An Interview with Kendall Castor-Perry

Welcome Kendall Castor-Perry, the Filter Wizard!

• Working on filters after high school and saw a "Wireman wanted" sign at Kemo.
• Stayed for 21 years, but got started sweeping the floors.
• Heath Robinson vs Rube Goldberg
• Learned out of databooks
• Where do you point people for filters?
  • Not the Active Filter cookbook, though many would recommend it.
  • Circuit theory courses online
  • Starting with a scope
• Parents owned a big house, rented out rooms, tenants would need help with record players
• Moog's ladder filter, which is a voltage controlled filter
• Kemo was general purpose lab instruments.
• Filters requirements were moving faster than the engineer knowledge.
• The days where you had to have filtering in front of a sampling ADC
• Moved to Burr Brown to work on DACs
• PCM1704
• Filtering at the front end is only if you want really want super low noise or if there is a wide bandwidth front end
• Broadly speaking the filtering has gone inside chips
• "My job has always been to chase signals around"
• A transducer is a piece of instantiated physics that turns a signal into a datastream
• "Think of me as the Van Helsing of electronic design"
• Information theory
• SERDES
• Using power supply instead of a voltage reference on DACs.
• Then Kendall went to work at Cypress Semiconductor (makers of the PSOC among other things)
• Doug Self
• Making your own resistor could be a source of distortion
• SPICE isn't bound by physics
• Paul Rako
• When you add components you lose the systems thinking for your design
• Bob Pease skeptical of simulation (Paul wrote about what he really felt later)
• SAPWIN - symbolic analyzer
• FIR filter
• "Pessimal signal" (opposite of "optimal" because it's pessimistic)
• KHN - state variable filter
• Prototyping using SPICE
• Karl Popper
• Disproof is the only thing the matters
• Eric Bogatin's rules for engineers
• Different types of filters
• Monte Carlo analysis
• Cypress active in the USB Audio space...the microphone we sent to Kendall may have had a chip in it he helped design!
• Synchronous mode of USB audio
• Follow the #FilterWizard on LinkedIn (or follow his profile page) or check out his published articles on Planet Analog