The principles of oversampling are exploited in a simple beamforming architecture using a single bit delta-sigma (DeltaC) analog to digital converter (A/D) on every channel. The high sampling rate required for the single bit A/D provides adequate delay accuracy for high quality beamforming using elementary sample manipulations. Images produced with this beamformer exhibit significant artifacts directly related to dynamic focusing. However, a simple digital recording technique following delays permits dynamically focused beamforming without degrading image quality. The simplicity of this beamformer compared to conventional methods may facilitate very large channel count or low power beamformers suitable for 1.5-D arrays or portable scanners.

Oversampled analog to digital converters (delta-sigma NDs) have been proposed to radically reduce the size, cost and power consumption of digital ultrasound beamformers. Simply replacing conventional A/Ds with single bit oversampled versions, however, produces significant image artifacts for a dynamic focus system. In addition, spectral Doppler measurements are severely compromised. Here, we disclose a complete beamformer exploiting oversampling principles on both transmit and receive that doesn't suffer from these problems. The architecture preserves the simplicity of an oversampled design, yet produces as sensitive spectral Doppler measurements. In this high quality B-Scan and color flow images, as well talk we present simulations and emulations using actual array data, to demonstrate the capabilities of the system.

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Delta-sigma (DeltaSigma) modulators can implement a simpler digital ultrasound beamformer than can traditional architectures based on multi-bit analog-to-digital converters (A/D). The signal-to-noise ratio (SNR) of the DeltaSigma modulators, however, suffers from limited oversampling ratios. To improve the SNR of each channel, a mixing signal heterodynes narrowband signals to lower frequencies where the baseband DeltaSigma modulator performs better. Noise figure analyses are presented that illustrate the effectiveness of this technique in improving noise performance. Also, spectral Doppler and color flow simulations are presented that realistically emulate a 32 channel oversampled beamformer and compare these results with traditional and ideal systems.

High-performance and efficient beamforming circuitry is very important in large channel count clinical ultrasound systems. Current state-of-the-art digital systems using multi-bit analog to digital converters (AIDs) have matured to provide exquisite image quality with moderate levels of integration. A simplified oversampling beamforming architecture has been proposed that may allow integration of delta-sigma () AIDs onto the same chip as digital delay and processing circuitry to form a monolithic ultrasound beamformer. Such a beamformer may enable low-power handheld scanners or high-end systems with very large channel count arrays. This paper presents an oversampling beamformer architecture that generates high-quality images using very simple digitization, delay, and summing circuits. Additional performance may be obtained with this oversampled system for narrow bandwidth excitations by mixing the RF signal down in frequency to a range where the electronic signal to noise ratio of the A/D is optimized. An oversampled transmit beamformer uses the same delay circuits as receive and eliminates the need for separate transmit function generators.