Virtual TDC Quantization Combining for Higher Phase Resolution
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Solution Overview
Problem
Conventional time to digital converters (TDCs) in digital phase-locked loops face limitations in achieving high-resolution phase quantization, leading to significant quantization noise, especially when multiple TDC samples are averaged, which does not effectively reduce noise beyond a certain point due to equal chip area or power constraints.
Innovation Solution
The introduction of a virtual TDC (vTDC) that combines the quantization levels of multiple TDC samples, creating a new 'super-state' that improves phase characterization precision by reducing quantization noise by a factor of √N, offering a more accurate measurement of phase differences between signals, and allowing for lower chip area and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple TDC samples are averaged to improve phase quantization resolution, then measurement precision improves, but quantization noise reduction is limited and device complexity increases
Solution Approach 1:
The patent creates a virtual copy of the TDC system through software simulation, generating a virtual TDC that replicates the quantization behavior of physical TDCs. This virtual copy processes samples without requiring additional physical hardware, thereby improving measurement precision while avoiding the device complexity that would result from adding more physical TDC components.
Solution Approach 2:
The patent replaces the physical mechanical TDC hardware with a software-based virtual TDC model. Instead of using additional physical TDC circuits to generate multiple samples for averaging, the system uses a software simulation that replicates TDC quantization behavior, substituting the mechanical/physical system with a computational one that achieves the same function with less complexity.
2Measurement precision
If multiple TDCs are used to provide concurrent TDC samples within the same REF cycle, then TDC resolution increases, but chip area and power consumption increase
Solution Approach 1:
The patent creates a virtual copy of the TDC system through software simulation, generating a virtual TDC that replicates the quantization behavior of physical TDCs. This virtual copy processes samples without requiring additional physical TDC hardware, thereby achieving higher TDC resolution while avoiding the chip area expansion that would result from adding multiple physical TDCs.
Solution Approach 2:
The virtual TDC software model serves multiple functions: it replicates the quantization behavior of physical TDCs, generates additional sample data for averaging, and operates within the existing hardware footprint. This multi-functional approach allows the system to achieve higher resolution without proportionally increasing chip area.
3Measurement precision
If multiple TDCs are used to provide concurrent TDC samples within the same REF cycle, then TDC resolution increases, but power consumption increases
Solution Approach 1:
The patent creates a virtual copy of the TDC system through software simulation, generating a virtual TDC that replicates the quantization behavior of physical TDCs. This virtual copy processes samples without requiring additional physical TDC hardware, thereby achieving higher TDC resolution while avoiding the power consumption increase that would result from adding multiple physical TDCs.
Solution Approach 2:
The patent replaces the power-intensive physical TDC hardware with a software-based virtual TDC model. The virtual TDC consumes computational resources rather than electrical power proportional to hardware count, enabling higher resolution through virtual sampling without the linear power consumption increase that would accompany additional physical TDC circuits.
4Device complexity
If conventional averaging methods are used to combine TDC samples, then implementation is simple, but quantization noise reduction is limited to a factor of approximately two
Solution Approach 1:
The patent creates a virtual copy of the TDC system that generates additional sample data beyond what physical hardware would provide. This virtual sampling, when combined with physical samples through averaging, achieves greater quantization noise reduction than conventional methods because the virtual TDC effectively multiplies the sample count without proportional hardware increase.
Solution Approach 2:
The patent adds a software dimension to the traditional hardware-based TDC system. By introducing a virtual TDC that operates in the computational domain, the system effectively increases the number of dimensions from which samples can be drawn, enabling more aggressive noise reduction through averaging without the hardware complexity that would normally be required.
Data Source
AI summary
A TDC circuit configured to receive a reference clock (REF) signal and a signal derived from a LO; generate a plurality of digital values indicative of a measured phase difference between the signal derived from the LO and the REF signal, wherein each of the plurality of digital values are determined from a unique set of a plurality of sets of TDC measurement component quantization levels; generate a combined series of quantization levels based on a combination of the plurality of sets of TDC measurement component quantization levels; and determine a combined digital value from the combined series of quantization levels and at least one of the plurality of digital values to generate an output of the TDC circuit. The combined series of quantization levels may be generated by summing simultaneously occurring levels of each of the plurality of sets of TDC measurement component quantization levels together.