AMS uses 3D chip technology for smartphone sensors

Austrian chip maker ams is applying through-silicon via (TSV) 3D IC fabrication technology to its ambient light sensor devices.

TSV technology is being used to interconnect stacked wafers in FPGAs and memory chips and ams believes it can apply the technology to analogue sensors to very small wafer scale packages.

“We have been developing the TSV capability and expect to be in production with first sensors in the middle of the year,” said Thomas Riener, senior v-p marketing communications at ams.

The company is planning to develop more highly integrated and smaller ambient light sensors for use in smartphones and cameras.

After the acquisition of US-based light sensor firm TAOS in 2011, supplying sensors to smartphone manufacturers has become an important business for the Graz-based manufacturer.

“We have 40% market share in ambient light sensors in smartphones, “claimed Riener.

As a result the firm has doubled revenues in the last three years and sensor devices, standard products and Asics, make up 70% of sales for ams.

The mixed-signal company has also developed NFC and RFID “signal booster” devices for use in smartphones.

“These will be revenue driver this year and beyond, we already have a high number of design-ins,” said Riener.

The company also supplies an interface chip to MEMS microphone supplier Knowles. “

The company designs chip in the US and Europe, but all manufacturing is in Austria.

“Manufacturing is very important for us and we believe in retaining all critical production technologies,” said Riener.

“We believe analogue chip production is critical to Europe and the engineering talent is here,” said Riener.

Also important to ams is a new power management IC (PMIC) it originally designed as an Asic for Nvidia for its Tegra smartphone processor.

It has devised a novel two-wire remote-feedback circuit between processor and DC-DC controller.

The use of a simple two-wire interface means it is easier to separate the PMIC from the point-of-load power stages, which can reduce the intensity of the hotspots around the processor.

The chip company is offering the AS3721 PMIC with a new AS3729 point-of-load regulator.

The feedback loop carried over the AS3721’s two-wire interface has fast response to keep the processor within its safe operating voltage even when supplying fast-changing loads.

Using an output capacitor of just 40µF and at an output voltage of 1.0V, the system’s voltage drop during a step up from 0.5A to 5A in burst mode is just 32mV (typical).

Higher current capability is becoming important as smartphones move to higher resolution displays with higher power budgets.

The AS3729 regulator contains NMOS and PMOS FETs for each of two phases, which can be controlled separately and can handle an output current of 2.5A.

See also: Globalfoundries claims 3D chip breakthrough with TSVs

Courtesy of:
Richard Wilson

AMS uses 3D chip technology for smartphone sensors