Patent ID: 6711397
Filing Date: 2004-03-23
Classification: H03D,H04B

Abstract:
A direct conversion receiver for converting a radio frequency modulated signal into a corresponding baseband signal without requiring conversion through an intermediate frequency while abating local oscillator leakage, increasing dynamic range and increasing RF selectivity, the direct conversion circuit comprising the following:an oscillator component configured to generate a plurality of binary control signals, each binary control signal having a frequency substantially equal to the radio carrier frequency of the radio frequency modulated signal or substantially equal to the odd subharmonic of the radio frequency modulated signal, the plurality of binary control signals including the following: a first binary control signal that has a duty cycle of approximately twenty-five percent of the radio frequency modulated signal where the first binary control signal is high; a first complement binary control signal that is the approximate complement of the first binary control signal; a second binary control signal that is approximately 180 degrees out of phase with the first binary control signal and that has a duty cycle of approximately twenty-five percent of the radio frequency modulated signal where the second binary control signal is high; and a second complement binary control signal that is the approximate complement of the second binary control signal; a plurality of switches, each switch having an input, an output, and control terminals, each switch configured to pass the radio frequency modulated signal from its input terminal to its output terminal according to the control signals on its control terminals, the plurality of switches comprising the following: a first switch configured to receive at its control terminals the first binary control signal and the first complement binary control signal; and a second switch configured to receive at its control terminals the second binary control signal and the second complement binary control signal.