Electronic – What do you call a 1:3 turn ratio transformer

I need a small surface mount or slightly larger transformer with a 1:3 turn ratio that will triple my voltage from 3.3 to 9.9 volts.

I have been literally searching the internet for such a thing and cannot find one. Can somebody please tell me what the heck you call the thing so that you can find it when searching for transformers?

I'm going to be running 2 PWM lines through it from an MSP430 controller and the PWMs will be doing a push-pull so that they generate +3.3 => -3.3 volts for a total of 6.6v peak to peak. They are also generating a nice 25khz square wave.

Anyway, I want to attach those 2 wires to the little transformer and have a nice pretty square wave coming out at around 18 volts peak to peak.

This needs to be very small. Preferably less than a centimeter square.

What do you call this thing and Where can I order one?

UPDATE (Clarification):

The purpose of this circuit is to drive a Piezo Transducer at 25khz and have it produce 110dB. In order to do this, I need a minimum of 10v Peak to Peak.

I am using an MPS430 controller which has 2 PWM pins. I'm using a push-pull algorithm to have those 2 pins produce opposite waveforms. So, I have 2 square waves being generated opposite of each other. This gives me +3.3v -> -3.3v or 6.6 volts Peak to Peak. The max voltage for the Piezo is 20, so I would like to double or triple my output voltage. One suggestion was a 3:1 Transformer. That seemed like the easiest way to do it. I am open to using whatever solution works, there have also been other recommendations. However, I would like to accomplish this with parts that do not exceed a total of $2.00. Also, the parts must be very small. This circuit needs to go on a board that is .75" x 1.5". It needs to fit in an enclosure that will attach to a dog's collar. The only power for the entire device is a small 3.7v rechargeable lithium battery.

Thanks !!