A Single Channel Multiplier Circuit For Ultrasonic Doppler Echo Signal Demodulation

Ultrasound Doppler technology has been widely used in clinical practice,such as ultrasound Doppler fetal heart rate measurement,ultrasound Doppler blood flow velocity measurement,ultrasound medical imaging,etc.In the traditional ultrasound Doppler system,echo signals are demodulated using the quadrature demodulation.The quadrature demodulation circuit is complicated and requires high peripheral circuits and the amount of data for data processing is large.Aiming at the problems of quadrature demodulation and extracting more accurate ultrasonic Doppler frequency shift signals,this paper designs a single-channel multiplier demodulation circuit.The main research work is as follows:1.A single-channel multiplier circuit for ultrasound Doppler echo signal demodulation is proposed.One input of the circuit is ultrasound Doppler echo signal,and the other is a sinusoidal signal with a fixed difference in frequency from the transmitted signal.After filtering the output signal of the multiplier circuit by a low-pass filter,the required ultrasound Doppler frequency shift signal can be obtained.The theoretical analysis,software simulation and circuit test prove that the circuit can demodulate the signal accurately.2.On the basis of the designed single-channel multiplier demodulation circuit,a continuous ultrasound Doppler system is built by combining the transmitting module,AD conversion module,etc.At the same time,a traditional AD8333 quadrature demodulation circuit is built for comparison.The experimental results show that under the same experimental conditions,the designed single-channel multiplier circuit can achieve a demodulation effect equivalent to the quadrature demodulation,which proves that the designed single-channel multiplier circuit can demodulate ultrasound Doppler echo signals.3.In order to simulate the movement of human organs to generate Doppler echo signals with different parameters,a Doppler signal simulator is designed.The experiment verifies the demodulation ability of the single channel multiplier circuit proposed in this paper,and becomes a new choice for the signal demodulation module in the ultrasonic Doppler system...