Abstract: The present Specification is directed to the heterogeneous integration of compound-semiconductor devices on indirect-bandgap material substrates. A chip comprising compound-semiconductor layer stack disposed on a handle substrate of germanium is bonded, stack-side down, to a silicon layer disposed on a host substrate. The use of a germanium handle substrate enables the handle substrate to be removed after bonding using methods that are highly selective for germanium over the compound semiconductor layer stack. As a result, the compound-semiconductor layer stack does not need to be protected during handle substrate removal and the handle substrate can be completely removed without causing damage to the compound-semiconductor layer stack. As a result, after handle-substrate removal, the materials of the layer stack can be processed further to define one or more optically active devices in conventional fashion.

Abstract: Ultrasound information for B-mode and CW Doppler mode use the same digital beamformer. Due to sigma-delta conversion or over sampling, sufficient dynamic range is provided for the desired bandwidth. By mixing the input ultrasound information to base band before conversion, additional dynamic range may be provided. The electrical impedance may be better matched to elements by connecting a different number of sigma-delta converters to an element. Elements with lower impedance may be connected to a plurality of sigma-delta converters. To increase the aperture size for elements with a higher impedance, the same sigma-delta converters may be used as separate receive beamformer channels without the summation.

Abstract: Ultrasound information for B-mode and CW Doppler mode use the same digital beamformer. Due to sigma-delta conversion or over sampling, sufficient dynamic range is provided for the desired bandwidth. By mixing the input ultrasound information to base band before conversion, additional dynamic range may be provided. The electrical impedance may be better matched to elements by connecting a different number of sigma-delta converters to an element. Elements with lower impedance may be connected to a plurality of sigma-delta converters. To increase the aperture size for elements with a higher impedance, the same sigma-delta converters may be used as separate receive beamformer channels without the summation.

Abstract: Receive beamformers for receive beamforming ultrasound information include a plurality of channels. The received signals for each channel are oversampled for conversion to digital form, such as sampling with a sigma-delta converter. The reconstruction of the samples into data at the Nyquist or other rate is performed in stages. Partial reconstruction to a rate less than the oversampling rate, but greater than the Nyquist rate, occurs prior to summation across channels. Delays are implemented by selecting data from the sample stream. After summation, the samples are reconstructed at a Nyquist or other rate.