Application Cases

【Overview】

In this study, the Aigtek ATA-2022B high-voltage amplifier was used to build an ultrasonic motor experimental platform. The effectiveness of the multilayer stacked structure in reducing driving voltage and improving driving force was verified, ultimately leading to the development of a high-precision, compact driving solution suitable for intelligent terminals.

Experiment name: Fabrication and performance testing of multilayer miniature linear ultrasonic motors

Research directions: Research on longitudinal-bending composite mode driving mechanism, microstructure design of multilayer piezoelectric stacks, modal composite algorithms and dynamic simulation, optimization of low-temperature co-fired ceramic (LTCC) processes, electrical parameter testing of piezoelectric vibrators, and motor driving performance optimization testing

Experimental objective: Aiming at the synergistic requirements of mobile terminal camera modules for actuators with micro size, low voltage, long stroke, and large thrust, and breaking through the performance limitations of traditional linear electromagnetic motors, this study designs a multilayer miniature linear ultrasonic motor based on a longitudinal-bending composite mode, completes its microstructure design, modal composite simulation, low-temperature co-fired ceramic process fabrication, and polarization treatment, tests its electrical parameters and driving performance, verifies the effectiveness of the multilayer stacked structure in reducing driving voltage and improving driving force, and ultimately develops a high-precision, compact driving solution suitable for intelligent terminals.

Test equipment: Signal generator (SDG1022X, SIGLENT), high-voltage amplifier (ATA-2022H, Aigtek), oscilloscope (SDS1072X, SIGLENT), ultrasonic motor, magnetic scale displacement sensor, tension/compression force sensor.

Experimental process: First, a piezoelectric vibrator with a single-layer film thickness of 30 μm and a total of 30 layers was fabricated using the low-temperature co-fired ceramic (LTCC) process. Polarization treatment of the vibrator was completed, and a system was built to monitor leakage current, ensuring that the leakage current at room temperature was below 20 nA. Then, a high-precision alumina driving foot was attached to obtain an ultrasonic motor with an overall size of 3.7 × 1.3 × 1.39 mm; subsequently, an impedance analyzer and a piezoelectric coefficient tester were used to test the impedance curve and piezoelectric strain constant of the vibrator, respectively, obtaining key electrical parameters such as resonant frequency and longitudinal piezoelectric strain constant; next, a motor performance testing system composed of a performance testing device, a microcontroller unit, and a voltage input device was built. Under different test conditions set in this system, frequency–speed, preload–speed, voltage–speed, and load–speed tests were carried out in sequence to determine the optimal driving frequency and optimal preload range of the motor, and to measure its core driving performance indicators such as maximum no-load speed and maximum load capacity under a driving frequency of 445 kHz and a preload of 450 mN, completing a comprehensive experimental verification of this multilayer linear ultrasonic motor.

Figure 1 Test system framework (a) Test block diagram; (b) Structural diagram of the performance testing device

Figure 2 Experimental platform

Experimental results:

1. In the piezoelectric vibrator fabrication and polarization experiment, a piezoelectric vibrator with 30 layers and a single-layer film thickness of 30 μm was fabricated using the LTCC process. The leakage current at room temperature was below 20 nA, indicating good polarization quality.

2. Electrical parameter testing of the piezoelectric vibrator showed that the resonant frequencies of the two branch channels were 447.50 kHz and 444.36 kHz, and the longitudinal piezoelectric strain constant was about 5662.2 pC/N, demonstrating reasonable resonance and piezoelectric performance.

3. Frequency–speed testing determined that the optimal driving frequency of the motor was 445 kHz, with a drivable frequency bandwidth of up to 65 kHz. At this frequency, the no-load speeds in the left and right directions were basically consistent, indicating good driving stability.

4. Preload–speed testing showed that the motor operated stably in the preload range of 300 mN–800 mN, had low sensitivity to preload, and still had considerable load-carrying capacity at low voltage.

5. Voltage–speed testing found that the minimum driving voltage of the motor was 3.2 Vpp, and the maximum no-load speed of 104.5 mm/s was reached at 6.2 Vpp. Excessive voltage would cause a slight decrease in driving speed due to temperature rise.

6. Load–speed testing showed that the maximum load of the motor was 100 mN@5.8 Vpp. Under a load of 0–100 mN, the driving was stable and the relationship between speed and load was approximately linear, with a thrust-to-weight ratio of 256.

7. Comprehensive performance comparison showed that this multilayer miniature linear ultrasonic motor exhibited excellent large driving force and long-stroke driving capability under micro-size and low-voltage conditions, outperforming several miniature linear ultrasonic motors of the same size.

Figure 3 Voltage–speed test (a) No-load test (b) Load test

Product advantages of Aigtek amplifiers in this application:

1. Wide bandwidth and high voltage slew rate — precisely matches the driving frequency and ensures stable performance within the effective bandwidth

2. High-voltage output and fine gain adjustment — accurately plots the voltage–speed characteristic curve

3. Low distortion and high output stability — ensures driving of capacitive loads such as piezoelectric stacks

【Recommended product】: ATA-2000 series high-voltage amplifier

Figure: ATA-2000 series high-voltage amplifier specifications and parameters