Comparison of DC-DC-converter architectures of power management circuits for thermoelectric generators

Future wireless sensor nodes will, for certain applications, require only a few microwatts of energy. Micro-machined thermoelectric generators can produce such amount of electrical energy, but variations in the generated power and voltage make a power management circuit necessary to generate a suitable power supply for the sensor node. This paper compares 2 options for such a circuit. We present one power management circuit for a thermoelectric generator that contains a DC-DC-converter with an inductor and one with capacitors. The converter with inductor has the advantage that the conversion factor can be set very precise. But for an efficient implementation, a large inductor is required. This inductor prevents the solution from being small and efficient at the same time. The use of an integrated charge pump however, will allow a more efficient circuit than a DC-DC-converter with an integrated inductor, even though the conversion factor is less flexible. Ultimately, the type of application will impose the type of DC-DC-converter that will be used.