Highly Linear Tunable CMOS $Gm{\hbox{-}}C$Low-Pass Filter

Abstract-A 4 th order Gm-C elliptic low-pass filter with a wide continuous tuning range is presented. The continuous tuning is achieved by means of a new tuning circuit which adjusts the bias current of the Gm cell's input stage to control the cut-off frequency. With this tuning circuit, power efficiency is achieved by scaling down the power consumption proportionally to the cut-off frequency while keeping the linearity near constant over a wide range of frequencies. To extend the tuning range of the filter, Gm switching was employed which also acts on the Gm cell's input stage without adding any switches in the signal path. The filter was fabricated using UMC 180-nm CMOS technology on an active area of 0.23 mm 2 . Its cut-off frequency ranges continuously from 7.4 to 27.4 MHz. This wide range of possible tuning makes the filter suitable for modern wideband GNSS signals in zero-IF receivers. The filter consumes 2.1 and 7.5 mA (from 1.8 V) at its lowest and highest cut-off frequencies, respectively, and achieves a high input IP3 of up to -1.3 dBV RMS .

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“…published CMOS filters [3], [5]- [7]. The values in Table I are reported for the highest cut-off frequency of their respective filters.…”

Section: Measurement Resultsmentioning

confidence: 99%

A wide tuning range 4 <sup>th</sup>-order Gm-C elliptic filter for wideband multi-standards GNSS receivers

Ghamari

Tasselli²,

Botteron

et al. 2015

ESSCIRC Conference 2015 - 41st European Solid-State Circuits Conference (ESSCIRC)

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“…Fig. 2 shows the circuit of linear transconductors used in the filter, which is an implementation of CCIIs [4]. Transistors MN1∼MN10 and MP1∼MP6 of input stage constitute a super source follower.…”

Section: Gm-c Poly-phase Filter Designmentioning

confidence: 99%

A tunable Gm-C polyphase filter with high linearity and automatic frequency calibration

Zhou

Chen

et al. 2014

IEICE Electron. Express

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In this paper, a new CMOS Gm-C poly-phase filter used in Low-IF receiver is presented. As the requirements of multi-model and multi-band determine the frequency tunability, a master-slave transconductance control circuit is designed. Besides, a low power consumption automatic frequency calibrate circuit is used to resist the PVT. A novel 4 th order poly-phase filter is designed in SMIC 0.18 µm standard CMOS process. Consuming 1.1 mA from a 1.8 V voltage, simlution results show that the filter has a tunability of center frequency from 150 kHz to 500 kHz and bandwith from 100 kHz to 900 kHz independently. Meanwhile, the polyphase filter achieves a IIP3 above 18 dBm.

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“…With recent scaling in CMOS technologies use of voltage as control parameter for tuning is becoming increasingly difficult and thus for low voltage OTA applications, tuning is often achieved using bias current as it shows better linear range at low voltages. [1] Tunability provides flexibility to change the range of filters and also the gain in automatic gain controllers. The OTA is known as tunable OTA when the MOSFET using in it operating in saturation or triode regions.…”

Section: Introductionmentioning

confidence: 99%

Voltage-Mode Universal Biquadratic Filter Using Tunable OTA in 180nm Technology

Sahoo¹

2017

IJRASET

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(gm) is an important requirement in many applications such as gm-C active filters, tunable grounded resistors, automatic gain control circuits, etc. Transconductance tuning is required not only to compensate for fabrication tolerances but also to achieve programmability of relevant parameters. Tuning in operational transconductance amplifier (OTA) is achieved by either varying transconductance as function of control voltage or bias current. With recent scaling in CMOS technologies use of voltage as control parameter for tuning is becoming increasingly difficult and thus for low voltage OTA applications, tuning is often achieved using bias current as it shows better linear range at low voltages.[1] Tunability provides flexibility to change the range of filters and also the gain in automatic gain controllers. The OTA is known as tunable OTA when the MOSFET using in it operating in saturation or triode regions. If we change the control voltage or the bias current, then the transconductance will be varied. Because of linearity restrictions, the circuits which use voltage as control parameter to change the OTA transconductance will have limited range of operation at low voltage. OTA transconductance can also be made vary by changing the bias current. [6] [7]

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Highly Linear Tunable CMOS $Gm{\hbox{-}}C$Low-Pass Filter

Cited by 61 publications

References 27 publications

A wide tuning range 4 <sup>th</sup>-order Gm-C elliptic filter for wideband multi-standards GNSS receivers

A wide tuning range 4 <sup>th</sup>-order Gm-C elliptic filter for wideband multi-standards GNSS receivers

A tunable Gm-C polyphase filter with high linearity and automatic frequency calibration

Voltage-Mode Universal Biquadratic Filter Using Tunable OTA in 180nm Technology

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