Area efficient, low power and flexible time digitizer
AssigneeTexas Instruments Incorporated
InventorsBaher Haroun, Heng-Chih Lin, Tim Foo
Life of this patent
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Abstract
A non-linear time digitizer delay chain and a respective lookup table for converting the phase error into a digital code together prevent a phase error pulse from saturating the delay chain, even when the input frequency varies by orders of magnitude. By using a non-linear T2D delay chain along with a corresponding lookup table, the phase error pulse associated with a digital phase lock loop (PLL) can be measured and represented in more meaningful and accurate ways that that achievable when using a conventional T2d circuit to convert the phase error into a digital code. The lookup table implementation allows an additional degree of freedom for designers to apply a transfer function to the digital code measured by the T2D.
Claims19
A time digitizer system comprising:
- a delay chain configured to generate a logarithmic code in response to a pulse of a specific time width;
- and
- a look-up table comprising desired transfer function data such that the logarithmic code is modified by the desired transfer function data to provide a final code.
A time digitizer system comprising:
- a delay chain configured to generate a logarithmic phase error code in response to a pulse of a specific time width corresponding to a phase difference between a reference clock and a feedback clock;
- and
- a look-up table comprising desired transfer function data such that the logarithmic phase error code is modified by the desired transfer function data to provide a final error code.
A time digitizer system comprising:
- a delay chain having a first transfer function and configured to generate a phase error code in response a phase error pulse;
- and
- a look-up table comprising data associated with a second transfer function, such that the phase error code is modified by the second transfer function data to provide a final phase error code.
A method of encoding a phase error pulse, the method comprising the steps of:
- generating a phase error pulse in response to a difference between a reference clock and a feedback clock;
- generating an encoded phase error code via a time digitizer in response to the phase error pulse;
- and
- modifying the encoded phase error code via look-up table data to provide a final phase error code.
Dependencies are inferred from the claim text.