US Patent 9246719 High dynamic range radio architecture with enhanced image rejection

A circuit for down-converting an RF signal to a baseband signal includes a trans-admittance amplifier adapted to receive the RF signal and generate in response a pair of differential current signals. The circuit further includes a trans-impedance amplifier having at least four mixers and at least four linear amplifiers. The four mixers frequency down-convert the pair of differential current signals to generate four pairs of differential baseband current signals, wherein each pair of the differential baseband current signals has a different phase and is associated with each of the linear amplifiers. Additionally, the circuit includes a summing block that generates an in-phase signal using a first weighted sum of the four different baseband current signals and a quadrature signal using a second weighted sum of the four different baseband current signals. The circuit further includes an analog-to-digital converter for converting the in-phase and quadrature signals to respective digital representations.