# How to amplify a 25khz square wave that goes from -3.3v to +3.3v so that the amplitude is doubled

I have a 3.3v power supply (lithium ion battery) and am using a TI MPS430G2553 chip to generate a 25khz square wave using 2 PWM pins and a push-pull setup. This square wave goes from -3.3v to +3.3v. I need it to produce at least double that voltage (-6.6v to +6.6v) without messing up the 25khz square wave. I will be programatically changing the frequency of this wave from time to time, but will keep it within 1khz of 25khz.

The above circuit is driving a 25khz Piezo Transducer which has a capacitance of 2500pf. The current setup is producing about 80dB. I need 115dB. The datasheet on the Piezo says that at 10v (I'm assuming peak to peak), it will produce 115dB. So if I could double the voltage of the above circuit while maintaining the square wave, I believe I could accomplish my goal.

I have no additional power supply and would like to accomplish this with as few components as possible, for as low cost as possible.

Any recommendations with a circuit example would be GREATLY appreciated.

• An answer to your previous question suggested a transformer with a bridge-driver. You should probably research battery-powered, low-voltage bridges and signal transformers. Commented Jun 21, 2016 at 15:36
• A circuit diagram of your existing push-pull driver would help us. Commented Jun 21, 2016 at 15:37
• There's no circuit. I attach a the 2 terminals from my Piezo Transducer to 2 of the PWM pins on the MSP430G2553 chip. I should probably add a resister between the Piezo and the chip, but don't currently have one. Recommendations are welcome. I'm a software guy, not hardware. I can follow a schematic and assemble a circuit, but I am clueless as to its innerworkings. Commented Jun 21, 2016 at 15:54
• If you are just driving it directly from a MSP430, how are you currently getting it to go down to -3.3V? Commented Jun 21, 2016 at 16:46
• Is it really 2200 nF and not 2200 pF? So what is wrong about the previous answers? Commented Jun 21, 2016 at 16:46