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    Item type:Publication,
    Design of an X-Band CMOS VCO with a Transformer-Coupled and Transconductance-Boosted Stacked Topology
    (2026-06-01)
    Peng, Yen Ying
    ;
    Li, Syu Bin
    ;
    Wang, Sen
    ;
    This paper presents the design and implementation of an X-band voltage-controlled oscillator (VCO) fabricated in a standard 180-nm CMOS process. To sustain stable oscillation under a constrained power budget, a gm-boosted topology is employed, integrating vertically stacked cross-coupled transistors with a center-tapped transformer to enhance the equivalent negative conductance. The boosting is achieved through two complementary mechanisms: the center-tapped transformer performs an impedance transformation that repurposes the layout parasitic capacitances into transconductance-enhancing elements, while the stacked cross-coupled pair reuses the DC current and suppresses the source-degeneration of a conventional pair, jointly sustaining a robust start-up margin at a low 0.75 V supply. On-wafer measurement results demonstrate a frequency tuning range from 8.78 GHz to 9.13 GHz as the control voltage is swept from 0 V to 1.8 V, with an average VCO gain K<inf>VCO</inf> of 447.5 MHz/V. Under a total DC power consumption of 6.9 mW, the oscillator delivers an output power of 4.54 dBm and exhibits a measured phase noise of −103 dBc/Hz at a 1-MHz offset.
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    A 0.3 V Current Differencing Buffered Amplifier and Its Application in Current-Mode Third-Order Low-Pass Filters
    (2025-05-01)
    Khateb, Fabian
    ;
    ;
    Kulej, Tomasz
    This paper introduces an innovative low-voltage, low-power current differencing buffered amplifier (CDBA). The proposed CDBA utilizes a bulk-driven MOS transistor operating in the subthreshold region, allowing it to function effectively at low supply voltages while minimizing power consumption, making it suitable for sensor and biomedical applications. To demonstrate the performance of the proposed CDBA, it is incorporated into the design of a current-mode, third-order low-pass filter that is specifically tailored for bio-sensing applications. Both the CDBA and the low-pass filter are designed and simulated in Cadence Virtuoso using the TSMC 0.18 µm CMOS process. The CDBA operates at a supply voltage of 0.3 V, consuming 170 nW of power, while the third-order low-pass filter achieves a dynamic range of 57.2 dB with a total harmonic distortion (THD) of 1%.
      1
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    0.5-V High-Order Universal Filter for Bio-Signal Processing Applications
    (2025-04-01) ;
    Khateb, Fabian
    ;
    Kulej, Tomasz
    ;
    In this paper, a novel multiple-input operational transconductance amplifier (MI-OTA) is proposed. The MI-OTA can be obtained by using the multiple-input bulk-driven MOS transistor (MIBD MOST) technique. The circuit structure is simple, can operate with a supply voltage of 0.5 V, and consumes 937 pW at a current setting of 625 pA. The proposed MI-OTA was used to implement a high-order multiple-input voltage-mode universal filter. The proposed filter can provide non-inverting and inverting low-pass, high-pass, band-pass, band-stop, and all-pass transfer functions to the same topology. In addition, it has a high input impedance and does not need any inverted input signals, so there is no additional buffering circuit. The proposed filter can be used for biological signal processing. The proposed MI-OTA and the second-order universal filter were simulated in Cadence using CMOS process parameters of 0.18 μm from TSMC to verify the functionality and performance of the new structures.
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    A 38.4 nW, 1.2 V, 250-Hz, 2nd-Order gm - C LPF With Degenerative SCP Transconductors Achieving 800-mVPP Input Range and 82.1- μVrms IRN for ECG Acquisition
    (2025-01-01)
    Thanapitak, Surachoke
    ;
    Pawarangkoon, Prajuab
    ;
    Surakampontorn, Wanlop
    ;
    Ahmad, Rafidah
    ;
    Abdullah Zawawi, Ruhaifi
    In this brief, a 2{^{\text {nd} -order gm - C lowpass filter with a practical input linear range of 400mV P dedicated to ECG signal acquisition is proposed. This filter employs a degenerative source-coupled-pair circuit as a gm cell. It enhances the linear input range by a factor of × 4 compared with the source follower filter. Additionally, to mitigate the effect of current source mismatch, a dynamic element matching technique is applied. By doing so, HD2 is suppressed more than 1.5 dB over the entire passband frequency. This proposed filter is implemented in a 0.18 μ m CMOS process. It offers a 250-Hz bandwidth with input-referred noise and a dynamic range of 82.1 μ Vrms and 67.34 dB, respectively. The power consumption of 38.4 nW is achieved with a 1.2 V supply. Compared with other recent nano-power filters, the proposed filter provides the highest linear input range with competitive Figure-of-Merit to the top-tier designs. It is therefore beneficial to the practical implementation of a low-power ECG acquisition system.
      1
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    Modular Class-AB Current Multiplier Based on Fully-Differential Hyperbolic Transconductor
    (2021-05-26)
    This paper presents a new class-AB current multiplier using fully differential hyperbolic sine transconductors based on floating-gate transistors. The proposed multiplier is developed from a hyperbolic sine multiplication identity which inherently provides a class-AB operation. The proposed multiplier was designed using 0.35 μm AMS CMOS process. Simulation results show that the proposed multiplier achieves -30 dB THD for high input modulation index of 23 while utilizing power consumption of 60 nW under a supply voltage of 3 V.
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    Item type:Publication,
    A low-phase-noise and low-power CMOS colpitts VCO using Gm boosting and capacitance switching techniques
    (2021-01-01) ;
    You, Jia Hao
    ;
    Wang, Sen
    This letter presents a low-power and low-phase-noise 5-GHz VCO fabricated in a standard CMOS 0.18-μm process. The low power dissipation was achieved by using the PMOS cross-coupled pair and G<inf>m</inf>-boosting topology, and the low phase noise was obtained by adding two pairs of switched capacitor array. The VCO consumed a dc power of 2.92 mW with the supply voltage of 1 V. The measured phase noises were − 104.6 dBc/Hz and − 117.4 dBc/Hz at 1 MHz offset frequency with switched off and on capacitances, respectively, which demonstrated 12.8-dB improvement.
      2