New digital quadrature demodulator for real-time hand-held ultrasound medical imaging device

A real-time, low-power digital quadrature demodulator is proposed to process ultrasound radio frequency signals in both pulse and continuous modes. Two finite impulse response filters are combined to build a Hilbert transform and a linear approximation architecture that allows achieving the required square root operations of quadrature demodulator. The complexity and accuracy of proposed demodulator are analyzed and successfully integrated in an FPGA as a low-power building block. Results show the proposed digital back-end demodulator is accurate, which motivates us to integrate in a miniaturized ultrasound receiver. Only 12 MULT18times18 and 1473 slices of the FPGA resources were required to synthesize the quadrature demodulator. Also, real-time images were acquired from a reference phantom demonstrating the feasibility of using the proposed architecture to accomplish real-time digital quadrature demodulation of echoes resulting from ultrasonic signals.