A CMOS Active-<i>RC</i> Low-Pass Filter With Simultaneously Tunable High- and Low-Cutoff Frequencies for IEEE 802.22 Applications

Shin, Hyunchol; Kim, Young-Cho

doi:10.1109/tcsii.2009.2037994

Cited by 32 publications

(3 citation statements)

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“…As shown in the figure, the complex BPF comprises two biquads in the I and Q paths that are cross-connected by two cross-coupling resistors R xa and R xb . The biquad is based on a two-integrator-loop Tow-Thomas structure, which is widely adopted for baseband LPF designs [14,15]. The biquad in Figure 2 is known as an inverted Tow-Thomas structure since its lossless integrator part is placed before the lossy integrator part [16].…”

Section: Circuit Designmentioning

confidence: 99%

“…The LPF has a cutoff frequency fc = 1/(2πC 1 R 2 ), quality factor Q = R 3 /R 2 , and gain Av = R 2 /R 1 . As indicated in Figure 2, the passive components R 1 , R 3 , and C 1 are designed in a switched array form so that their values can be digitally tuned [14]. R 2 is set to a fixed value because changes in this value lead to simultaneous changes of the cutoff frequency, quality factor, and gain.…”

Section: Circuit Designmentioning

confidence: 99%

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Low-Power CMOS Complex Bandpass Filter with Passband Flatness Tunability

et al. 2020

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We present a low-power CMOS active-resistance-capacitance (active-RC) complex bandpass filter (BPF) with tunable gain, bandwidth, center frequency, quality factor, and passband flatness for Bluetooth applications. A transfer function analysis for a cross-coupled Tow-Thomas biquad structure is presented to prove that the flatness profile of the passband gain can be effectively controlled by independently tuning two cross-coupling resistors. The proposed biquad-based complex BPF was employed to realize a fourth-order baseband analog processor for a low intermediate frequency (low-IF) RF receiver. The baseband analog processor was composed of two complex biquad filters and three first-order variable-gain amplifiers. It was fabricated in a 65-nm RF CMOS and achieved wide tuning capabilities, such as a gain of −15.6 to 50.6 dB, a bandwidth of 1.4–3.9 MHz, a center frequency of 1.5–4.1 MHz, and a passband flatness of −1 to 1 dB. It also achieved an image rejection ratio of 40.3–53.3 dB across the entire gain tuning range. It consumed 1.4 mA from a 1 V supply and occupied an area of 0.19 mm2 on the silicon substrate. The implementation results prove that the proposed complex BPF was able to effectively enhance the signal processing performances through the flexible and wide-range tunability of the passband flatness, as well as that of the gain, bandwidth, center frequency, and quality factor.

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Section: Circuit Designmentioning

confidence: 99%

Section: Circuit Designmentioning

confidence: 99%

Low-Power CMOS Complex Bandpass Filter with Passband Flatness Tunability

et al. 2020

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“…LPF is considered to remove unwanted components and establish the Nyquist theory. Topologies of continuous-time (CT) LPF can be classified into two main structures; active RC, 10 and transconductance-C (G m -C). 11,12 The cutoff frequency in the active RC filter is equal to 1/2πRC.…”

Section: Introductionmentioning

confidence: 99%

A low power‐area low pass G_m‐C filter in biomedical analog front end for biosignal acquisition

Vafaei,

Parhizgar,

Abiri

et al. 2023

Circuit Theory & Apps

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SummaryIn this paper, a low‐power transconductor‐capacitor (Gm‐C) filter with programmable cutoff frequency is designed for electroencephalogram (EEG), electrocardiogram (ECG), and surface electromyography (sEMG) biosignals. The second‐order Butterworth low pass filter (LPF) is designed as an interface between an instrumentation amplifier (IA) and an analog‐to‐digital converter (ADC). The proposed Gm‐C filter suppresses out‐of‐band components and also plays an anti‐aliasing role. With the variable transconductance based on flipped voltage follower (FVF), the cutoff frequencies of 100 Hz, 560 Hz, and 1.5 kHz are obtained for EEG, ECG, and sEMG, respectively. This structure is highly accurate by using a robust and low‐power common mode feedback (CMFB). With 0.8 V supply voltage, the total power consumption of the filter is only 56 nW, 100 nW, and 221 nW for cutoff frequencies of 100 Hz, 560 Hz, and 1.5 kHz, respectively. The proposed Gm‐C filter is simulated in TSMC 65 nm CMOS technology and occupies an area of 0.12 mm2. The figure of merit (FOM) of the proposed filter is equal to 1.9 pW/pole.

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All MOSCAP Based Continuously Tunable Filter

Palani

Harjani

2016

Analog Circuits and Signal Processing

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A CMOS Active-RC Low-Pass Filter With Simultaneously Tunable High- and Low-Cutoff Frequencies for IEEE 802.22 Applications

Cited by 32 publications

References 8 publications

Low-Power CMOS Complex Bandpass Filter with Passband Flatness Tunability

Low-Power CMOS Complex Bandpass Filter with Passband Flatness Tunability

A low power‐area low pass G_m‐C filter in biomedical analog front end for biosignal acquisition

All MOSCAP Based Continuously Tunable Filter

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A CMOS Active-RC Low-Pass Filter With Simultaneously Tunable High- and Low-Cutoff Frequencies for IEEE 802.22 Applications

Cited by 32 publications

References 8 publications

Low-Power CMOS Complex Bandpass Filter with Passband Flatness Tunability

Low-Power CMOS Complex Bandpass Filter with Passband Flatness Tunability

A low power‐area low pass Gm‐C filter in biomedical analog front end for biosignal acquisition

All MOSCAP Based Continuously Tunable Filter

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Product

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A low power‐area low pass G_m‐C filter in biomedical analog front end for biosignal acquisition