Jirasak Chanwutitum

Simple CMOS current-mode exponential function generator circuit

A low-power and low-voltage simple CMOS exponential function generator circuit is proposed. It is based on simple current mirrors able to operate at low supply voltage. The design of the circuit is based on Taylor series expression for realizing the exponential characteristic and of MOS transistor operating in the saturation region. Simulation using the PSPICE program with 0.5 mum CMOS model of MIETEC. The simulation results show a 16 dB linear output current range with the linearity error less than 1 dB at 1.5 V supply voltage.

Fully integrated current-mode quadrature sinusoidal oscillator circuit

This paper presents a new mixed-mode quadrature oscillator using one current controlled current conveyor (CCCII), one CCCII with controlled current gain and two grounded capacitors. The oscillation condition and the oscillation frequency can be controlled orthogonally and electronically by the bias currents of the CCCIIs. The circuit provides two quadrature voltage outputs and four quadrature current outputs and then can be classified as a mixed-mode oscillator. Simulation results that confirm the theoretical predictions are also given.

Electronically Tunable Voltage-Mode All-Pass Filter Using Simple CMOS OTAs

A new high input impedance electronically tunable voltage-mode first-order all-pass filter using three simple CMOS operational transconductance amplifiers (OTAs) and one grounded capacitor is presented. The corner frequency can be controlled electronically by adjusting the bias currents of OTAs. Critical component matching conditions are not required in the design. The use of a grounded capacitor and without resistor makes the proposed circuits ideal for integrated circuit implementation. The characteristics of the proposed circuit are simulated using PSPICE to verify the theory.

Single MCCCCTA-based mixed-mode third-order quadrature oscillator

This paper presents a new current-controlled mixed-mode third-order quadrature oscillator. The proposed structure employs one modified current-controlled current conveyor transconductance amplifier (MCCCCTA) and three grounded capacitors that can generate two quadrature voltage outputs and four quadrature current outputs. The use of grounded capacitor makes the proposed structure more suitable for integrated circuit implementation. The condition of oscillation and the frequency of oscillation can be controlled orthogonally and electronically by adjusting the biasing currents of the MCCCCTA. Simulation results verifying the theoretical analysis are also included.

Current-tunable current-mode universal filter using minimum elements

In this paper, a new electronically tunable current-mode universal filter with three inputs and single output employing only two translinear current conveyors and two grounded capacitors is presented. The proposed configuration provides lowpass, bandpass, highpass, bandstop and allpass current responses by choosing appropriate input signals without any component matching conditions, all at a high impedance output which enables easy cascading in the current-mode operation. The filter also offers independent electronic control of the natural frequency (ωo) and the quality factor (Q) through adjusting of the bias current and the current gain of the CCCII. The parameter sensitivities are all very low and the structure is very suitable for IC implementation. The characteristics of the proposed circuit are simulated using PSPICE to confirm the theory.

Voltage-mode lowpass, highpass, bandpass biquadratic filter using OTRAs

This paper presents a new voltage-mode universal biquadratic filter using operational transresistance amplifiers as active building block. The proposed circuit offers the following attractive advantages: realization of highpass, bandpass, lowpass filters, simultaneously, from the same circuit, no requirements for component-matching conditions for realizing all filtering function, low active and passive components. The workability of the proposed filter has been confirmed by PSPICE simulators.

An electronically tunable current-mode first-order allpass filter using a CCCCTA

This paper presents a new current-mode first-order allpass filter employing only one current-controlled current conveyor transconductance amplifier (CCCCTA), one capacitor and one MOS resistor. The pole frequency and the current gain of the filter can be controlled electronically by the bias currents of the CCCCTA. Also, both inverting and non-inverting allpass filters can be achieved into a single circuit. No component-matching condition requirements are needed for realizing allpass filtering function. PSPICE simulations using TSMC 0.25 μm CMOS is performed to examine the proposed filter.

Voltage-mode first-order allpass filter using single-ended OTAs and grounded capacitor

This paper presents a new electronically tunable voltage-mode first-order allpass filter using only three single-ended operational transconductance amplifiers (OTAs) and one grounded capacitor, which is highly suitable for integrated circuit implementation. The pole frequency of the filter can be tuned electronically by adjusting the transconductance value of the OTA. No component-matching conditions are also required for realizing allpass response. The characteristics of the proposed circuit are simulated using PSPICE simulations to confirm the theory.