Research by Alaina Sharp

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Data Acquisition System in Silicon Carbide

Student: Alaina Sharp

Major Professor: Dr. Alan Mantooth

Research Area(s)
Microelectronics

Background/Relevance

  • Silicon carbide is a substance that has been found to be useful for manufacturing products that are needed to perform at high temperatures.
  • A phase – locked loop (PLL) is a control system where the phase of an output signal is related to the phase of an input signal. 

Innovation

  • Determine the characteristics of the noise of the PLL and the VCO in order to determine how the noise is effected when heat is applied, so that  devices with a PLL can function at high temperatures.

Approach

  • Measure VCO by disabling IBIAS and sweeping control from 0V – 15V.
  • Measure the PLL as a whole by comparing a square wave input to the PLL output. 

PLL bare die

schematic of the PLL

Key Results

  • These results show that some noise comes from the VCO, but not all.
  • Some noise was caused by the phase frequency detector, charge pump, resistors and capacitors. 

Conclusions

  • The VCO seems to work correctly although it does put off some noise.
  • It is still unknown if it is the main cause of noise in the system due to lack of time to get sufficient data.
  • The PLL is made up of many components: the phase frequency detector, the charge pump,  the VCO, capacitors and resistors, so there are many different places that the noise could come from.