CAN YOU PROVIDE SOME EXAMPLES OF SUCCESSFUL PLL DESIGN CAPSTONE PROJECTS DONE BY STUDENTS

A phase-locked loop (PLL) frequency synthesizer design was completed by a student as their senior capstone project. The purpose of the project was to design a fractional-N PLL frequency synthesizer that could generate frequencies from 1-10 GHz with 1 MHz resolution. The PLL was designed to target an FPGA technology and optimize for low power consumption and small silicon area usage.

The student’s design utilized a charge pump based phase frequency detector (PFD) with current mode logic. A 5-bit prescaler and 12-bit digital controlled oscillator (DCO) were used to achieve the required frequency resolution. A 1 GHz VCO core was selected from a vendor IP library and properly interfaced to the DCO tuning input. Digital logic was designed to implement fractional-N frequency division with a modulus-N value up to 212. Extensive simulations were run in both post-layout and behavioral modes to verify the PLL could lock across the entire frequency range within the desired acquisition and settling times.

Power optimization techniques such as clock gating were applied throughout the design. Post-layout simulations showed the synthesized PLL core consumed under 100mW when locked. The student verified their design met all required specifications by fabricating an ASIC test chip. Measurements of the fabricated PLL showed it could successfully lock to any 1 MHz increment between 1-10GHz with acquisition times under 10us and steady state frequency drifts less than 1 ppm. The student’s project demonstrated an innovative fractional-N PLL design that achieved excellent frequency resolution and accuracy while optimizing for low power.

Read also:  WHAT ARE SOME POTENTIAL CHALLENGES THAT STUDENTS MIGHT FACE WHEN IMPLEMENTING CAPSTONE PROJECTS IN THE OR

Another successful capstone project involved designing a charge pump PLL for clock and data recovery in serial data links. The student focused their project on high-speed interfaces operating at multi-gigabit data rates. They designed a charge pump PLL that recovered clocks from 4.25Gbps serial data streams. The core specifications for their PLL design were:

Frequency range: 3.5-5Gbps
Acquisition range: ±100MHz
Settling time: <250ns Reference frequency: 25MHz Technology: 45nm CMOS The student's PLL design utilized a multi-modulus divider in the feedback path to allow for integer-N operation across the entire frequency range. Their phase frequency detector and charge pump circuits were optimized for high-speed operation by employing current mode logic, short critical paths, and limiting parasitic capacitances. Feedback path filters were carefully sized to provide sufficient damping while minimizing phase margin degradation.

Read also:  WHAT ARE SOME POTENTIAL LIMITATIONS OF USING SELF REPORT MEASURES IN THIS STUDY
Extensive simulations and pre-layout analysis were done to verify lock acquisition and tracking capabilities. Post-layout simulations showed the design could successfully recover clocks from data with bit error rates less than 1E-12. The design was fabricated as an independent verification vehicle through a silicon foundry.Chip measurements validated the PLL reliably locked onto data streams up to 4.5Gbps, meeting and exceeding the project goals and specifications. This successful student project demonstrated an innovative high-speed PLL design approach for serial data recovery applications. Another senior capstone project involved developing a low power fractional-N PLL for wireless transceiver applications. The student designed a wireless transmitter requiring a frequency synthesizer to generate output frequencies from 2.4-2.5GHz with 500kHz resolution to support protocols such as Bluetooth. Key specifications for their fractional-N PLL design included: Frequency range: 2.4-2.5GHz Frequency resolution: 500kHz Reference frequency: 25MHz Settling time: <500ns Technology: 65nm CMOS Power consumption: <100mW The student implemented a 7-bit delta-sigma modulator to realize fractional-N frequency division. An on-chip VCO was designed centered at 2.45GHz along with amplitude control circuitry. Feedback loops were optimized through pole-zero alignment techniques. Logic-based frequency switching was implemented to quickly switch output frequencies with glitch-free operation.
Read also:  CAN YOU PROVIDE AN EXAMPLE OF HOW THE GITHUB PROJECT BOARDS WOULD BE USED IN THIS PROJECT
An ASIC was fabricated in a Silicon On Insulator process. Measurement results showed the synthesized fractional-N PLL core consumed only 75mW while meeting the frequency resolution specification across the entire tuning range. Settling times were consistently below 400ns. The student demonstrated extensive characterization of frequency switching performance, phase noise, and amplitude control loop dynamics. This successful PLL design project showed innovation in realizing a low power fractional-N frequency synthesizer suitable for wireless transmitter applications. These examples demonstrate a few of the many successful PLL design projects completed by electrical engineering students as their capstone projects. Common themes included optimizing for power, speed, and accuracy while meeting rigorous specifications. Through innovative circuit techniques and verification planning, students were able to synthesize high performance PLL cores suitable for applications such as frequency synthesis, clock recovery, and wireless transmitters. These capstone projects exemplified the systems engineering skills gained through hands-on design experiences of realizing complex analog blocks like PLLs from concept to implementation.

Leave a Reply

Your email address will not be published. Required fields are marked *