derivative (PID) controller based on log-domain concept is presented in this paper. The parameters of P, I, and D blocks can be independently controlled through bias currents. Only grounded capacitors are employed as a passive element for achieving the time-constant of I and D controllers. In each block of I and D controllers are easily constructed by using 10 bipolar transistors and a grounded capacitor except P controller uses only 4 bipolar transistors without any resistors. Thus, it is suitable for integrated circuits realization. Single power supply voltage 2.5V is used. The characteristics of PID are simulated is by SPICE. The demonstrated results are in good agreement with the theoretical expectations.

Tunable current-mode log-domain universal filter

This paper describes the design of a current-mode universal filter based on log-domain filtering concept. The circuit is a direct realization of a first-order differential equation for obtaining the two integrators loop structure. Lossless integrators are realized by log-domain lossy integrators. The proposed filter comprises only two grounded capacitors and sixteen transistors. Frequency response of the proposed filter can be instantaneously controlled over a very wide frequency range by controlling current. Quality factor is independently controlled by another current. It can be seen that the proposed circuit suites for high-frequency applications. A validated BJT model that used in simulation is operated by a single power supply as low as 2.5V. The wide-range frequency response is controlled over five decades of current controlled.

Log-domain current-mode third-order sinusoidal oscillator

This paper describes the design of the third-order sinusoidal oscillator based on log-domain filtering concept. The circuit consists of two inverting lossy integrators and one inverting lossless integrator. The circuit employs only NPN-transistors. This proposed circuit can be instantaneously controlled over a very wide frequency range by adjusting bias currents for oscillation frequency which are indicated proposed circuit suitability in high-frequency applications. The oscillation condition and frequency of oscillation can be tuned by bias current. Sinusoidal frequency output can be obtained up to 100MHz with low THD and low number of transistors. Characteristics of this circuit are simulated using PSpice and they are found in agreement with the theory.

Log-domain quadrature sinusoidal oscillator based on lossless integrator and all-pass filter

A log-domain current-mode quadrature sinusoidal oscillator based on all-pass filter and lossless integrator is presented. The oscillator is realized by a first-order differential equation for obtaining all pass filter and lossless integrator. The proposed oscillator can be electronically tuned by adjusting bias currents. The proposed oscillator contains 18 NPN transistors, 2 grounded capacitors and 11 bias currents for achieving low-power and fast response. A validated BJT model is used in SPICE simulation operated from a single power supply as low as 2.5V. The oscillation frequency is controlled over four decades of frequency. The total harmonic distortion of signal output is obtained around 0.55%. The oscillation frequency can be operated more than 100MHz which enables fully integrated in telecommunication systems and suitable for high-frequency applications. SPICE simulation results are included.

CCCII-based multiphase sinusoidal oscillator employing high-pass sections

This paper proposes a new approach to implement a multiphase sinusoidal oscillator by using loop-back of n-cascaded high-pass sections form. Two CMOS Current-controlled Current Conveyors (CCCII) and a grounded capacitor are constructed as a current-mode high-pass section for each phase. The orthogonally of oscillate condition and frequency of oscillation are obtained with their electronically controllable through current biased of CCCII. Multiphase sinusoidal outputs can be obtained with equally spaced in phase, 360/n degree. Third-order oscillator is raised up to confirm the theoretical agreement. Low-harmonic distortion of achieved sinusoidal output obtains less than 0.9%. The performances are carried out by PSpice for confirm its characteristics.

Low-component-count current-mode Universal Filter based on active-only Lossy and Lossless Integrators

An universal current-mode active-only filter using the biquadratic transfer function is proposed. The proposed circuit is realized by lossy and lossless integrators with minimize active components count without external passive elements. The different kinds of filter functions as lowpass, highpass, bandpass and band-reject response can be obtained without changing circuit topology. The proposed circuit implementation is realized by using MOS transistors, CMOS MO-OTAs, and CMOS OPAMPs. The parameters wp can be tuned electronically through adjusting the transconductance gains of the OTA or electronic resistor power supplies. The simulation results are given by PSpice.