18.3 An Auto-Zero Stabilized Voltage Buffer with a Quiet Chopping Scheme and Constant Input Current

Rooijers, Thije; Huijsing, Johan H.; Makinwa, Kofi A. A.

doi:10.1109/isscc.2019.8662437

Cited by 7 publications

(12 citation statements)

References 3 publications

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“…The main switches are driven by capacitively-coupled constant-VGS drive circuits (Fig. 4), which effectively add a fraction of a 1.8V clock signal to a buffered version of Vin [5]. The amplitude of the resulting clock signal Φ1,2_bo is determined by the ratio of the boosting capacitor (CB1-B2) to the parasitic capacitance to ground (CP1-P2).…”

Section: Input Current Trimming Schemementioning

confidence: 99%

“…Furthermore, it also causes output spikes, making it more difficult to interface such amplifiers with subsequent circuitry. Recently, an auto-zero (AZ) stabilized buffer has been proposed [4,5]. As shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…This design achieves state-of-the-art offset (< 1µV) and low-frequency noise performance (only √2× higher than the buffer's own thermal noise floor). However, the charge injection of its input switches gives rise to significant input current: up to 0.8pA [5]. Since this current is relatively independent of input voltage, however, it can be effectively trimmed at a single input voltage.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, even after trimming, its input current is still quite high (90pA). Since the architecture of the proposed AZ stabilized buffer ensures that it produces no measurable switching artefacts [4,5], its input switches can be switched at a much lower frequency (fAZ = 15kHz). This, in turn, results in much lower input current (0.2pA) after trimming.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

An Auto-Zero Stabilized Voltage Buffer with a Trimmed Input Current of 0.2pA

Rooijers

Huijsing

Makinwa

2019

ESSCIRC 2019 - IEEE 45th European Solid State Circuits Conference (ESSCIRC)

Self Cite

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Section: Input Current Trimming Schemementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An Auto-Zero Stabilized Voltage Buffer with a Trimmed Input Current of 0.2pA

Rooijers

Huijsing

Makinwa

2019

ESSCIRC 2019 - IEEE 45th European Solid State Circuits Conference (ESSCIRC)

Self Cite

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“…These methods are divided into two categories. One is the dynamic offset cancellation (DOC) technique, such as auto-zeroing [17]- [20], [30] and chopper [14], [21]- [23]. Auto-zeroing uses sampling-elimination technology to eliminate the offset voltage while the chopper uses high frequency modulation followed by bandwidth filter to decrease the offset voltage.…”

Section: Introductionmentioning

confidence: 99%

A High Accuracy Weak Voltage LED Analog Dimming Method

Zhang

Gao

et al. 2019

IEEE Access

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A weak voltage analog dimming method for high precision light emitting diode (LED) current control with N-Bits analog static offset calibration (N-Bits ASOC), dynamic offset cancellation (DOC) and K-times dimming duty to voltage (KD2V) conversion is presented. The N-Bits ASOC circuit decreases the analog dimming error to V OSMAX /2 N − 1 by pre-calibrating the error amplifier offset. Moreover, through a smart combination of KD2V circuits and DOC amplifier, the KD2V and DOC operational amplifier magnify the dimming reference and LED current sense voltage K-times, respectively, which reduces the residual dimming error K-times without any modification to the LED current sampling resistor. Based on the 0.18µm 5V/40V Bipolar-CMOS-DMOS (BCD) process, experimental results for a cell phone backlighting driver show that the analog dimming I LED error reduces to 30µA at maximum 200mV LED current feedback voltage. This deviation mostly keeps constant through a dimming duty range of 0.5% to 100% and V IN range of 2.7V to 5.5V. Furthermore, a 200-sample measurement data suggests that this method is effective even when dimming duty is smaller than 0.5% for mass production.INDEX TERMS LED analog dimming, pulse width modulation (PWM) dimming, dynamic offset cancellation (DOC), analog static offset calibration (ASOC).

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Low-Noise Chopper-Stabilized Zero-Drift Amplifier With SAR-Assisted Automatic Offset Calibration Loop

Nam,

Choi,

Yoo

et al. 2023

IEEE Access

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This paper presents a low-noise chopper-stabilized zero-drift amplifier with successive approximation register (SAR)-assisted automatic offset calibration loop (AOCL). The amplifier is designed using multipath zero-drift architecture including a low frequency path (LFP) and a high frequency path (HFP). The multipath architecture can achieve the low offset, the low noise and the low drift while maintaining the wide bandwidth. The LFP amplifier exploits a chopper scheme to reduce the offset and the low-frequency noise components. The digitally assisted AOCLs in the LFP and the HFP using SAR and current-mode digital-to-analog converter (DAC) can reduce the offset coarsely. The mismatch and the offset of the LFP amplifier can generate the up-modulated output ripples. The residual ripples in the LFP can be reduced using a ripple reduction loop (RRL). To prevent secondary ripple caused by the offset of the RRL itself, an autozero (AZ) integrator is employed. The HFP amplifier is designed using the folded-cascode structure with class-AB output stage to enhance the power efficiency. The multipath amplifier is fabricated in a 0.18 μm CMOS process. The current consumption, supply voltage and active area are 130 μA, 1.8 V and 0.86 mm 2 , respectively. The amplifier has a unit gain bandwidth (UGBW) of 0.875 MHz, an input referred offset of 4.6 μV, an input referred noise of 25.6 nV/√Hz, an offset drift of 53 nV/℃ and a noise efficiency factor (NEF) of 11.2.INDEX TERMS Multipath amplifier, ripple reduction, automatic offset calibration loop (AOCL), SAR.

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18.3 An Auto-Zero Stabilized Voltage Buffer with a Quiet Chopping Scheme and Constant Input Current

Cited by 7 publications

References 3 publications

An Auto-Zero Stabilized Voltage Buffer with a Trimmed Input Current of 0.2pA

An Auto-Zero Stabilized Voltage Buffer with a Trimmed Input Current of 0.2pA

A High Accuracy Weak Voltage LED Analog Dimming Method

Low-Noise Chopper-Stabilized Zero-Drift Amplifier With SAR-Assisted Automatic Offset Calibration Loop

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