Magnetoresistive signal isolators employing linear spin-valve sensing resistors

Abstract

Feasibility of fabricating low power, high-speed, magnetoresistive signal isolators employing linear spin-valve resistors as sensing elements has been demonstrated. In the fabricated prototype digital isolators, linear spin-valve resistors are physically isolated from an on-chip coil by an 11 m BCB isolation barrier, which provides the galvanic isolation with a breakdown voltage larger than 2000 V. The devices are high speed ͑Ͼ50 MHz͒, small size, and low power consumption. Only a 4.5 mA coil driving current is required for the device to be fully functional. The power consumption is estimated to be ϳ1/6 of NVE's present isolator products, which requires a 50 mA coil driving current. Besides digital signal isolators, linear spin-valve resistors can also be used in analog signal isolators. The response of the linear spin-valve resistors to the current passing through the coil has been demonstrated to have a very good linearity, with a linearity error less than 0.05%.

Research progress of giant magnetoresistive isolator

“…Isolator is a kind of input, output and operating power supply isolation from each other, and can realize the signal integrity of the output device, often used for high and low voltage circuit insulation, noise isolation, level matching, ground loop and other application scenarios. Most isolators use optocoupler, capacitor coupler or transformer isolation technology, but these isolation technologies are limited in application areas such as high voltage and high frequency, and in the form of packaging is usually a hybrid package [1] [2]. Optocoupler isolators, as the earliest isolation devices, are also becoming more and more obvious in their disadvantages of large size, slow speed and high energy consumption [3].…”

“…The NVE company then formally developed a commercially available Giant Magnetoresistive Isolator (GMR) in 2000 [12], which can realize multi-channel bi-directional isolation [13], and which has since been brought to the marketplace, with performance limits far exceeding those of photocoupler isolators of the same period. In 2003, Qian Zhenghong et al [1] invented a giant magnetoresistive signal isolator with a linear spin-valve structure using an 11 μm-thick BCB barrier between the giant magnetoresistive sensor and the coil. The barrier can withstand a breakdown voltage of more than 2000 V. The advantages are that the coil drive current of the isolator is only 4.5 mA, the power consumption of the whole isolator structure is 1/6 of the existing isolator products of NVE, and the isolator has a good linearity with a linearity error of less than 0.05%.…”

Temperature relevant performance and calibration of spin-valve sensor

“…The giant magneto-resistance (GMR) effect discovered in 1988 is of importance in academic and technological areas and extensively investigated (Baibich et al , 1988; Binasch et al , 1989; Han et al , 2007; Chen et al , 2012). The spin-valve structure, invented by Dieny et al (1991), is a most widely used GMR material especially in recording read-heads and magnetic sensors because of its high sensitivity and linearity (Kanai et al , 2001; Qian et al , 2004, 2003a, 2003b; Bai et al , 2013; Nakatani et al , 2018). Presently, the spin-valve sensor has been applied as an important component in electronic-compass, current sensor, magnetic isolator, etc (Ueberschär et al , 2015; Ripka, 2010; Kondalkar et al , 2017; Lin et al , 2018; Qian et al , 2011).…”

Effects of Different Relevant Layers on Magnetic Properties of Bottom Synthetic IrMn Spin Valves

“…Since the pioneered work by B. Dieny in 1991 [1], spin valve, a special type of GMR multilayers, has attracted extensive attentions due to its applications in high-sensitivity devices such as read headers and magnetic isolators [2,3]. Spin valve consists of at least four laminated layers: an anti-ferromagnetic (AFM) pinning layer, a ferromagnetic (FM) pinned layer, a nonmagnetic Cu layer and a magnetic free layer (FL).…”