High-Voltage Integrated Class-B Amplifier for Ultrasound Transducers - PowerPoint PPT Presentation

High-Voltage Integrated Class-B Amplifier for Ultrasound Transducers Dario Bianchi 1 , Fabio Quaglia 1 , Andrea Mazzanti, Francesco Svelto Università degli Studi di Pavia (1) STMicroelectronics

Outline • Linear Drivers for ultra-sound imaging : Apodization & Harmonic detection • Implementation of a High-Voltage Amplifier for Ultrasound Imaging • Experiments • Conclusions

Ultrasound System Block Diagram Linear Pulser Amplifier Improve image quality High Efficiency, Simplicity (Apodization, Harmonic Imaging) 1

Apodization & Harmonic Imaging Linear Pulser Acoustic Amplifier Pressure Focalization Point Sidelobes Transmit at f 0 Receive echoes at 2f 0 Need TX with low emission at 2f 0 2

Linear Amplifier Low-V Class-AB g m High-V Class-B TIA for high linearity & gain- + for minimum power bandwidth product dissipation V/I & I/V Conversion Single Stage Solution BCD6-SOI Transducer B IPOLAR 5V NPN HF L min =0.35 μ m C MOS L min =1 μ m D MOS V ds_max =100V f T_n =6GHz f T_p =2.2GHz 3

High Voltage Class-B Transimpedance Stage R L =100 Ω C L =150pF • For minimum quiescent power consumption, devices are biased in sub-threshold 4

Large Signal Frequency Response g V ≈ m in V ω out C X g C x Signal Describing m = GBW dependent Function π 2 C X 5

High Impedance Node Capacitance Made of parasitcs of C p M 5 , M 8 , M 9 , M 11 C buf Signal dependent C + C gs_N gs _ P = C buf 1 + G R M L Tranconductance Describing Function: β 4 V I OD O = = G π M 3 V OD ω 0 6

High Impedance Node Capacitance Target g m GBW = > 500 MHz π 2 C X @2V pp C x =13.4pF [ 60 mS ] > 42 g m mS @2V pp GBW = 713 MHz C x =13.4pF @80V pp GBW = 1 . 2 GHz C x =8.1pF 7

Chip Micrograph Technology: Packages: BCD6-SOI CERDIP Active Chip area: <1 mm 2 Power consumption: 37 mW High Voltage Supply: Pulsed-wave ± 50V Measurements limit dissipation Low Voltage Supply: ± 3V Test chips realized by STMicroelectronics 9

Pulse Response & Voltage Gain SR+ =2KV/ μ s 80V SR-=2.2KV/ μ s f MAX ≈8MHz 40V 10V GBW@2V pp =665MHz BW@2V pp =5MHz GBW@80V pp =720MHz BW@80V pp =6.5MHz 8

Conclusions • A new integrated power amplifier able to deliver peak powers of 20W while consuming a static power of 37mW only has been presented • It is based on a low-voltage g m and a high-voltage TIA closed in a feed-back loop • Describing function approach has been proposed for the analysis of signal-dependent gain and frequency response 10