Wiwat Kiranon

Multiphase sinusoidal oscillators using translinear current conveyors and only grounded passive components

A generalized multiphase sinusoidal oscillator is presented. The circuit realization uses the translinear bipolar second generation current-controlled conveyors to generate arbitrary n current signals equally spaced in phase. The proposed circuit consists of n multi-output current controlled conveyors and a current amplifier connected in cascade. The only passive component employed in each of the n conveyors is one grounded capacitor. The oscillation condition and oscillation frequency are independently controlled. The former depends only on the number of the phase signals of the oscillator. The dependency of the latter on the input resistance of the input ports of the current conveyors makes electronic tunability possible using the bias currents. The circuit also enjoys having simple structure and very low component count and it is highly suitable for monolithic implementation.

A linearized source-couple pair transconductor using a low-voltage square root circuit

This paper presents a CMOS transconductor linearization by connecting square-rooter to a source couple pair circuit. A novel square-rooting circuit is proposed for low voltage operation. The proposed transconductance circuit is compact and consumes lower quiescent power, compared with the existing transconductors using the same realization technique. The circuit performances verification by PSPICE simulations show good results as expected.

A novel FM demodulation scheme

An alternative approach for FM signal demodulation using differentiators is proposed. This mew approach, which can be realized in IC form, does not require an envelope detector or filter explicitly, thus enabling a fast and accurate response. Analytical and numerical results, in addition to experimental results, are presented.

A four-quadrant current-mode multiplier/divider building block

This paper presents a current-mode analog multiplier/divider based on current conveyors. The proposed circuit employs only two second-generation current conveyors with controlled current gains (KCCIIs). The circuit is active only; it does not require any external passive element. Then, it is suitable for implementation as integrated circuit. The proposed circuit can perform as either a four-quadrant multiplier or a four-quadrant divider without changing its topology. Simulation results of the circuit show good agreement with theoretical analysis. Applications such as modulator, full-wave rectifier and current amplifier are demonstrated to confirm the versatility of the proposed circuit.

An arbitrary power law device based on integrators

A new simple arbitrary power law device implemented from integrators along with the sample-and-hold technique is presented. The number of the integrators indicates the index of the power law. Part of the integrators determine an appropriate time interval to be used to control the sample-and-hold circuit to extract the correct output. To test the validity and value of the proposed method, numerous power law functions have been experimented. The experimental results show very close agreement with the theoretical analysis. In addition, the measurement output, possibly as large as a few volts, is obtained with extreme precision.

A novel derivative envelope detector

A novel and efficient algorithm for envelope detection based upon Hilbert transformation techniques is presented. The method relies exclusively on using differentiation to approximate the Hilbert transformation. The resulting detector is causal and does not require exact knowledge of carrier phase or frequency. The effectiveness of the method is illustrated through investigations of the estimation error performance in comparison with that of existing detectors. Simulation and experimental results demonstrate the superiority of the proposed method.