Amphawan Chaikla

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

A high-speed algorithmic ADC

A method for realizing high-speed algorithmic analogue-to-digital converter (ADC) is presented in this paper. The realization method based on the proposed absolute function circuit, which performs a low-distortion in the transfer characteristic, is utilized. The proposed ADC is simple, small in size and suitable for implementing a high-resolution ADC. Performances of the proposed circuit are discussed in detail and confirmed through Cadence Spectre simulation results.

Digital Technique to Generate Variable and Multiple PWM Signals

In this paper, we present a digital technique to generate pulse width modulation (PWM) signal using counters, comparators, and latching circuits implemented by Verilog HDL program based on FPGA. The proposed technique can simultaneously generate variable and multiple PWM outputs with parallel processing. Setting each reference-input signal can independently and easily vary the pulse width of each generated signal. The FPGA-based implementation can minimize the size of hardware. The communication can be easily done via a personnel computer. Application example in the design of the proposed technique as the parallel processing is also included.

Improving suspension manufacturing yield using polynomial regression

This paper proposes the technique to adjust the roll and pitch directions of the flex suspension assembly in a disk drive production. The adjustment is accomplished using a number of laser beam projections, which can be approximated using the polynomial regression model of the existing measured roll and pitch directions. Information derived from the analysis can help improve manufacturing yield. The performances of the proposed technique were observed using the flex suspension assembly plant in Thailand as an illustrative case study. The experimental results are given to support the improving manufacturing yields and some economic benefits of the proposed technique.

OTA-based Gray-code Algorithmic ADC

This paper presents a Gray-code algorithmic analog-to-digital converter (ADC). The proposed circuit comprises of OTAs, diodes, resistors, and voltage comparator to synthesize a triangular-like DC transfer characteristic and a digital output for an one-bit cell ADC. The design structure is simple and flexible. An N-bit resolution can be implemented by cascading the N proposed one-bit cells. Experimental results verifying the circuit performances are agreed with the theoretical values

Energy saving based on upgrading cooling system in composite plant

This paper presents an upgrading cooling system to minimize the energy costs based on the energy saving. The proposed technique uses a plate-and-frame heat exchanger to replace the traditional worm cooler. The performances of the proposed upgrading were observed using a cooling system of the composite plant in Thailand as an illustrative case study. The experimental results demonstrating the saving in energy costs and some economic benefits of the proposed technique are included.