Stability analysis of fully-differential active-RC filters with common-mode feedback network

A simple scheme to implement class AB low-voltage fully differential amplifiers that do not require an output common-mode feedback network (CMFN) is introduced. It has a rail to rail output signal swing and high rejection of common-mode input signals. It operates in strong inversion with ±300 mV supplies in a 180 nm CMOS process. It uses an auxiliary amplifier that minimizes supply requirements by setting the op-amp input terminals very close to one of the rails and also serves as a common-mode feedback network to generate complementary output signals. The scheme is verified with simulation results of an amplifier that consumes 25 µW, has a gain-bandwidth product (GBW) of 16.1 MHz, slew rate (SR) of 8.4 V/µs, the small signal figure of merit (FOMSS) of 6.49 MHz*pF/µW, the large signal figure of merit (FOMLS) of 3.39 V/µs*pF/µW, and current efficiency (CE) of 2.03 in strong inversion, with a 10 pF load capacitance.

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Selection of the common-mode feedback network connection of fully differential Gm-C filters

IET Circuits Devices & Systems ◽

10.1049/iet-cds:20080225 ◽

2009 ◽

Vol 3 (1) ◽

pp. 49-56 ◽

Cited By ~ 2

Author(s):

J. Mahattanakul ◽

W. Surakampontorn ◽

P. Khumsat

Keyword(s):

Common Mode ◽

Fully Differential ◽

Network Connection ◽

Feedback Network ◽

The Common ◽

Selection Of

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Improved loop stability approach in fully differential operational transconductance amplifier with common‐mode feedback circuit

International Journal of Circuit Theory and Applications ◽

10.1002/cta.3218 ◽

2022 ◽

Author(s):

Reza Daie Koozehkanani ◽

Somaye Makouei ◽

Siroos Toofan

Keyword(s):

Feedback Circuit ◽

Operational Transconductance Amplifier ◽

Common Mode ◽

Fully Differential ◽

Transconductance Amplifier ◽

Loop Stability

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Fully Differential Class-AB OTA with Improved CMRR

Journal of Circuits System and Computers ◽

10.1142/s0218126617501699 ◽

2017 ◽

Vol 26 (11) ◽

pp. 1750169 ◽

Cited By ~ 1

Author(s):

Francesco Centurelli ◽

Pietro Monsurrò ◽

Gaetano Parisi ◽

Pasquale Tommasino ◽

Alessandro Trifiletti

Keyword(s):

Cmos Technology ◽

Current Mirror ◽

Differential Mode ◽

Common Mode ◽

Common Mode Rejection Ratio ◽

Class Ab ◽

Fully Differential ◽

Rejection Ratio ◽

Mode Behavior ◽

The Common

This paper presents a fully differential class-AB current mirror OTA that improves the common-mode behavior of a topology that presents very good differential-mode performance but poor common-mode rejection ratio (CMRR). The proposed solution requires a low-current auxiliary circuit driven by the input signal, to compensate the effect of the common-mode input component. Simulations in 40-nm CMOS technology show a net reduction of common-mode gain of more than 90[Formula: see text]dB without affecting the differential-mode behavior; a sample-and-hold amplifier exploiting the proposed amplifier has also been simulated.

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Design of a New Low Power Fully Differential Amplifier with Settling Time Enhancement Characteristics

Journal of Circuits System and Computers ◽

10.1142/s0218126615500784 ◽

2015 ◽

Vol 24 (06) ◽

pp. 1550078 ◽

Cited By ~ 1

Author(s):

Seid Jafar Hosseinipouya ◽

Farhad Dastadast

Keyword(s):

High Performance ◽

Settling Time ◽

Cmos Process ◽

Output Stage ◽

Common Mode ◽

Class Ab ◽

Fully Differential ◽

Op Amp ◽

Transconductance Amplifier ◽

Adaptive Biasing

High performance of fully differential operational transconductance amplifier is designed and implemented using a 0.18-μm CMOS process. The implemented op-amp uses common mode feedback (CMFB) circuit operating in weak inversion region which does not affect other electrical characteristics due to eliminating common mode (CM) levels automatically leading to improve CM rejection ratio (CMRR) of the amplifier significantly. Moreover, the output stage has class-AB operation so that its current can be made larger due to increasing the output current dynamically using adaptive biasing circuit. Additionally, the AC currents of the active loads have been significantly reduced using negative impedances to increase the gain of the amplifier. The results show the GBW 2.3 MHz, slew rate 2.6 V/μs and 1% settling time 150 ns with a capacitive load of 15 pF. This amplifier dissipates only 6.2 μW from a 1.2 V power supply.

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