A Crystal-Based Low-Voltage All-Digital Programmable Ring Oscillator

We have designed and implemented a flexible programmable multi-channel digitally-controlled oscillator (MDCO) on an Altera MAX9400 Complex Programmable Logic Device (CPLD) chip. Based on elaborate experiments with the system, we have developed techniques by which to improve its linearity, resolution and stability in an improved MDCO design. This new architecture is programmable to oscillate from 0 Hz to a maximum that is determined by the oscillator master processing clock and the technology limitations. As crystal-based-programmable-delay cells (CBPDC) control its dominant propagation delay, the oscillator frequency thermal drift and jitter are reduced.