Phase-Domain Digitizer Using Delta-Sigma Modulation for Precise Sensing
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Solution Overview
Problem
Existing phase digitizers face challenges in modern nanometer-scale CMOS processes due to non-idealities in analog implementations, such as limited dynamic range, non-linearity, and charge injection, making it difficult to achieve high precision and accuracy in temperature sensing for advanced microprocessors.
Innovation Solution
A phase digitizer with a digital phase-domain delta-sigma modulator that uses a set of reference signals to determine a demodulated phase error, filtered by a digital filter, and sampled by a latch to provide a bit stream representing the phase, allowing for high-resolution digitization of phase shifts associated with thermal-diffusivity-based temperature sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog phase detection circuits are used in nanometer-scale CMOS processes, then the circuit can be implemented with available technology, but the measurement precision deteriorates due to non-idealities such as limited dynamic range, non-linearity, and charge injection
Solution Approach 1:
The patent replaces the analog phase detection circuit with a digital implementation. The digital phase detector uses digital logic circuits (D-flip-flops, XOR gates, counters) to detect phase differences, eliminating the non-idealities of analog circuits such as limited dynamic range, non-linearity, and charge injection. This substitution of digital for analog architecture directly resolves the contradiction by maintaining implementation feasibility in nanometer-scale CMOS while dramatically improving measurement precision and reliability.
2Ease of manufacture
If BJT-based temperature sensors are used, then the sensors can be integrated with microprocessors, but the manufacturing precision deteriorates due to process spread sensitivity
Solution Approach 1:
The patent changes the sensing mechanism from BJT-based voltage/current measurements to ETF-based phase shift measurements. The electrothermal filter converts temperature information into a phase shift of a periodic signal, which is then measured by the digital phase detector. This parameter change from measuring electrical quantities sensitive to process spread to measuring phase shift (which depends on thermal diffusivity and geometry) resolves the contradiction by maintaining ease of integration while dramatically improving manufacturing precision and untrimmed accuracy.
3Measurement precision
If power dissipation in the ETF heater is increased to improve signal strength, then the temperature sensor output signal increases, but the power consumption increases beyond acceptable limits
Solution Approach 1:
The patent replaces the analog signal processing chain with a digital phase detection system. The digital phase detector can accurately measure small phase shifts with high precision without requiring large signal amplitudes. This substitution enables the system to maintain high measurement precision while operating with low power dissipation in the ETF heater, as the digital logic circuits consume minimal power compared to analog amplification requirements.
4Measurement precision
If trimming is applied to improve BJT sensor accuracy, then the temperature sensing precision improves, but the productivity decreases due to increased production test time
Solution Approach 1:
The patent implements a self-calibrating temperature sensor system. The digital phase detector measures the phase shift introduced by the ETF, and the system automatically converts this phase measurement to temperature using the known thermal diffusivity of silicon and the calibrated ETF characteristics. This self-service approach eliminates the need for manual trimming operations during production, maintaining high measurement precision while maximizing production throughput by removing the trimming step entirely.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables highly accurate, low-noise, and precise temperature sensing with reduced non-linearity and quantization noise, suitable for advanced CMOS processes, improving untrimmed inaccuracy and size constraints in microprocessors.
Implementation Method 1
power dissipated in the heater generates heat pulses
Implementation Method 2
heat pulses diffuse through the silicon over a distance (s) between the heater and the temperature sensor
Implementation Method 3
the ETF adds a temperature-dependent phase shift (φ ETF ) to a signal at a particular frequency
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A phase-domain delta-sigma (ΔΣ) modulator in a phase digitizer determines a demodulated phase error based on a phase-modulated frequency signal, in which a carrier frequency is modulated with a fundamental frequency and an associated phase, and a selected one of a set of reference signals, where the demodulated phase error represents a difference between the phase and a reference phase of the selected one of the set of reference signals. Moreover, a digital filter in the phase-domain ΔΣ modulator filters the demodulated phase error. Furthermore, a latch in the phase-domain ΔΣ modulator provides a bit stream by sampling one or more bits of the filtered demodulated phase error, where an average value of the bit stream represents the phase. Next, control logic in the phase-domain ΔΣ modulator selects the one of the set of reference signals.