Analog integrated circuit ultrasonic generator application

Figure 3-34 Schematic diagram of a 200W analog integrated circuit ultrasonic generator Figure 3-34 is a schematic diagram of an integrated circuit ultrasonic generator with a maximum output power of 200W. In the figure, IC1 is a preamplifier (for feedback signal processing), R4, L1, C3 form a band filter, IC2 is a power amplifier, transformer T1 forms an output loop, and transformer T2 forms a feedback signal sampling circuit. Its working principle is: the feedback signal V1 extracted from the transformer T2 (its amplitude varies with the size of the ultrasonic output) is sent to the signal V2 processed by the preamplifier IC1 (its size hardly changes with the size of the ultrasonic output) The potentiometer W2 is sampled, and then filtered by the band-pass filter composed of R4, L1, and C3 to filter the clutter, and then provided to the power amplifier for amplification. The maximum output power of the power amplifier is 200W, and the output signal V0 generated is matched by the output transformer T1 to the ultrasound transducer.

Figure 3-35 and Figure 3-36 are the waveforms of the measured feedback voltages V1 and V2 when the generator is at the minimum power output and at the maximum power output, respectively. It can be seen from Figure 3-32 that the feedback voltage signal V1=0.27V and V2=2.1V at the minimum power output; and as can be seen from Figure 3-36, the feedback voltage signal V1 = 11.0 at the maximum power output V, V2 = 2.56V. Comparing Figure 3-35 and Figure 3-36, it is not difficult to find that during the working process of this integrated circuit ultrasonic generator, the variation range of the feedback signal V1 is between 0.27-11.0V. The variation range of the feedback signal V2 is only between 2.1-2. 56V, which is almost unchanged. In this way, the integrated circuit ultrasonic generator has a wider adjustment range of ultrasonic output power than the above-mentioned transistor circuit ultrasonic generator, and has a more stable ultrasonic output.

As can be seen from Figure 3-37, when the integrated circuit ultrasonic generator outputs the minimum power, the working voltage of the transducer is only 9V. In this way, the integrated circuit ultrasonic generator can be adjusted from almost zero power output. When the transistor circuit ultrasonic generator mentioned above (section 3.3.1) has the minimum power output, the working voltage of the transducer is above 148V (as shown in Figure 3-33).

Figure 3-38 is the output waveform diagram of this integrated circuit ultrasonic generator. As can be seen from the figure, the harmonic distortion (Fig. 3-33) of the analog integrated circuit ultrasonic generator is significantly lower than that of the transistor ultrasonic generator in Fig. 3-31.