Patent ID: 8115597

Claim:
A power rectifier for a Radio Frequency Identification tag circuit, comprising: a first antenna input node for receiving a first phase of an alternating RF wireless signal; a second antenna input node for receiving a second phase of the alternating RF wireless signal which is substantially opposite to the first phase; a plurality of serially coupled stages, at least one of the stages including a first synchronous element with a first beginning coupled to receive the second phase and a first ending, the first synchronous element including: a first transistor having an input terminal at the first beginning, an output terminal, and a gate coupled to receive the first phase; and a second transistor having an input terminal, an output terminal at the first ending, and a gate coupled to receive the second phase, in which the input terminal of the second transistor is connected to the output terminal of the first transistor at a first intermediate node so as to form a first charge-accumulating path between the first beginning and the first ending, and there is no charge-accumulating path between the first beginning and the first ending other than the first path; and a second synchronous element with a second beginning to receive a first phase and a second ending, the second synchronous element including: a third transistor having an input terminal at the second beginning, an output terminal, and a gate coupled to receive the second phase; a fourth transistor having an input terminal, an output terminal at the second ending, and a gate coupled to receive the first phase, in which the input terminal of the fourth transistor is connected to the output terminal of the third transistor at a second intermediate node so as to form a second charge-accumulating path between the second beginning and the second ending, and there is no charge-accumulating path between the second beginning and the second ending other than the second path; and in which the second beginning is coupled to the first ending.