Ladder-Based Synthesis and Design of Low-Frequency Buffer-Based CMOS Filters

Jendernalik, W.; Jakusz, J.; Blakiewicz, Grzegorz

doi:10.3390/electronics10232931

Cited by 3 publications

(5 citation statements)

References 19 publications

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“…The filter presented in this paper can be used to implement low-cost filter banks that emulate the characteristics of the cochlea over the speech frequency range. The proposed filter belongs to the class of buffer-based filters [25] characterized by a DC voltage gain close to unity and an insensitivity to mismatch in the filter passband. Therefore, the proposed filter is suitable for both parallel and cascade banks.…”

Section: Discussionmentioning

confidence: 99%

A 0.5 V Nanowatt Biquadratic Low-Pass Filter with Tunable Quality Factor for Electronic Cochlea Applications

Jakusz,

Jendernalik

2024

Electronics

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A novel implementation of an analogue low-power, second-order, low-pass filter with tunable quality factor (Q) is presented and discussed. The filter feature is a relatively simple, buffer-based, circuit network consisting of eleven transistors operating in a subthreshold region. Q tuning is accomplished by injecting direct current into a network node, which changes the output resistance of the transistors and, as a result, modifies the filter network’s loss, and thus its Q. Q tuning is independent of a filter cut-off frequency (ω0). The filter, with a nominal ω0 of 1 kHz, was fabricated using a 0.18 µm CMOS technology, and features a Q range of 2–11, power consumption of up to 52 nW, and a 59 dB dynamic range when using a 0.5 V supply. The ω0 can be tuned from 0.5 to 2.5 kHz using a traditional method by changing the transistor transconductances, but this process partially affects the quality factor.

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Section: Discussionmentioning

confidence: 99%

A 0.5 V Nanowatt Biquadratic Low-Pass Filter with Tunable Quality Factor for Electronic Cochlea Applications

Jakusz,

Jendernalik

2024

Electronics

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“…All the undefined parameters have their usual meaning. The proposed high-Q filter structure with tunable Q is an extended version of the low-Q and not tunable structure presented in [19].…”

Section: Principle Of Operationmentioning

confidence: 99%

“…The operational transconductance amplifiers (OTAs) are composed of the transistors M 1 -M 4 and 2 × M 0 . The additional transistors M SH1 , M SH2 are DC voltage shifters which improve the operating point conditions for OTAs [19]. All the transistors operate in the saturated subthreshold (weak inversion) region.…”

Section: Transistor-level Circuitmentioning

confidence: 99%

“…The filter capacitances are also assumed to be identical, C1 = C2. By using the floating capacitors (C1/2, C2/2), a twofold reduction in total capacitance and, thus, the area occupied by the filter was achieved [19]. The attenuator consists of transistors M5-M6 and the current source IQ.…”

Section: Transistor-level Circuitmentioning

confidence: 99%

“…This paper proposes a new filter solution well suited to the requirements of an electronic cochlea powered by a small battery or small renewable energy source based on, e.g., thermoelectric generators or electromagnetic energy harvesters. By using a "transistorized" filter structure with transistors operating in the sub-threshold range [19], a significant reduction in voltage and power supply was achieved. As a result of the special tuning method of the filter quality factor and other applied techniques, a high robustness to PVT variations was obtained.…”

Section: Introductionmentioning

confidence: 99%

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Low-Voltage Low-Power Filters with Independent ω0 and Q Tuning for Electronic Cochlea Applications

2022

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An acoustic second-order low-pass filter is proposed for filter banks emulating the operation of a human cochlea. By using a special filter structure and an innovative quality (Q)-factor tuning technique, an independent change of the cutoff frequency (ω0) and the Q-factor with unchanged gain at low frequencies is achieved in this filter. The techniques applied result in a simple filter design with low Q-factor sensitivity to component mismatch. These filter features greatly simplify the implementation of the electronic cochlea in CMOS technologies. An exemplary filter bank designed and simulated in an X-FAB 180 nm CMOS process is presented, which consumes 1.25–34.75 nW of power per individual filter when supplied with 0.5 V. The 11-channel filter bank covers a 20–20 kHz band, while the Q-factor of each channel can be tuned from 2 to 40. The simulation-predicted sensitivities of Q and ω0 to process/voltage/temperature (PVT) variations are less than 1%. The input-referred noise is no greater than 22 µVRMS, and the dynamic range is at least 68 dB for all filters in the bank.

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Fully Tunable Analog Biquadratic Filter for Low-Power Auditory Signal Processing in CMOS Technologies

Jendernalik,

Jakusz

2024

Electronics

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A novel Gm-C structure of a second-order continuous-time filter is proposed that allows for the independent control of the filter’s natural frequency (ω0) and quality factor (Q). The structure consists of two capacitors and four transconductors. Two transconductors together with the capacitors form a lossless second-order circuit with tunable ω0. The other two transconductors form a variable gain amplifier (VGA) which realizes an adjustable loss and thereby adjustable Q. The proposed solution can be used to implement low-voltage and low-power tunable front-end filter banks for fully integrated CMOS cochlear implants and edge intelligence accelerators. An example filter bank powered by 0.5 V and consuming 40 nW of power per single filter is designed and simulated using a 180 nm CMOS process. Circuitries for the adaptive control of transistor bias at a reduced supply voltage are proposed. The ω0 and Q control circuitries are also proposed: a delay-locked loop (DLL)-based system for fine ω0 tuning and a binary-weighted current mirror for Q adjustment. The proposed solution allows for the independent regulation of ω0 and Q within the ranges of 0.25–8 kHz and 1–14, respectively, with a relative tolerance of up to 5% across a filter bank.

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Ladder-Based Synthesis and Design of Low-Frequency Buffer-Based CMOS Filters

Cited by 3 publications

References 19 publications

A 0.5 V Nanowatt Biquadratic Low-Pass Filter with Tunable Quality Factor for Electronic Cochlea Applications

A 0.5 V Nanowatt Biquadratic Low-Pass Filter with Tunable Quality Factor for Electronic Cochlea Applications

Low-Voltage Low-Power Filters with Independent ω0 and Q Tuning for Electronic Cochlea Applications

Fully Tunable Analog Biquadratic Filter for Low-Power Auditory Signal Processing in CMOS Technologies

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