#338 – An Interview with Jørgen Jakobsen

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As mentioned in the intro blurb, Chris has revised his Australia / NZ plans and will be doing meetups. Check out the current plans and get in touch if you’d like to meet up!

Welcome Jørgen Jakobsen!

• There is a large hearing aid industry in Copenhagen, based around acoustic companies in the area, as well as  the Denmark Technical University (DTU), where there is a focus on IC design.
• Jørgen’s early job was at Ericsson.
• Nokia was also a presence in Copenhagen, making the 3310 (which is making a comeback)
• He left those to join a startup called Silicide with a former co-worker. Bluetooth spec was out, but the company only worked on the first 15 pages in their silicon (with external control).
• The Die photo of the esp32 shows that 10% of the IC is the analog components.
• The higher voltage process is often a BCD process. They are currently on 180nm, which suits their needs fine (especially because it’s a well understood process node).
• After the startup, he joined Oticon A/S. They had 10 analog IC designers!
• A typical hearing aid is composed of
  • 2 microphones
  • Beam forming/noise cancellation
  • ADC
  • Filtering
  • Compression
  • Speaker
  • Battery charging
  • Sub 1mA
• Thought they’re starting to adopt bluetooth, many of the hearing aids need to still support Telecoil
• The chip stack for a hearing aid is usually:
  • DSP
  • Analog
  • Memory
• It is overall an insular industry, because of the specific skills required and because of the patent pool that exists.
• Testing chips needs to happen in less than 4 seconds, including all the analog tests.
• Jørgen’s latest enterprise is designing IC amplifiers at Merus Audio. These are all Class D amplifiers.
• Maintaining at the halfway point between the 12V and GND, there are switching losses. They even patented how to turn on transistors in a new way!
  • https://www.google.com/patents/WO2012055968A1?cl=zh
  • https://www.google.com/patents/WO2013164229A1?cl=zh
• They do 5 level modulation now (paper about it on IEEE), instead of 3. Check out the datasheet for the ML12070, which does this.
• There are “listening” and “party” levels for sound.
• The rise of amazon echo and similar voice connected devices will eventually want to switch to battery power.
• When the DACs/Amps are driving either side of the speaker, it’s called a bridge tied load.
• The communication method with the chip is i2s.
• Jørgen has been playing around with the new esp32, which has 2 channels of i2s. He has built a full 128kb mp3 audio streaming decoder running on the ESP32 with an i2s hookup to the input amplifier
• He has pulled in other low cost development tools, setting up automated testing using Raspberry Pi’s
• The power output on these chips maxes out at 2×70, which is based around the crest factor.
• Apparently K Pop is the most dynamic/loud music for testing audio chips.
• Jørgen recommends hanging out on hackaday.io for finding people to discuss new ideas and code.
• Check out more about the new chips coming from Merus Audio on their website.