ece 17 final presentation portable ultrasound driver
DESCRIPTION
Senior Design Project at Drexel University Presentation of Miniaturized, Portable Ultrasound Driver for Clinically Relevant ApplicationsTRANSCRIPT
Team Number: ECE-17
Team Advisor: Dr. Peter A. Lewin
Miniaturized, Portable UltrasoundDriver for Clinical Applications
• Maryam Ahmad Electrical Engineering• Jeff Kinslow Computer Engineering• Dan Rivas Electrical Engineering• Jesse Spade Electrical Engineering
Problem Description
• Current solutions for chronic wound
management have high cost, poor mobility
• Provide a viable alternative to chronic wound management
• Implemented as a low
frequency (30-100 kHz),
miniaturized, portable ultrasound applicator
• Assemble final breadboard prototype – Component Testing– Systems Integration and Integration Test
• The circuit will produce a waveform of zero-crossing tone-bursts with these attributes:
– Tone Burst Sinusoidal Frequency Range:30 kHz – 100 kHz
– Tone Burst Duration: 20 ms – 200 ms
– Pulse Repetition Frequency: 1 Hz – 30 Hz
– Output Voltage: 50 -100 Vp-p
Goals
Timer Module
DC-to-DC Converter
Battery
PowerAmplifier
Oscillator
Block Diagram
Transformer
To Ultrasonic transducer
Oscillator
Waveform Generation: Tone Burst
• Sinusoid Waveform Synthesis
• Analog Devices DDS AD9831
– Functionally identical to AD9832
– Parallel programming interface instead of serial
• ~1.1 Vp-p Sine Wave
• 0 Hz – 17.5 MHz (Master Clock Freq./ 2 )
• On-Board this CMOS chip:
– Numerically Controlled Oscillator (NCO)
– Sine Look-up Table (LUT)
– 10 bit Digital-to-Analog Converter (DAC)
Timer Module
Waveform Generation: Tone Burst
Programmed with AD software tool
via Parallel DB25 to Centronix 36 pin
Timer Module
Oscillator
Waveform Generation – Duty Cycle
• Microchip PIC12F683 Microcontroller
• Generated Duty Cycle will gate the AD9831 to produce tone-bursts
• 1.95 Hz – 17.5 MHz
• Software Library
– Enumerated list of frequency/Duty
Cycle pairs
– Functions for high-level programming
Waveform Generation – Duty Cycle
• Sample program, using our C library, to produce a 33% Duty Cycle at 30 Hz using the PIC12F683
• Compiled with freely licensed and freely available MikroElektronika microC compiler v1.6.5 (2009)
void main(){ setIOdir(GP5, OUTPUT); setOscillatorFreq(FREQ_125_KHZ); // 125kHz CLK setPWM(F_30H_D_33); // 30 Hz, 33% Duty Cycle
for(;;) { // Do nothing, let PWM continue }}
Waveform Generation – XR2206
• Monolithic Function Generator
• Functional replacement for AD9831 for presentation purposes
• Not programmable, requires external circuitry to change functionality
Optimizing Power Transfer
• Impedance matching– achieve maximum power efficiency– suppress undesired signal reflection
• Voltage step-up and current step down transformer
• Frequency of Operation:30 kHz – 100 kHz- Turns Ratio: 1:6
Testing Transformer – T36-1-X65
• T36-1-X65 from Mini-Circuits
– Turns ratio 1:6
– Frequency of Operation: 30 kHz – 20 MHz
– Successfully amplified the output signal of the operational amplifier, for an input signal to the amplifier ranging from 100 mVp-p to 500 mVp-p
– Distortion for input signals greater than 500 mVp-p
T36-1-X65 – Reason for Distortion
• Insertion Loss
Frequency (MHz)
Insertion Loss (dB)
0.03 2.44
0.05 1.60
0.10 0.89
0.20 0.69
0.27 0.67
0.47 0.55
2.17 0.38
4.66 0.50
20.00 2.38
Chosen Transformer
Implemented Transformer
• Audio Transformer F28050 from Pico Electronics
– Turns ratio of 3.06:1 (primary : secondary) in series configuration
– Turns ratio of 6.12:1 (primary : secondary) in parallel configuration
– Frequency of operation : 400 Hz – 250 kHz
– Successfully amplified the output signal of the operational amplifier, for an input signal to the amplifier ranging from 100 mVp-p to 600 mVp-p
Test results for Audio Transformer (F28050)
• Distortion for an input signal greater than 600 mVp-p
• Distortion: Frequency dependent
Input Signal :1 Vp-p @ 30 kHz, 100 kHz
Output Signal : 29.4 Vp-p , 34.1 Vp-p
• Achieved by boosting the current of the operational amplifier (by using complimentary Darlington pair) to 1 A
Input Signal : 1.1 Vp-p @ 30 kHz, 100 kHz
Output Signal from the transformer : 37.7 Vp-p
Test Results for F28050 with Minimal Distortion
Power Amplifier
• OPA453 by Texas Instruments
– Power-Supply Range of ±10 V to ±40 V
– 50 mA Continuous Current
• Piezoelectric Transducer
– 2.17 nF @ 30 kHz
• Transformer
– 100 Ω @ 30 kHz
Power Amplifier – Test Configurations
•Input signal (Tone-Burst) 780 mVp-p at 30 kHz
•Load Transformer Impedance
–Turns Ratio (n = 6.12)100 Ω @ 30 kHz
•Variable Gain
–20 V/V or 26 dB for 100 VP-P
–17 V/V or 24 dB for 80 VP-P
–10 V/V or 20 dB for 50 VP-P
•Required Current
–163 mA for 100 VP-P
–131 mA for 80 VP-P
–81 mA for 50 VP-P
Power Amplifier Modification
• “Master”, “Slave” Configuration
– Boosted Current : Approximately 100 mA
• Limitations
– Before the master slave configuration, input signal maximum ~ 500 mVp-p
– After master slave configuration signal distortion with 700 mVp-p tone-burst input signal
• Conclusion
– More load current was necessary
Power Amplifier – Final Configuration
• External Darlington Output Transistors– Boost output current
up to 1 Amp
• Maximum Input Signal– Increased above
780 mVp-p – Sufficient for desired
output signal
– Maximum Vp-p : 97.6 V (Measured with 10 :1 probe)
Tested DC-to-DC Converter
• Texas Instruments DCH010515D
• Unregulated dual output converter
• Measured Output (Vin=3.7V)
– To amplifier:
• Vout = 24.5V
• Problem
– Op-amp needed higher voltage in order to provide sufficient current to the transformer
Implemented DC-to-DC Converter
• Pico Electronics 5A28D– Unregulated dual output converter– Vin = 3.7 V, Vout = ±20 V– Switching Frequency : 40 kHz
• Noise Issues– A ripple at the input to the operational amplifier
power supplies caused distortion in the output signal
Improved Output Signal
Solution : Shunted 10 uF, 10 nF, 100 pF capacitors to ground to filter out the unwanted ripple
Input Noise
• Input Noise
– Converter projected noise onto the input signal to the operational amplifier
• Solution
– Applied two 2.2 µF capacitors between + Vin and – Vin
Input Signal without Filter
Input Signal with Filter
Battery UBP005 – Implemented solution
• Supply Voltage
- 3.7 V
• Supply Current
- Minimum of 355 mA
• Size:
- 1.22 in x 2.22 in x 0.22 in
• Only a single battery needed
Power Budget - Battery
• Battery Life = (Ib / Id) * 0.7
– Ib = Total capacity rating of the battery, mAh
– Id = Current consumption of the device, mA
Capacity Rating of Battery (mAh)
Current Consumption by the DC-DC converter (mA)
Life of Battery (hrs)
Life of battery (# of 15 min sessions)
740 355 1.45 5
Final Prototype Schematic
Prototype Circuit
System Integration
•Channel 1 : (Unamplified waveform )
–Peak to Peak Voltage : 880 mVp-p ,
–Frequency : 31.25 kHz
• Channel 2: (Amplified waveform)
–Peak to Peak Voltage : 84.0 Volts
–Measured with 10:1 probe
Waveform of Piezoelectric Transducer as the load
•Channel 1: Output pulse of the transducer
– Peak to Peak Voltage : 33.6 mV
•Channel 2 : Output pulse of the driving circuitry
– Peak to Peak Voltage : 78 mVp-p ,
– Measured with 10:1 probe
Video Demonstration
Prototype Budget
Labor Costs(@ 30% Fringe Benefits)
$125,280
Lab Costs $41,990
Electrical Components $423.50(prev. $333.62)
Overhead(@125%)$210,964
(prev. $209,505)
Grand Total Engineering Development Cost
$379,735(prev. $377,109)
Industrial Budget Summary
Gantt Chart
– Tone Burst Sinusoidal Frequency Range:30 kHz – 100 kHz
– Tone Burst Duration:20 ms – 200 ms
– Pulse Repetition Frequency:1 Hz – 30 Hz
– Output Voltage (to drive Transducer):50 -100 Vp-p
– Programmable– Miniaturization (3 cm x 3 cm)
Summary – Goals
Team Number: ECE-17
Team Advisor: Dr Peter A. Lewin
Miniaturized, Portable UltrasoundApplicator for Clinical Applications
• Jeff Kinslow Computer Engineering• Maryam Ahmad Electrical Engineering • Jesse Spade Electrical Engineering • Dan Rivas Electrical Engineering
Thank You.Special Thanks to Dr. Lewin and Youhan Sunny