The STHVUP64 is monolithic, high-voltage and high-speed pulse generator features 64 independent channels integrating a 64-channel beamformer for pulse generation in multi-channel medical ultrasound applications targeted at low power ultra-portable system.
A pure analog section provides each channel two half-bridges (two high-voltage P-channel and two high-voltage N-channel MOSFETs), a clamping-to-ground circuit and a transmitting/receiving switch structure which guarantees an effective isolation during the transmission phase. Each channel features also integrated high-voltage level translators, noise blocking diodes and an anti-leakage circuit.
Through a dedicated bit, channels can be programmed as a 3-level output or as a 5-level output. In 3-level mode, the two half-bridges are driven in parallel to provide a default peak current of 400 mA. However, it is also possible to program a low-consumption mode to decrease the overall power consumption: in this case, only one half-bridge is used and the output current lowers down to 200 mA. In 5-level mode, the two half-bridges can be driven independently, and each half-bridge has a current capability of 200 mA. The clamp circuit, used to force the XDCR<63:0> output pins down to GND, has a resistance of 45 Ω and a peak current capability of 0.32 A. The 64 independent T/R switches can be used in a multiplexing configuration.
The STHVUP64 also includes some global blocks: thermal protection circuits, undervoltage checks on VDDP3V3, VDDM3V3 and DVDD, a power-on-reset (POR) on DVDD and a global self-biased high-voltage MOSFET gate driver with internal check of the correct value and of the HV supplies.
All functions are managed by a digital core working at a maximum clock frequency of 200 MHz. This block manages the delay profiles used in the beamformer, the waveform generation and the various global settings and grants that all the device operations are performed in the correct sequence.