| 主权项 |
1. An energy harvesting system comprising:
(a) an energy harvester having an output impedance; (b) a first DC-DC converter for converting an input voltage received from an output conductor of the energy harvester to an output signal, the first DC-DC converter having an effective input impedance equal to Vin÷Iin controlled by the input voltage to match the output impedance of the energy harvester so as to provide maximum power point tracking (MPPT) between the energy harvester and the first DC-DC converter, wherein the MPPT circuit includes a replica impedance coupled between the output conductor of the energy harvester and a reference voltage, the replica impedance having a value which is a predetermined multiple of the harvester output impedance determined by: Zr=N×Zi=Vin÷Iin, where Zr is the replica impedance, N is the predetermined multiple which is a positive number greater than 1, Zi is the output impedance of the energy harvester, Vin is the output voltage of the energy harvester and Iin is the output current of the energy harvester, Vin÷Iin is the effective input impedance of the DC-DC converter, wherein a feedback current of Iin÷N flows through the replica impedance, and the MPPT circuit includes a transistor coupled between a conductor and the replica impedance, the feedback current flows through the conductor, and wherein the MPPT circuit also includes an amplifier having a first input coupled to the output conductor of the energy harvester, an output coupled to a control electrode of the transistor, and a second input coupled to a junction between the transistor and the replica impedance; and (c) an output couplable to a receiving device to receive the output signal. |
