A 5s-time-constant temperature-stable integrator for a tuneable PID controller in LOC applications

Hu, Yuanqi; Liu, Yan; Constandinou, Timothy G.; Toumazou, C.

doi:10.1109/iscas.2011.5937831

Cited by 5 publications

(4 citation statements)

References 12 publications

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“…There is a wide list of techniques in the literature, that makes it possible to achieve transconductances in the range of pA/V. Some examples include, bulk-driven inputs [15,16], drain-driven input [14], current division [17], floating gate structures [17], current steering [18], low-ratio current-mirroring [19], adaptive biasing [20], and Gm cancellation [21]. Most of the above-cited methods are based on a MOS transconductance (gate transconductance, g m , or bulk transconductance, g mb ) to convert the input voltage into a current signal [22].…”

Section: Introductionmentioning

confidence: 99%

A 59 pA/V and 62 nW Differential OTA with 0.35% THD for Biomedical Applications

Silva

Rodovalho

Marques

et al. 2021

JICS

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This paper presents a novel differential pA/V Operational Transconductance Amplifier (OTA) topology. The circuit is suitable for the implementation of fully integrated operational transconductance amplifier-capacitance (OTA-C) filters with small feature size capacitors, suited for electrophysiological signal acquisition and conditioning. Unlike typical OTA-Cs, the proposed topology consists of transconductance reduction technique based on unbalanced output branches thatallow current subtraction thus enabling transconductances in the order of pA/V. The technique is demonstrated through the design of a 59pA/V transconductor, which is very suited for designing long-time-constant filters. This OTA-C achieved a worst-case 0.35% THD with just 61.7nW average power consumption, which allows its applicability to biomedical implants. Simulations were carried out with STMicroelectronics 0.13µm HCMOS9 node using Cadence’s IC design tools. Weemployed the OTA in a design of a fourth-order bandpass filter with a narrow bandwidth of 12.5–21.8Hz. Similar results to the ideal transfer function, turn the proposed OTA ideal for biosensing-based applications.

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Section: Introductionmentioning

confidence: 99%

A 59 pA/V and 62 nW Differential OTA with 0.35% THD for Biomedical Applications

Silva

Rodovalho

Marques

et al. 2021

JICS

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“…To achieve time constants in the above range, large capacitances and low transconductances are needed. Circuit area limits capacitances to ≤1 pF, requiring transconductances on the order of 10 pS [4,5].…”

Section: Introductionmentioning

confidence: 99%

OTA based 200 GΩ resistance on 700 μm2 in 180 nm CMOS for neuromorphic applications

Mayr,

Schultz,

Noack

et al. 2014

Preprint

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Generating an exponential decay function with a time constant on the order of hundreds of milliseconds is a mainstay for neuromorphic circuits. Usually, either subthreshold circuits or RC-decays based on transconductance amplifiers are used. In the latter case, transconductances in the 10 pS range are needed. However, state-of-the-art low-transconductance amplifiers still require too much circuit area to be applicable in neuromorphic circuits where >100 of these time constant circuits may be required on a single chip. We present a silicon verified operational transconductance amplifier that achieves a g m of 5 pS in only 700 µm 2 , a factor of 10-100 less area than current examples. This allows a high-density integration of time constant circuits in target appliations such as synaptic learning or as driving circuit for neuromorphic memristor arrays.

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“…Since the time constants of Gm-C integrators are defined by the ratio C/Gm, reducing Gm allows lower frequencies while using moderated capacitances, and thus smaller die area. A variety of techniques have been proposed and combined in order to push Gm down to pA/V, including floating gate structures, low-ratio current mirroring, Gm-Gm −1 chains, current division [2], and Gm cancellation [3][4][5]. All of the above-mentioned solutions rely on an MOS transconductance (gate transconductance g m or bulk transconductance g mb ) to convert the input voltage into a current signal.…”

mentioning

confidence: 99%

“…Performance figures are summarised and compared with the other large time-constant integrators in Table 2, where the total harmonic distortion (THD) is computed for v in = 0.1V pp . When compared with continuous-time transconductors using complex techniques such as transconductance cancellation [5], current splitting, a g m -attenuated OTA [4], transconductance-transimpedance chaining [3], and even with circuits based on pseudo-resistors [1], the proposed technique allows mHz cutoff frequencies with the smallest reported capacitor.…”

mentioning

confidence: 99%

0.7 pA/V transconductor allowing Gm‐C filters in range of mHz using sub‐pF capacitors

Rodrigues¹,

Silva²

2015

Electron. lett.

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A new topology of a transconductor suitable for the implementation of transconductance-C (Gm-C) integrators with time constants of tens of seconds using sub-pF capacitors is introduced. The proposed circuit relies on a cascode stage driven backwards, i.e. the input signal is applied to the cascode output node. The key point is taking advantage of the high impedance of the cascode to impose high attenuation to the input signal and to establish transconductances in the order of fA/V. The concept is demonstrated at the simulation level by realising a Gm-C integrator with a time constant of 100 s. The integrator comprises a 0.7 pA/V transconductor and an 800 fF capacitor at its output.

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A 5s-time-constant temperature-stable integrator for a tuneable PID controller in LOC applications

Cited by 5 publications

References 12 publications

A 59 pA/V and 62 nW Differential OTA with 0.35% THD for Biomedical Applications

A 59 pA/V and 62 nW Differential OTA with 0.35% THD for Biomedical Applications

OTA based 200 GΩ resistance on 700 μm2 in 180 nm CMOS for neuromorphic applications

0.7 pA/V transconductor allowing Gm‐C filters in range of mHz using sub‐pF capacitors

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