On-chip Current Sensor Research Articles

Assessment of On-Chip Current Sensor for Detection of Thermal-Neutron-Induced Transients

This article assesses, for the first time, a body/bulk built-in current sensor (BBICS) in a CMOS 65-nm test chip under thermal neutron, high-energy neutron, and laser radiation. Experimental results suggest that the on-chip current sensor is effective to detect transient faults in different case-study subcircuits of the chip exposed to the accelerated radiation effects, opening prospects for embedding this type of sensor in reliable, secure, and low-power integrated circuit applications.

Two-Input Floating Buck Converter With Variable OFF-Time Control Scheme for High-Efficiency and -Accuracy LED Lighting

A two-input floating buck (TIFB) converter is proposed to decrease voltage stress dramatically, while achieving high power efficiency for LED lighting systems. Its power transistors can also be low voltage and on chip to reduce cost with small chip area. A proposed variable off-time (VOT) control with an on-chip current sensor would detect the peak inductor current and adjust the off-time period dynamically depending on the number of series lighting-emitting diodes (LEDs) and its input voltage. High-accuracy LED current can thus be realized with little additional power. The TIFB converter’s operating principle and the VOT control scheme are described in detail. Experimental results of a prototype in 0.25- $\mu \text{m}$ 5-V CMOS process are shown to verify the theoretical analysis of a proposed LED driver.

A fully integrated switched-capacitor DC–DC converter with hybrid output regulation

In this paper, we propose a fully integrated switched-capacitor (SC) DC–DC converter with hybrid output regulation that allows a predictable switching noise spectrum. The proposed hybrid output regulation method is based on the digital capacitance modulation for fine regulation and the automatic frequency scaling for coarse regulation. The automatic frequency scaler and on-chip current sensor are implemented to adjust the switching frequency at one of the frequencies generated by a binary frequency divider with change in load current. Thus, the switching noise spectrum of the proposed SC DC–DC converter can be predicted over the entire load range. In addition, the bottom-plate losses due to the parasitic capacitances of the flying capacitors and the gate-drive losses due to the gate capacitances of switches are reduced at light load condition since the switching frequency is automatically adjusted. The proposed SC DC–DC converter was implemented in a 0.13 µm CMOS process with 1.5 V devices, and its measurement results show that the peak efficiency and the efficiency at light load condition are 69.2% and higher than 45%, respectively, while maintaining a predictable switching noise spectrum.

Highly efficient current sensor built on a chip based on nanocrystalline NiFe/Cu/NiFe thin film

Abstract We discuss here the realization of a grand vision of a smart GMR device for an on-chip current sensor. The device was characterized to confirm a strong antiferromagnetic coupling and their contribution to giant magnetoresistance. To achieve high sensitivity, we explored different prototypes of device. The GMR sensor is well suited for current sensing as it possesses desired linearity and high sensitivity of 1.32 Ω Oe −1 . The result reveals thickness and number of bilayers play an important role in the magnetization to stay aligned to the current channel. This study brings us a step closer to an ideal on-chip current sensor.

A Low-Distortion High-Efficiency Class-D Audio Amplifier Based on Sliding Mode Control

This brief presents a low-power low-distortion high-efficiency class-D audio amplifier. The proposed architecture uses an integral sliding mode controller with a novel on-chip continuous current sensor. A full-bridge output stage is used to increase the output power, and an adaptive nonoverlapping-clock generation technique is presented to eliminate the short circuit current. Moreover, the switching frequency is chosen to achieve the highest possible linearity without efficiency degradation. The proposed architecture contains the minimum number of loop amplifiers to reduce quiescent current consumption. The proposed class-D audio amplifier has been implemented using 65-nm CMOS technology and operated from a single 2.7-V voltage supply (using thick oxide transistors) while occupying an active area of 0.31 mm 2 . Post-layout simulations show that the proposed architecture achieves a total harmonic distortion of 0.002% for a 2.2 Vpp 1-kHz input signal. It achieves a peak efficiency of 96% and a maximum output power of 400 mW at an 8-Ω differential load.

Adaptive switching frequency buck DC—DC converter with high-accuracy on-chip current sensor**Project supported by the National Natural Science Foundation of China (No. 41274047), the Natural Science Foundation of Jiangsu Province (No. BK2012639), the Science and Technology Enterprises in Jiangsu Province Technology Innovation Fund (No. BC2012121), and the Changzhou Science and Technology Support (Industrial) Project (No. CE20120074).

A current-mode PWM buck DC—DC converter is proposed. With the high-accuracy on-chip current sensor, the switching frequency can be selected automatically according to load requirements. This method improves efficiency and obtains an excellent transient response. The high accuracy of the current sensor is achieved by a simple switch technique without an amplifier. This has the direct benefit of reducing power dissipation and die size. Additionally, a novel soft-start circuit is presented to avoid the inrush current at the starting up state. Finally, this DC—DC converter is fabricated with the 0.5 μm standard CMOS process. The chip occupies 3.38 mm2. The accuracy of the proposed current sensor can achieve 99.5% @ 200 mA. Experimental results show that the peak efficiency is 91.8%. The input voltage ranges from 5 to 18 V, while a 2 A load current can be obtained.

A Fast Response Integrated Current-Sensing Circuit for Peak-Current-Mode Buck Regulator

An on-chip current sensor with fast response time for the peak-current-mode buck regulator is proposed. The initial operating points of the peak current sensor are determined in advance by the valley current level, which is sensed by a valley current sensor. As a result, the proposed current sensor achieves a fast response time of less than 20 ㎱, and a sensing accuracy of over 90%. Applying the proposed current sensor, the peak-current-mode buck regulator for the mobile application is realized with an operating frequency of 2 ㎒, an output voltage of 0.8 V, a maximum load current of 500 ㎃, and a peak efficiency of over 83%.

An On-Chip High-Speed Current Sensor Applied in the Current-Mode DC–DC Converter

A current-mode dc-dc converter with an on-chip current sensor is presented in this letter. The current sensor has significant improvement on the current-sensing speed. The sensing ratio of the current sensor has low sensitivity to the variation of the process, voltage, temperature and loading. The current sensor combines the sensed inductor current signal with the compensation ramp signal and the output of the error amplifier smoothly. The settling time of the current sensor is less than 10 ns. In the current-mode dc-dc converter application, the differential output of the current sensor can be directly sent to the pulse-width modulation comparator. With the proposed current sensor, the dc-dc converter could realize a low duty cycle with a high switching frequency. The dc-dc converter has been fabricated by CSMC 0.5-μm 5-V CMOS process with a die size of 2.25 mm 2. Experimental results show that the current-mode converter can achieve a duty cycle down to 0.11 with a switching frequency up to 4 MHz. The measured transient response time is less than 6 μs as the load current changes between 50 and 600 mA, rapidly.

Combined oscillation and I DDQ testing of a CMOS amplifier circuit

A simple test methodology is presented, combining oscillation and quiescent power supply current (I DDQ) testing for detecting bridging and open faults in a CMOS amplifier circuit formed during fabrication. The testing is performed at room temperature (300 K) and also at liquid-nitrogen temperature (77 K) to enhance fault detection. An on-chip built-in current sensor has been integrated to monitor I DDQ of the circuit under test. A simple fault-injection technique has been used for simulating manufacturing defects. The amplifier was designed for operation at ±2.5 V in a standard 1.5 μm n-well CMOS process. It is shown that all faults can be detected through a combined oscillation and I DDQ testing method. Theoretical results obtained from SPICE simulations are in close agreement with the corresponding experimental results on fabricated devices.

A Monolithic Current-Mode CMOS DC–DC Converter With On-Chip Current-Sensing Technique

A monolithic current-mode CMOS DC-DC converter with integrated power switches and a novel on-chip current sensor for feedback control is presented in this paper. With the proposed accurate on-chip current sensor, the sensed inductor current, combined with the internal ramp signal, can be used for current-mode DC-DC converter feedback control. In addition, no external components and no extra I/O pins are needed for the current-mode controller. The DC-DC converter has been fabricated with a standard 0.6-/spl mu/m CMOS process. The measured absolute error between the sensed signal and the inductor current is less than 4%. Experimental results show that this converter with on-chip current sensor can operate from 300 kHz to 1 MHz with supply voltage from 3 to 5.2 V, which is suitable for single-cell lithium-ion battery supply applications. The output ripple voltage is about 20 mV with a 10-/spl mu/F off-chip capacitor and 4.7-/spl mu/H off-chip inductor. The power efficiency is over 80% for load current from 50 to 450 mA.

Incorporating I_DDQ Testing with BIST forImproved Coverage: An Experimental Study

In this paper we present an experimental study on the effectiveness of incorporating at-speed I_DDQ testing with traditional BIST for improved test coverage. The high speed I_DDQ testing is conducted using the differential built-in on-chip current sensor (BICS) that we have recently developed. Two test chips were designed and fabricated implementing a CMOS version of the 74181 ALU chip. In copies of this circuit we included the capability of activating 45 different “realistic” CMOS faults: inter- and intra-layer shorts and opens. We examine the fault coverage of both Boolean (voltage) testing andI_DDQ testing for these realistic faults. An interesting finding of our study is that I_DDQ testing also detected several of the open faults. Moreover, these include precisely those open faults for which two pattern voltage tests can get invalidated because of transient switching states. Our results show that combining both Boolean and current testing does enhance test coverage in a BIST environment.