ICsense files new patent on zero-leakage high-voltage analog switches

April 19th, 2018

ICsense, a TDK group company, is a leading supplier of analog, mixed-signal and high-voltage ASICs (Application Specific ICs). The company has filed another patent to strengthen its portfolio in innovative analog circuits. The invention allows to implement analog, floating high-voltage switches that don’t load its connected lines. Contrary to existing solutions using large resistances and thereby large time constants, this invention provides a solution with no leakage current and with a small time constant. It is particularly of interest for low-ohmic (low R_DSon) switch matrix architectures for the medical, automotive, industrial and consumer markets.

High current switch matrix topologies require the use of low-ohmic (D)MOS switches. The desire to have fast switching times (small time constant, small R1) and low leakage (large R1) can not be accomplished with a traditional architecture due to the conflicting requirement on R1 (as shown in Fig 1a). “We have designed a novel circuit to eliminate this conflicting requirement and are able to reach fast switching while having virtually zero-leakage. Moreover, in this classical floating pass-switch design the connected lines are loaded when the switch is enabled/disabled. This results in unwanted and inaccurate readings in applications such as high-impedant, high-voltage multiplexers and high-accuracy, high-voltage readouts like piezo-electrical transceivers” says Tim Piessens, CTO of ICsense.

“We will use this patent to offer ASICs to our customers with increased accuracy and at the same time fast switching and zero-leakage. Our newest patent applies to single MOS switches and to back-to-back topologies that allow full-range isolation,” says Tim. The design is particularly interesting for applications with low R_DSon requirements (<5 Ohm) and heavy constraints on point loading. Additionally, high-voltage switch architectures benefit from the patent because it can cope with negative voltages and polarity changes.

In the past, ICsense has patented other inventions to stay ahead of competition. To produce more cost effective wafers, the company patented a circuit (patent nr BE1024217(A1)) which intelligently regulates stacked transistors to provide higher voltage swing (both drive and sense) in plain CMOS processes. The principle uses complex control techniques to guard the SOA (Safe Operating Area). With this invention it is possible to elevate the operational voltage of a plain low-cost CMOS process¹ by a factor of x4. Since 2010, this patent is exploited in ICs which are in mass production by companies such as NVidia.

¹In a standard 0.18um process, ICsense is able to provide 10V operational swing.
Bert Serneels, Eldert Geukens, Bram De Muer and Tim Piessens, "A 1.5W, 10V Output Class D Amplifier Using a Boosted Supply from a Single 3.3V Input in standard 1.8V / 3.3V 0.18µm CMOS", ISSCC Digest of Technical Papers, Feb 2012.

About TDK Corporation
TDK Corporation is a leading electronics company based in Tokyo, Japan. It was established in 1935 to commercialize ferrite, a key material in electronic and magnetic products. TDK's portfolio includes passive components, such as ceramic, aluminum electrolytic and film capacitors, ferrites and inductors, high-frequency products, and piezo and protection components, as well as sensors and sensor systems and power supplies. These products are marketed under the product brands TDK, EPCOS, InvenSense, Micronas, Tronics and TDK-Lambda. TDK's further main product groups include magnetic application products, energy devices, and flash memory application devices. TDK focuses on demanding markets in the areas of information and communication technology and automotive, industrial and consumer electronics. The company has a network of design and manufacturing locations and sales offices in Asia, Europe, and in North and South America. In fiscal 2017, TDK posted total sales of USD 10.5 billion and employed about 100,000 people worldwide.

About ICsense
ICsense is Europe’s premier IC design company. ICsense’s core business is ASIC development and supply and custom IC design services. ICsense has the largest fab-independent European design group with world-class expertise in analog, digital, mixed-signal and high-voltage IC design. The company develops and supplies customer exclusive ASIC solutions for the automotive (ISO26262), medical (ISO13485), industrial (IEC61508) and consumer (ISO9001) markets. ICsense supplies high-quality, cost-efficient custom ASIC solutions and has built an enviable reputation for tackling first-of-a-kind design projects.

About TDK-Micronas
TDK-Micronas, a TDK group company, is the most preferred partner for sensing and control. TDK-Micronas serves all major automotive electronics customers worldwide, many of them in long-term partnerships for lasting success. Operational headquarters are based in Freiburg (Germany). Currently, the TDK-Micronas Group employs around 900 persons.
For more information about TDK Micronas and its products, please visit www.micronas.tdk.com.

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