Patent ID: 8385874

Claim:
A discrete time direct sampling circuit, comprising: a first differential voltage-to-current convertor that converts an analog radio frequency signal input to differential analog radio frequency current signals, at a first predetermined voltage-to-current conversion rate; a positive-phase sampling mixer that samples a positive-phase analog radio frequency current signal outputted from the first differential voltage-to-current convertor by a first sampling signal that is based on a local signal, and outputs the sampled signal at a timing in accordance with a first read control signal that is based on the local signal; a negative-phase delay sampling mixer that samples a negative-phase analog radio frequency current signal outputted from the first differential voltage-to-current convertor, by a second sampling signal that is based on the local signal, and outputs the sampled signal at a timing in accordance with a second read control signal that is delayed to the timing in accordance with the first read control signal by a predetermined sample timing; and a combining output section that combines a sampling value read out from the positive-phase sampling mixer and a sampling value read out from the negative-phase delay sampling mixer and outputs the combined value, wherein: the positive phase sampling mixer comprises: a first mixer switch that allows the positive-phase analog radio frequency current signal to pass, based on the local signal; a plurality of first sampling taps that output electric charges charged by a current signal passing the first mixer switch based on first sampling control signals, according to the first read control signals that are based on the local signal; and a first reset switch that resets the electric charges charged in the plurality of first sampling taps, according to a reset control signal that is based on the local signal; the negative-phase delay sampling mixer comprises: a second mixer switch that allows the negative-phase analog radio frequency current signal to pass, based on the local signal; a plurality of second sampling taps that that output electric charges charged by a current signal passing the second mixer switch based on second sampling control signals, according to the second read control signals that are based on the local signal; and a second reset switch that resets the electric charges charged in the plurality of second sampling taps, according to the reset control signal; the first sampling control signals in the plurality of first sampling taps comprises control signals of varying sample timings; the first read control signals in the plurality of first sampling taps comprise signals of varying sample timings; the plurality of second sampling control signals in the plurality of first sampling taps comprise control signals of varying sample timings; and the second read control signals in the plurality of second sampling taps comprise signals of varying sample timings.