Office of Technology Transfer – University of Michigan

Analog-Digital Hybrid Controller Architecture for Load-Adaptive Power Transistor Scaling in PWM Switching Power Converter

Technology #6734

Questions about this technology? Ask a Technology Manager

Download Printable PDF

Euisik Yoon
Managed By
Joohee Kim
Licensing Specialist, Physical Sciences & Engineering 734-764-8202
Patent Protection
US Patent Pending
PWM buck converter with >80% PCE in 45μA-to-4mA loads using analog-digital hybrid control for impiantale biomedical systems
Solid- State Circuits Conference - (ISSCC), 2015 IEEE International, 2015

A discontinuous conduction mode (DCM) pulse width modulation (PCM) buck converter suited to systems that operate in energy-limited environments has been developed at the University of Michigan. Systems that operate in energy-limited environments (e.g., implantable biomedical systems) exhibit large variations in power consumption. Energy-efficient switching power converters that can support a wide range of load variation are required for such systems. Pulse frequency modulation (PFM) power converters can support large load variations with high power conversion efficiencies (PCE), but their unpredictable switching noise can degrade power supply integrity, and thereby, cause deterioration of the signal quality in the aforementioned systems. Pulse width modulation (PWM) power converters can provide predictable output spectra, but their PCE under light loads can be low. Additionally, despite advances in PWM converter technology, low PCE remains a challenge.

Design Details

The discontinuous conduction mode (DCM) pulse width modulation (PCM) buck converter developed at the University of Michigan overcomes the aforementioned challenges. By utilizing adaptive power gating and analog-digital hybrid (coarse/fine) control, the converter achieves a PCE of over 80% for wide load requirements (4μA to 4mA). Adaptive power gating reduces switching power overheads, whereas the digital control provides robust operation, and the analog control provides high accuracy. Overall, the design demonstrates enhanced light load efficiency by load-adaptive power transistor scaling, and load independent transient responses. Further, the design shows nonlinear behavior suppression and reverse inductor current suppression without a current sensor.


  • Power converters for energy limited systems


  • Enhanced light load efficiency by the load-adaptive power transistor scaling
  • Load independent transient response
  • Nonlinear behavior suppression
  • Reverse inductor current suppression without current sensor