Vanchai Riewruja

Accurate CMOS-based current conveyors

An integrable circuit technique for implementing both positive and negative second-generation current conveyors (CCII) is described. Since the proposed circuits consist of a differential pair, current sources, and current mirrors, the realization method can result in a fully integrated current conveyor. The realization method is suitable for fabrication in CMOS technology. The performance of the CMOS-based CCIIs is discussed in detail. The basic performances are demonstrated and simulation and experimental results are presented. The DC transfer characteristics for converting resistors are linear over the total dynamic range. >

Temperature-insensitive voltage-to-current converter and its applications

A novel voltage-to-current (V/I) converter circuit is proposed, which is based on an operational transconductance amplifier (OTA) integrated circuit. The V/I transconductance gain is insensitive to temperature and the input differential voltage swing limitation of the OTA integrated circuit is alleviated. New circuits for the temperature-insensitive general-grounded resistance converter, instrumentation amplifier, electronically tunable gyrator, and analog multiplier are presented. Experimental and simulation results that demonstrate the performances of the V/I convertor and its applications are also included.

Integrable CMOS sinusoidal frequency doubler and full-wave rectifier

A CMOS integrable circuit technique for the realization of both a sinusoidal frequency doubler and a full-wave rectifier is described in this paper. The realization method makes use of the characteristic of a simple CMOS class AB amplifier configuration. Simulation and experimental results demonstrating the circuit performance are also included.

A low-voltage wide-band CMOS precision full-wave rectifier

A simple integrable circuit for implementing a precision full-wave rectifier circuit in CMOS technology, which can be operated from a low-voltage power supply, is described. The realization method is based on the use of a MOS class AB configuration to improve the high frequency performance. The circuit exhibits a very sharp corner in the dc transfer characteristic. Simulation results showing the performance of the proposed circuit are also presented.

Sinusoidal frequency doubler and full-wave rectifier based on translinear current-controlled current conveyors

A circuit design technique that employs translinear current-controlled current conveyors as active circuit elements to design a sinusoidal frequency doubling and full-wave rectifying circuit is proposed. The circuit can realize the sinusoidal frequency doubler and full-wave rectifier without changing the circuit configuration. The proposed frequency doubling and rectifying action is exploited from the translinear characteristic of the current conveyor. Simulation and experimental results are given to confirm the theoretical predictions.

An Amplitude Detector for Variable Frequency Sinusoidal Signals

In this paper, a JK-flip-flop-based logic circuit is described. Using two output signals of this designed logic circuit to control a buffered peak detector followed by a simple sample-and-hold circuit in sequential operation, a sinusoidal amplitude detector is proposed. The proposed detector allows the frequency of input signals to be varied over a wide range. Experimental results verifying the performances of the proposed circuit are in close agreement with the expected values

Simple square-root extractor using op amps

This paper presents the simple and inexpensive method to implement a square-root extractor for voltage input signal. The proposed extractor is based on the use of two operational amplifiers (op amps) as only active elements. The proposed technique employs the op amp supply-current sensing to achieve an inherently quadratic characteristic. The low-output distortion in output signal can be achieved. Experimental results verifying the characteristic of the proposed circuit are also included.

Integrable CMOS-base realization of current conveyors

Simple integrable circuits for implementing both positive and negative second generation current conveyors (CCII) are described. The realization method is suitable for fabrication using CMOS technology. Simulation and experimental results demonstrating the characteristics of the method are also included.

Simple square-rooting voltage-to-frequency converter using opamps

This paper presents a simple method based on commercially available operation amplifiers (Opamps) for realizing the square-rooting voltage-to-frequency converter (VFC). The realization of square-root function is provided through the use of the opamp supply-current sensing, which utilizes an inherent quadratic characteristic of the opamp class-AB output state. Experimental results verifying the performances of the proposed square-rooting VFC are included.

Electronically adjustable phase shifter using OTAs

First-order phase shifter using operational transconductance amplifiers (OTAs) as active elements is presented in this paper. The corner frequency of the proposed phase shifter can be adjusted by electronic means. The purpose of this paper is emphasized on simple configuration and low cost. The phase response between input and output signals against the operating frequency is varied from 180 to 0 degrees of phase lead. The principle of the proposed circuit is confirmed by simulation and experimental results. To verify the proposed circuit performance, the sinusoidal oscillator is provided for circuit application.