All-pass filter

All-pass filter

Adjusting signal phase


While performing research at UMass Lowell, I worked along side a MEMS project. This project needed to pass two analog signals to the MEMS device to cause parts to move. The two signals needed to be out of phase by varying amounts, and the signals needed to be biased. Providing aid to this project, I designed a simple circuit to be placed between a signal generator and the MEMS device.

Shifting phase was achieved using an all-pass filter. An all-pass filter replicates a waveform and offsets the signal's phase proportionally to resistance. By using a potentiometer in place of the resistor, the phase of the circuit was dynamically varied by adjusting the potentiometer.

Signal bias was manipulated using an external power supply. External power supplied after the phase circuitry corresponded to a final signal voltage offset.

By varying a potentiometer and power supply voltage, the two signals phase and bias were manipulated. The resulting two signals were used to control and test a MEMS device.

All-pass filter
All-pass filter schematic for phase shifting signals

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