Enhanced Single-Stage Folded Cascode OTA Suitable for Large Capacitive Loads

Lopez-Martin, A.J.; Garde, M. Pilar; Algueta, Jose M.; Blas, Carlos A. De La Cruz; Carvajal, R.G.; Ramírez-Angulo, J.

doi:10.1109/tcsii.2017.2700060

Cited by 38 publications

(14 citation statements)

References 18 publications

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“…There are also some reported single‐stage class AB topologies that provide higher FoM L and/or FoM S , but they achieve it at the expense of PM degradation even using large capacitive loads. This is typically because they require increasing the impedance level at internal nodes (eg, using local common‐mode feedback in Lopez‐Martin et al and Pourashraf et al, adaptive loads in Sutula et al, or extra signal paths in Lopez‐Martin et al and Garde et al) which lead to nondominant poles at lower frequencies. This issue may preclude the use of these topologies for small load capacitors without using techniques such as output lead compensation .…”

Section: Simulation and Measurement Resultsmentioning

confidence: 99%

“…First, the input current is sensed at the source of M CN1 ‐M CN2 , in order to benefit from the reduced input resistance at this node due to the FVF feedback loop. Second, the quasi‐floating gate (QFG) technique is applied to achieve class AB operation. It is based on including two capacitors C bat and two high‐resistance pseudo‐resistors M PR .…”

Section: Circuit Descriptionmentioning

confidence: 99%

“…Hence, low quiescent currents can be used in the differential pair, and at the same time large dynamic currents not bounded by the quiescent currents are generated for large input signals, yielding class AB operation. Several class AB amplifiers have been reported with different adaptive biasing techniques, eg . However, the CF/CA is often unchanged, which may limit the power efficiency and dynamic performance of the OTA.…”

Section: Introductionmentioning

confidence: 99%

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Class AB amplifier with enhanced slew rate and GBW

Garde

López-Martín

Algueta

et al. 2019

Circuit Theory & Apps

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The design of a micropower class AB operational transconductance amplifier with large dynamic current to quiescent current ratio is addressed. It is based on a compact and power-efficient adaptive biasing circuit and a class AB current follower using the quasi-floating gate (QFG) technique. The amplifier has been designed and fabricated in a 0.5-μm CMOS process. Simulation and measurement results show a slew rate (SR) improvement factor versus the class A version larger than 4 for the same supply voltage and bias currents, as well as enhanced small-signal performance.

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Section: Simulation and Measurement Resultsmentioning

confidence: 99%

Section: Circuit Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Class AB amplifier with enhanced slew rate and GBW

Garde

López-Martín

Algueta

et al. 2019

Circuit Theory & Apps

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“…Achieving significant gain in advanced CMOS processes is also difficult, and single‐stage cascode structures and two‐stage conventional Miller amplifiers cannot achieve sufficiently high gain for high‐accuracy operation. The alternatives are two‐stage amplifiers with cascoded stages, single‐stage gain‐boosting topologies, multistage Miller amplifiers, and positive feedback structures .…”

Section: Final Remarks and Conclusionmentioning

confidence: 99%

High‐gain, high‐CMRR class AB operational transconductance amplifier based on the flipped voltage follower

Centurelli

Monsurrò

Trifiletti

2019

Circuit Theory & Apps

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Summary A novel class AB operational transconductance amplifier (OTA) topology is proposed, based on a class AB flipped voltage follower. The OTA has class AB behavior, with current boosting both for the load and the compensation capacitors. It has a high gain of (gmr0)4, obtained using a two‐stage structure with cascoded stages, and is a two‐stage Miller‐compensated amplifier employing multipath to remove the positive zero. It has close to rail‐to‐rail output swing (limited by cascoding) and very low common‐mode gain thanks to a replica technique (allowing the use of low‐power common‐mode feedback [CMFB] loops). Ninety‐two decibels of gain and 176 dB of common‐mode rejection ratio (CMRR) without CMFB are achieved using a 40‐nm complementary metal‐oxide semiconductor (CMOS) process. The OTA is used to design a low‐power sample‐and‐hold amplifier (SHA) operating at 5 MSps, a typical application for CMOS OTAs, which has been chosen to verify the proposed circuit's performance and to show that the OTA is robust in Monte Carlo simulations under process variations and mismatches in an actual application.

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“…In this paper, a simple modification to the conventional FC OTA is presented which enhances performance avoiding these issues. A prior version was reported in [7] showing ability to drive in a power efficient manner large capacitive loads. In this paper a modification using lead compensation is proposed which allows preserving a large phase margin for lower capacitive loads.…”

Section: Introductionmentioning

confidence: 99%

Folded Cascode OTA with 5540 MHzpF/mA FoM

Garde

Lopez-Martin

Carvajal

et al. 2018

2018 IEEE International Symposium on Circuits and Systems (ISCAS)

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A micropower single-stage folded cascode amplifier able to drive a wide range of capacitive loads is presented. It features class AB operation and includes power-efficient adaptive biasing techniques, which provide enhanced dynamic output current boosting and gain-bandwidth product (GBW). Phase lead compensation is used to improve phase margin and settling performance for low capacitive loads. Measurement results for a 0.5 μm CMOS process show a FoM of 5540 MHz•pF/mA, the highest one reported to date for a folded cascode amplifier to the authors' knowledge.

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Enhanced Single-Stage Folded Cascode OTA Suitable for Large Capacitive Loads

Cited by 38 publications

References 18 publications

Class AB amplifier with enhanced slew rate and GBW

Class AB amplifier with enhanced slew rate and GBW

High‐gain, high‐CMRR class AB operational transconductance amplifier based on the flipped voltage follower

Folded Cascode OTA with 5540 MHzpF/mA FoM

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