Patent ID: 7986931

Claim:
An echo cancellation circuit for an RFID reader, comprising: a gain calculator for providing a complex gain value according to a carrier signal and a received signal, wherein the complex gain value is calculated according to the following formula: α =E[V m ×V f *]/E[V m ×V m *], wherein α is the complex gain value, V f is the received signal, V f * is a complex conjugate of the received signal, V m is the carrier signal, V m * is a complex conjugate of the carrier signal, E[ ] means the expectation operation of the signal inside the brackets; a gain adjustment circuit coupled to the gain calculator for multiplying the carrier signal by the complex gain value, and outputting the result of the multiplication; and a subtraction circuit coupled to the gain adjustment circuit for subtracting the output of the gain adjustment circuit from the received signal, and providing the result of the subtraction as an output signal of the echo cancellation circuit.