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

High-Voltage Integrated Class-B Amplifier for Ultrasound Transducers

Dario Bianchi1, Fabio Quaglia1, 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

High Efficiency, Simplicity Improve image quality (Apodization, Harmonic Imaging) Pulser Linear Amplifier

1

Apodization & Harmonic Imaging

Transmit at f0 Receive echoes at 2f0 Need TX with low emission at 2f0

Acoustic Pressure Focalization Point

Pulser Linear Amplifier

Sidelobes

2

Linear Amplifier

Low-V Class-AB gm

for high linearity & gain- bandwidth product High-V Class-B TIA for minimum power dissipation + V/I & I/V Conversion Single Stage Solution

BCD6-SOI

BIPOLAR 5V NPN HF CMOS Lmin=0.35μm DMOS Lmin=1μm Vds_max=100V fT_n=6GHz fT_p=2.2GHz

3

Transducer

High Voltage Class-B Transimpedance Stage

• For minimum quiescent power consumption, devices are biased in

sub-threshold RL=100Ω CL=150pF

4

Large Signal Frequency Response

5

X in m

C ω V g V ≈

• ut

X m

C π g GBW 2 =

Cx Signal dependent Describing Function

High Impedance Node Capacitance

6

Signal dependent

L M P gs

R G C C C + 1 + =

_ gs_N buf

Cp Made of parasitcs of M5, M8, M9, M11 Cbuf

π V β V I G

OD ω OD O M

3 4 = =

Tranconductance Describing Function:

High Impedance Node Capacitance

@2Vpp Cx=13.4pF @80Vpp Cx=8.1pF

MHz GBW 713 = GHz GBW 2 . 1 = MHz C π g GBW

X m

500 > 2 =

7

Target

mS gm 42 > ] 60 [ mS

@2Vpp Cx=13.4pF

Chip Micrograph

Test chips realized by STMicroelectronics

Technology: BCD6-SOI Active Chip area: <1 mm2 Power consumption: 37 mW High Voltage Supply: ±50V Low Voltage Supply: ±3V Packages: CERDIP Pulsed-wave Measurements limit dissipation

9

Pulse Response & Voltage Gain

10V 40V 80V SR+ =2KV/μs SR-=2.2KV/μs fMAX≈8MHz GBW@80Vpp =720MHz GBW@2Vpp =665MHz

8

BW@2Vpp=5MHz BW@80Vpp=6.5MHz

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 gm 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