Caption: iC-PNE in 5x5 mm optoQFN32 (image: iC-Haus)

Next Generation Optical Phased Arrays for Improved Servo Feedback

Innovations in the field of high-resolution optical encoders - iC-Haus presents the next generation of the iC-PNE sensor series at the SPS 2023 - smart production solutions (Hall 4A, Booth 146).

Industrial drive controls require very fast and precise feedback of the servo motor rotor angle for the best possible load balancing. This is the area where high-resolution optical encoders come into play, scanning multiple Vernier tracks to achieve excellent resolution. The latest iC-PNE sensor series is blueready and can benefit from LED illumination in the near-UV range. It outputs particularly low distortion sinusoidal signals at 2,048 cycles per revolution for virtually latency-free direct feedback to the drive controller. At the same time, the high-contrast signals improve the accuracy of the iC-MNF interpolation circuit, which also performs the Vernier calculation. iC-PNE simplifies this task by adding sector detectors that read a complementary Gray code. This reduces the Vernier scale to angular segments that can be evaluated with a much higher error tolerance for the benefit of operational reliability.

Since the sector detectors operate autonomously from 1.8 V with low power consumption,
a battery-supported revolution counter can optionally be implemented via the MCU.

High resolution with minimal installation space
The optical sensors of the iC-PNE series require a small sensor area of only 1.9 mm x 3.3 mm to scan encoder code discs and generate sine signals in best "HiFi quality". The
evaluation is performed by interpolation ICs with Vernier calculation, especially the fast S&H converter iC-MNF, which allows extreme angular resolutions of up to 25 bits. Compared to conventional absolute encoder sensors, iC-PNE sensors read three incremental Vernier tracks as well as a 4-bit Gray code, which saves installation space and simplifies illumination. The small sensing area and high sensitivity of the sensors reduce the energy required for illumination, which benefits the life of the LEDs. The
phased arrays can be used with a blue LED, e.g. iC-TL46, which minimizes distortion and increases signal contrast; for devices reading only 512 periods per revolution, the encoders also fit standard IR LEDs (e.g. iC-TL85).

The photocurrent signals are converted into low-impedance and low-noise output voltages by a new low-noise amplifier design. Due to the high transimpedance amplification of typically 1 MOhm, an illumination of 2 mW/cm2 is sufficient to provide output signals of several hundred millivolts for the subsequent interpolation module. The iC-PNE devices are available for code disks of 26 mm, 33 mm or 39 mm and operate from 4.1 V over -40 °C to 125 °C. The optoQFN package used is very flat and saves valuable board space with an edge length of only 5 x 5 mm.

Nonius evaluation
Similar to the sliding caliper, whose scale principle was introduced by the French mathematician Pierre Vernier in the 17th century, iC-PNE increases the reading accuracy by means of multiple scales. The absolute position information is contained in the relative phase position of the signals. This requires a special type of evaluation, which the encoder interpolator iC-MNF provides with an interpolation depth of 14 bits.
iC-MNF has a separately adjustable signal conditioning with sample & hold stage for each channel, which holds the conditioned analog signal for subsequent sequential digitization.

A high-precision SAR
A/D converter with a resolution of up to 14 bits per sine period is available for this purpose. The nonlinear A/D converter uses the arctangent function and evaluates sine and cosine simultaneously. For angular position calculation, 2- and 3-track nonius scales are configurable, providing resolutions up to 25 bits (0.04 arc seconds out of 360 degrees).
The converter, which measures only 7x7 mm in the QFN48 package, is protected against reverse polarity and incorrect connection on the cable side and contains the RS422 transceiver for the serial data interface. The output is in SSI or BiSS protocol with clock rates up to 10 MHz. All major chip functions are monitored and can be configured for alarm messages. Typical sensor failures such as signal loss due to wire break, short circuit, contamination or aging are detected and reported to the controller.

A battery-powered multiturn counter as a software solution in the MCU can optionally complete the system. Due to the small form factor and low additional cost, this is a very interesting alternative for modular encoders, e.g. in robotic applications.

Experience a live demo of this new encoder solution at SPS - Smart Production Solutions
Nuremberg, November 14-16, 2023 Booth: 4A-146

Learn more about the innovations in the field of high-resolution optical encoders in our latest webinar: „Next Generation Optical Phased Arrays for Improved Servo Feedback“

Related products:

iC-PNE Series


Introducing iC-Haus
iC-Haus GmbH is a leading independent German manufacturer of standard iCs (ASSP) and customized ASiC semiconductor solutions. The company has been active in design, production, and sales of application-specific iCs for industrial, automotive, and medical technology for 39 years now and is represented worldwide.
The iC-Haus cell libraries in CMOS, bipolar, and BCD technologies are fully equipped to realize the design of sensor, laser/opto, and actuator ASiCs, among others. The iCs are assembled in standard plastic packages or using iC-Haus chip-on-board technology to manufacture complete microsystems, multichip modules, and sensors housed in optoBGA or optoQFN packages.

For any queries, please contact:
Joachim Quasdorf

iC-Haus GmbH, Am Kuemmerling 18, 55294 Bodenheim, Deutschland
Tel.: +49 6135 / 9292 306

Silvan Ettle
iC-Haus GmbH, Am Kuemmerling 18, 55294 Bodenheim, Deutschland
Tel.: +49 6135 / 9292 327

For more information, please contact:

iC-Haus GmbH
Am Kuemmerling 18, 55294 Bodenheim, Germany
Tel. +49 6135/9292-300
Fax +49 6135/9292-192

October 2023

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