Browsing by Author "Maundy, Brent JP"

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    All-Pass Delays and Residue Amplifier for a 10-GS/s Non-Blocking Subranging ADC
    (2025-01-08) Kabirkhoo, Zahra; Belostotski, Leonid; Maundy, Brent JP; Murari, Kartikeya
    Delay circuits play a critical role in various applications, notably, in recent years, analog delays have been utilized in certain analog-to-digital converter (ADC) architectures, including continuous-time pipelined ADCs (CTP-ADCs) and non-blocking subranging ADCs (NBSADCs), where they help improve the overall ADC speed and/or resolution. In this work, the proposed delay circuits are specifically tailored for a 10-GS/s, 8-bit non-blocking subranging ADC (NBS-ADC) intended for radio telescope applications. First, this thesis proposes a high-order all-pass-filter (APF) circuit topology. The design process and tunability are explored using both TSMC 65-nm-CMOS and 22-nm FDSOI CMOS technologies. The proposed 6th-order APF, implemented in TSMC 65-nm-CMOS, achieves a delay range from 250 ps (BW10%=0–8 GHz) to 400ps (BW10%=0–5 GHz) having the state-of-the-art DBW10%=2. Additionally, 3rd- and 4th-order APFs were subsequently designed in GlobalFoundries 22-nm FDSOI CMOS for a 5G beamforming receiver operating from 24.3 to 28.7 GHz. The 3rd- and 4th-order APFs exhibited 9-to-21 and 21-to-36 ps delay ranges, respectively, to generate beams from 0° to 35°. Also, in further steps we sought a solution to eliminate inductors entirely, leading to the design of a compact, inductorless, cascadable GHz-frequency APF delay circuit. Results obtained using a TSMC 65-nm-CMOS containing 4 cascaded APF cells, exhibiting a delay tuning range of 300 to 500 ps over a 0.1-to-4-GHz bandwidth. The filter occupies an active area of 0.04 mm2 and dissipates 6.2 mW/cell from a 1.3-V supply. The APF achieved a delay-per-area metric that is at least 1.6 times greater than that of previous gm-C APFs, while also operating across a wider bandwidth. It exhibited a high delay-bandwidth product (DBW) of 1.95, all while maintaining a gain of 3.3 dB. Finally, we presented a novel residue generation and amplification (RGA) stage that employs inductive peaking and a tunable-gain post-amplifier reaching a high gain and a wide bandwidth, for a 10-GS/s, 8-bit NBS-ADC intended for radio telescope applications.
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    Design and Implementation of Single Transistor Active Filters
    (2017) Poddar, Neethila Nabanita; Maundy, Brent JP; Murari, Kartikeya; Lachapelle, Gerard Jules
    This thesis investigates the design of single transistor second order active filters. Four general topologies are presented, each with a two port network surrounded by three impedances that form a T-network. From the topologies, four transfer functions are derived which are further simplified by replacing the two port transmission matrix parameters with those of an ideal MOS. An exhaustive MAPLE search code is used to generate all possible second order filters. The search is carried out on the four general transfer functions, considering all possible impedance combinations. Design procedures of selected filters are shown and verified by Cadence Spectre simulations and experimental measurements. Based on the single transistor second order filters, active realizations of higher order filters are explored. A fourth order bandpass Chebyshev filter and a fourth order Comb filter are presented. Simulation and experimental results of the designed filters are shown and compared with the theoretical ones.