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A Simplified Analog Implementation of Cyclic Shift Chirp Encoding and Decoding for LoRa Communications
(2026-06-01)
Saelim, Nopparut
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Tuwanut, Panwit
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Pornavalai, Chotipat
Currently, LoRa wireless communication technology has become widely adopted in IoT systems due to its long-range capability and low power consumption. However, LoRa is a technology developed by Semtech, which does not disclose the details of the Cyclic Shift Chirp encoding process, a core component of LoRa signals. This lack of transparency prevents users from accessing the physical-layer structure of the signal or freely customizing key parameters such as bandwidth and spreading factor. Although such customization can enhance system flexibility, there is currently no officially disclosed method to achieve it. This research proposes a Cyclic Shift Chirp encoder/decoder circuit built from basic analog components, including adders, subtractors, comparators, and ramp generators, based on a Pulse Width Modulation (PWM) principle. This approach enables researchers and developers to generate LoRa-like signals independently and customize various parameters without introducing limitations. Moreover, the proposed circuit is simple, low-cost, and easy to understand, making it suitable for advanced research, educational experiments, and the design of communication systems that require high flexibility at the LoRa PHY layer.
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Single Commercially Available Integrated Circuit-based Sinusoidal Oscillators with Amplitude Adjustability and Electronic Control of Condition
(2024-09-01)
Duangkaew, Suleeporn
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Supavarasuwat, Piya
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Siripruchyanun, Montree
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Sotner, Roman
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Jaikla, Winai
This paper presents four new sinusoidal oscillators using a commercially available integrated circuit (IC). The proposed circuits are simple topologies that employ a single commercial IC, LT1228. It is connected to passive element, consisting of four resistors and two capacitors. All derived oscillator circuits have low output impedance, allowing them to connect to other circuits without requiring an additional buffer. Using an active LT1228 device enables electronic adjustment of parameters in the proposed circuits. A feedback resistor can be used to change the output signal's amplitude without affecting the oscillation's frequency or condition. We performed both simulations using the PSPICE program and experiments to confirm the accuracy of all proposed oscillator circuits. The best total harmonic distortion was 0.13% for the proposed oscillator circuit 3. Adjusting the maximum amplitude using a resistor provides a gain of roughly 1.5–16.5 dB for the proposed oscillator circuit no. 1.
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Current-Mode Active Filter Using EX-CCCII
(2024-06-01)
Kumngern, Montree
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Khateb, Fabian
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Kulej, Tomasz
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Tooprakai, Siraphop
This paper presents a novel multiple-input and multiple-output current-mode universal analog filter with electronic tuning capability. The proposed circuit uses a single second-generation current-controlled current conveyor with extra-X terminals (EX-CCCII) and two grounded capacitors. The filter can offer five standard filtering functions, namely low-pass, high-pass, band-pass, band-stop, all-pass responses, in the same circuit without changing the internal configuration of the filter by selecting appropriate input and output signals. To obtain the five standard filtering functions, inverted input signal and input matching conditions are absent. The natural frequency of all filter responses can be electronically controlled. The proposed circuit was simulated by SPICE using 0.18 μm CMOS process from Taiwan Semiconductor Manufacturing Company (TSMC). The results of experiments using the integrated circuit operational amplifier AD844 confirm the functionality of the new filter.
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Gain-Controllable Transadmittance-Mode First-Order Allpass Filters with Electronic Tune Using Single Active Element
(2024-02-01)
Tanaphatsiri, Chaiya
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Khateb, Fabian
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Sotner, Roman
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Jaikla, Winai
First-order allpass filters are analog filters with a unit magnitude response, but they change the phase shift between input and output signals at various frequencies. This paper presents the transadmittance-mode first-order allpass filters based on the modified current-controlled current differencing transconductance amplifier (M-CCCDTA). The proposed filters utilize a single M-CCCDTA and a grounded capacitor with no external resistors, making them well suited for implementation in an integrated circuit. The gain and phase response of the proposed filters can be adjusted electronically and separately. Also, the high output impedance of the proposed filters at both the input voltage node and the output current node makes cascading easy without the need for buffer devices. A quadrature sinusoidal oscillator based on the proposed first-order allpass filter has been designed as an example of an application. The PSpice simulation and actual experiments are utilized to validate the functionality of the proposed filters. The simulation and experimental results are consistent with the idea of anticipation.
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Low-Voltage Mixed-Mode Analog Filter Using Multiple-Input Multiple-Output Operational Transconductance Amplifiers
(2024-01-01)
Kumngern, Montree
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Khateb, Fabian
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Kulej, Tomasz
This paper presents a novel mixed-mode, low-power, 1 V analog filter that uses multiple-input multiple-output operational transconductance amplifiers (MIMO-OTAs). This filter uses four OTAs, two grounded capacitors, and one grounded resistor and offers four modes, namely voltage, current, transconductance, and transimpedance modes. Each mode of operation provides non-inverting and inverting low-pass, high-pass, band-pass, band-stop, and all-pass filter transfer functions (10 transfer functions). Thus, in four operating modes, the designed filter offers 40 transfer functions, which is the full capability of a mixed universal filter. The natural frequency of all filter functions can be electronically controlled. To obtain the multi-input OTA, the multiple-input bulk-driven MOS transistor (MIBD-MOST) technique is used. This technique can reduce the number of MOS input differential pairs and the supply voltage. The active mixed-mode filter was simulated using a CMOS TSMC 0.18μ m process in the Cadence Virtuoso ADE Suite. The simulation results confirm the performance of the proposed filter.
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0.5-V Nano-Power Shadow Sinusoidal Oscillator Using Bulk-Driven Multiple-Input Operational Transconductance Amplifier
(2023-02-01)
Khateb, Fabian
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Kumngern, Montree
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Kulej, Tomasz
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Yavari, Mohammad
This paper presents a low-frequency shadow sinusoidal oscillator using a bulk-driven multiple-input operational transconductance amplifier (MI-OTA) with extremely low-voltage supply and nano-power consumption. The proposed oscillator is composed using two-input single-output biquad filter and amplifiers. The condition and the frequency of oscillation of the shadow oscillator can be controlled electronically and independently using amplifiers. The circuit is designed in Cadence program using 0.18 µm CMOS technology from TSMC. The voltage supply is 0.5 V and the power consumption of the oscillator is 54 nW. The total harmonic distortion (THD) of the output signals is around 0.3% for 202 Hz. The simulation results are in accordance with theory.
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0.5 V Versatile Voltage- and Transconductance-Mode Analog Filter Using Differential Difference Transconductance Amplifier
(2023-01-01)
Kulej, Tomasz
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Kumngern, Montree
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Khateb, Fabian
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Arbet, Daniel
In this work, a new versatile voltage- and transconductance-mode analog filter is proposed. The filter, without requiring resistors, employs three differential-difference transconductance amplifiers (DDTAs) and two grounded capacitors, which is suitable for integrated circuit implementation. Unlike previous works, the proposed filter topology provides: (1) high-input and low-output impedances for a voltage-mode (VM) analog filter, that is desirable in a cascade method of realizing higher order filters, and (2) high-input and high-output impedances for a transconductance-mode (TM) analog filter without any circuit modification. Moreover, a quadrature oscillator is obtained by simply adding a feedback connection. Both VM and TM filters provide five standard filtering responses such as low-pass, high-pass, band-pass, band-stop and all-pass responses into single topology. The natural frequency and the condition of oscillation can be electronically controlled. The circuit operates with 0.5 V supply voltage. It was designed and simulated in the Cadence program using 0.18 µm CMOS technology from TSMC.
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0.5-V Nano-Power Voltage-Mode First-Order Universal Filter Based on Multiple-Input OTA
(2023-01-01)
Khateb, Fabian
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Kumngern, Montree
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Kulej, Tomasz
This paper presents a new application of the multiple-input operational transconductance amplifier (MI-OTA). The MI-OTA has been used to realize a first-order universal filter which shows that the first-order transfer functions such as low-pass, high-pass, and all-pass filters can be obtained easily from a single topology by applying the input signal to the appropriate terminals. Moreover, both non-inverting and inverting transfer functions of all filtering functions can be obtained. The pole frequency of all filters can also be controlled electronically. The first-order all-pass filters have been selected to realize high-quality band-pass filter. For low-voltage supply operation and extremely low power consumption, the proposed MI-OTA is realized by the multiple-input bulk-driven MOS transistor technique with transistors operating in subthreshold voltage region. The circuit has been simulated using the 0.18 μ m TSMC CMOS technology with 0.5 V of supply voltage and it consumes 29.77 nW of power for 10 nA nominal setting current. The post-layout simulation results show that the applications of MI-OTA agree well with theory.
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Current-Mode Universal First-Order Analog Filter Using CCCIIs
(2023-01-01)
Phatsornsiri, Punnavich
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Torteanchai, Usa
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Wongprommoon, Natapong
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Kumngern, Montree
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Jongchanachavawat, Wirote
This paper presents a new current-mode first-order universal analog filter using current-controlled current conveyors (CCCIIs). The proposed circuit can realize first-order sections such as all-pass, low-pass, high-pass filters with both non-inverting and inverting transfer functions into single topology. The pole frequency of these filters can be controlled electronically. The output terminals possess high impedance level which is required for cascading of current-mode circuits. The proposed analog filter is verified using SPICE simulation. The CCCII has been simulated using the 0.18 µm CMOS technology with a supply voltage of 1.8 V. The simulation result can show that it agrees well with theory.
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Boosting the Quality Factor of the Shadow Bandpass Filter
(2022-09-30)
Buakaew, Seangrawee
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Wongtaychatham, Chariya
This paper proposes a new method to increase the quality factor of the shadow bandpass filter. The proposed circuit topology is simple, with the use of conventional biquad cell along with external amplifiers. The major advantageous feature is that the quality factor of the filter is boosted up whereas the gain of the external amplifier is significantly reduced. Moreover, the presented idea can be applied to the shadow filter in both current and voltage modes. The proposed scheme is justified via circuit performance. The performance is compared with the previous research works in the same arena. The results show that a feedback signal and a properly chosen gain incredibly boost up the quality factor of the shadow bandpass filter. Simulations by PSpice using 0.18-μm CMOS-level parameters confirm the validity of the proposed work.

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