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.
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