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On the Design of Differential Difference Transconductance Amplifier (DDTA) and Its Applications
(2026-03-01)
Channumsin, Orapin
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Yaruan, Panurut
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Tangsrirat, Worapong
This paper presents the design and implementation of a novel active building block termed the Differential Difference Transconductance Amplifier (DDTA). The proposed DDTA integrates the characteristics of the Differential Difference Amplifier (DDA) and the Transconductance Amplifier (TA) to enhance flexibility in analog signal processing. It comprises three TA stages—two forming a DDA structure and one functioning as a TA—allowing independent electronic tuning of transconductance gain (gm). The DDTA features a simple architecture, wide input capability, extremely high input impedance, and high output resistance at both intermediate and output current terminals, enabling accurate current-mode signal processing with minimal loading effects. To demonstrate its versatility, a voltage-mode universal biquadratic filter and dual-mode quadrature oscillator, both based on a single DDTA and utilizing only two capacitors, have been designed and simulated. PSPICE simulation results confirm wide linear voltage-to-current conversion, wideband transconductance performance, and robust impedance characteristics, all in excellent agreement with theoretical predictions. These features validate the effectiveness and practicability of the proposed approach for modern analog circuit designs.
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Low-Cost Smartphone-Controlled Exercise Machine for Arm and Leg Muscles
(2026-01-01)
Pimpol, Jirapun
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Channumsin, Orapin
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Pattoom, Pongwat
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Weawthaisong, Wipakpong
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Singusaha, Orathai
This work proposes the design of a smart exercise machine for arm and leg muscles. The designed muscle arm and leg exercise machine can be controlled wirelessly through a smartphone application, which features a 3-level speed adjustment function. The motor speeds for arm muscle exercises are defined as 180, 210, and 240 rpm, while the speeds for leg muscles are set as 240, 270, and 300 rpm, respectively. In addition, the proposed machine incorporates a time function for muscle exercise and it can control the spin direction to rotate either forward or backward, depending on the requirement, using a microcontroller. Furthermore, it can display the distance traveled by an application on a smartphone. The experimental operation of the automatic arm and leg exercise machine revealed that it could accomplish its intended functionality.
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Design and Synthesis of Capacitance Multiplier Using LT1228s and a Grounded Capacitor
(2026-01-01)
Channumsin, Orapin
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Roongmuanpha, Natchanai
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Likhitkitwoerakul, Nutcha
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Tangsrirat, Worapong
In this study, the design and synthesis of a grounded capacitance multiplier is discussed. The proposed circuit consists of two commercially available integrated circuits (ICs) named LT1228, together with a single grounded capacitor as a passive element. The transconductance gain of LT1228 allows for electronic control of the simulated equivalent capacitance value. The LT1228 transconductance gain is easily adjusted through the external bias current, which has a wide adjustable range of 1 µA to 1 mA. No component matching is required for the designed simulator. A non-ideal analysis of the proposed circuit has been investigated in detail. The workability of the proposed circuit and its application example as a first-order lowpass filter has been confirmed with the theoretical findings through PSPICE software. The results indicate that the proposed simulator has excellent performance and matches the theory.
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Grounded Immittance Simulation and PID Control Application
(2026-01-01)
Channumsin, Orapin
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Unhavanich, Sumalee
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Roongmuanpha, Natchanai
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Tangsrirat, Worapong
This communication introduces a grounded immittance function simulator. The circuit employs a single differential voltage to current converter (DVTC) in association with three passive elements. The grounded series type RL and RC simulator can be realized by selecting the proper position of all passive elements. The equivalent resistance, inductance, and capacitance accomplished from the proposed circuit can be adjusted with a passive resistor. DVTC non-idealities on the proposed simulator are also discussed in detail. The voltage mode PID controller has been suggested as an application using the proposed simulator. The performance of the proposed simulator and controller applications have been carried out through PSPICE simulation. The results are certified by the theoretical prediction.
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VDGA-Based Resistorless Mixed-Mode Universal Filter and Dual-Mode Quadrature Oscillator
(2025-05-01)
Channumsin, Orapin
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Tangjit, Jetwara
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Pukkalanun, Tattaya
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Tangsrirat, Worapong
This study introduces an electronically tunable resistorless mixed-mode universal filter and dual-mode quadrature oscillator configuration utilizing merely two voltage differencing gain amplifiers and two grounded capacitors. The suggested filter can perform all generic biquadratic filter functions in all four modes: voltage mode, trans-admittance mode, current mode, and trans-impedance mode, while utilizing the same design. The pole frequency and the quality factor can be tuned electronically and orthogonally by means of the transconductances of the voltage differencing gain amplifier. The dual-mode quadrature oscillator featuring both voltage and current outputs can also be obtained from the proposed filter core. It additionally provides separate electronic control of the oscillation condition and frequency. Several PSPICE simulations with the TSMC 0.18 μm CMOS model confirm the feasibility of the proposed configurations. Both proposed circuits were experimentally evaluated using commercially available integrated circuit LM13600s. Both simulation and experimental results have validated the performance of the design.
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Design and Experimental Validation of the Versatile Voltage Conveyor-Based Novel Mixed-Mode Universal Filter Configurations and Quadrature Oscillator
(2025-01-01)
Faseehuddin, Mohammad
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Shireen, Sadia
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Channumsin, Orapin
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Bhanja, Mousumi
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Tangsrirat, Worapong
In this research, a truly mixed-mode multi-input single-output (MISO) universal filter is designed using a second-generation voltage conveyor (VCII) and an operational transconductance amplifier (OTA). The filter is designed with three VCIIs, three OTAs, two resistors and two grounded capacitors. It is capable of producing various responses including low-pass (LP), high-pass (HP), band-pass (BP), band-reject (BR) and all-pass (AP). The filter can also function in all four possible modes of operation: voltage mode (VM), current mode (CM), trans-admittance mode (TAM) and trans-impedance mode (TIM). The merits of the filter comprise (i) no requirement for matching passive component; (ii) use of grounded capacitors; (iii) low-output impedance in VM and TIM operations; (iv) high-output impedance in CM and TAM operations; and (v) the capacity to tune the quality factor (Q) and the natural angular frequency (ω<inf>o</inf>). A dual-mode quadrature oscillator is additionally derived from the proposed filter core. The condition for oscillation and the oscillation frequency can be regulated independently. Moreover, a novel VCII-exclusive mixed-mode filter topology is developed from the designed filter. A study is performed on the non-ideal gains and parasitic effects of the circuits. The designed filters and oscillators are validated in the Cadence design suite using a 0.18 μm real CMOS process. The filters are validated at a frequency of 1.59 MHz, and the oscillator is examined at 1.25 MHz at supply voltages of ±0.9 V. The mixed-mode filter has also been experimentally tested using commercial integrated circuits (ICs), specifically AD844 and LM13700. The theoretical results are found to exhibit a close correlation with the simulated ones.
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VDGA-Based Resistorless Dual-Mode SIMO Biquadratic Filter
(2024-01-01)
Pimpol, Jirapun
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Channumsin, Orapin
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Pukkalanun, Tattaya
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Tangsrirat, Worapong
This work introduces the synthesis of a resistorless single-input multiple-output dual-mode biquadratic filter. The proposed circuit can perform both voltage-mode and current-mode operations without making circuit modifications. It consists of two voltage differencing gain amplifiers (VDGAs) as an active element, together with only two grounded capacitors as passive elements. Furthermore, it has the capability to produce the conventional biquad filter functions - namely, simultaneous highpass, bandpass, and lowpass responses - in either voltage or current mode. The proposed dual-mode biquad filter can electronically adjust significant filter parameters. TSMC 0.25-μ m CMOS process parameters are utilized in computer simulation to validate the theoretical expectations.
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Single Voltage Differencing Gain Amplifier-Based Dual-Mode Quadrature Oscillator Using Only Grounded Passive Components
(2022-01-01)
Channumsin, Orapin
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Bhardwaj, Kapil
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Srivastava, Mayank
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Tangsrirat, Worapong
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Petchmaneelumka, Wandee
This article describes the compact quadrature sinusoidal oscillator, which produces both voltage and current quadrature outputs at the same time. By utilizing a voltage differencing gain amplifier (VDGA) as an active element, the proposed dual-mode quadrature oscillator is realized with only three grounded passive elements, namely one resistor and two capacitors. The adjustment rules for the condition of oscillation and the frequency of oscillation are orthogonally controllable by the independent VDGA bias currents. Non-ideal influences on the circuit’s behavior are also examined in detail. PSPICE-based computer simulation was used to evaluate the theoretical hypotheses of circuit functioning.
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Resistorless Phase Shifter Realization with a Single VDGA
(2022-01-01)
Pimpol, Jirapun
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Channumsin, Orapin
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Tangsrirat, Worapong
This paper discusses an electrically adjustable phase shifter that uses only one voltage differencing gain amplifier (VDGA) and one floating capacitor. This circuit does not desire any external resistors, which results in a least number of active and passive components. The proposed phase shifter circuit provides first-order allpass filter responses, with the external DC currents used to electronically modify the passband gain, pole frequency, and phase response. The simulation results of the proposed phase shifter circuit insist the theoretical evidence's applicability.
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Automatic Monitoring and Controlling System for Hydroponics Greenhouse Environments Through Smartphone Application
(2022-01-01)
Channumsin, Orapin
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Trancharoen, Jirasin
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Sonchaiyaphum, Sarut
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Pimpol, Jirapun
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Tangsrirat, Worapong
This article proposes the design and construction of environmental control systems for hydroponics grown vegetables that enable automated control over the environment inside the greenhouse to be most suitable for the plants growth by using microcontroller processing. The systems can track various measurements such as temperature, humidity, intensity of light, water pH value, and water level in a greenhouse by using Blynk application on a smartphone as well as LCD display screen surrounding the greenhouse area. In addition, the systems can automatically control the operation of ventilation fans and mist sprayer machine according to the specified humidity temperature value and it can be set ON and OFF timer for whirlpool pump and LED light bulbs. Moreover, after a 42-day-Testing period of planting three varieties of lettuce, which are Red Oak, Green Oak, and Frillice Iceberg Lettuces, it has been found that Red Oak lettuces have an average width of 21.2 cm, a length of 26.4 cm with a weight of 120 gram, while Green Oak lettuces have an average width of 8.1 cm., a length of 31.0 cm with a weight of 120 gram and lastly, Frillice Iceberg Lettuce has an average width of 19.0 cm, a length of 46.9 cm and a weight of 200 gram.

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