Poly-Phase Temperature Sensor for Low-Power Precision Detection
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Solution Overview
Problem
Conventional temperature sensors, particularly those using Wien-bridge band pass filters, suffer from low temperature detection performance and high power consumption due to low output voltage levels and small phase rate of change, making them unsuitable for applications like DRAMs where precise temperature monitoring is critical.
Innovation Solution
A temperature sensor utilizing a poly-phase filter with a higher phase rate of change around the center frequency, reducing power consumption by doubling the output voltage magnitude and improving detection resolution through a poly-phase filter configuration with negative poles and positive zeros, along with a comparator, phase frequency detector, current supply, oscillator, divider, and buffer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Wien-bridge band pass filter is used for temperature detection, then the circuit can operate at resonant frequency, but the output voltage level is low and phase rate of change is small, resulting in low temperature detection performance and high power consumption
Solution Approach 1:
The patent changes the filter configuration from Wien-bridge band pass to poly-phase filter with specific pole-zero placement. The transfer function is modified to have negative poles and positive zeros, which fundamentally changes the phase characteristics and voltage gain, achieving higher phase rate of change and output voltage level for improved temperature detection
Solution Approach 2:
The patent inverts the conventional approach by using a poly-phase filter structure that produces higher output voltage and phase rate of change. Instead of accepting the low voltage/low phase-rate characteristics of Wien-bridge filters, the invention uses the opposite filter topology to achieve superior detection performance
2Use of energy by stationary object
If the output voltage level of the filter is low, then the circuit can be simple, but the sense amplifier consumes more power to compensate for the low voltage level
Solution Approach 1:
The poly-phase filter configuration changes the voltage gain parameter to produce higher output voltage levels. This eliminates the need for high-power sense amplifiers while maintaining or improving detection resolution through the enhanced phase rate of change characteristic
3Measurement precision
If a BJT diode is used for temperature sensing, then the temperature characteristic is accurate, but the device occupies large area making it difficult to use in finer processes
Solution Approach 1:
The patent substitutes the physical BJT diode structure with an integrated poly-phase filter circuit implemented in CMOS technology. This replacement maintains the temperature sensing function while dramatically reducing the device area, enabling compatibility with fine-pitch semiconductor manufacturing processes
Data Source
AI summary
A temperature sensor using a poly-phase filter may include: a poly-phase filter suitable for receiving a divided clock, and having passive elements coupled to have one or more negative poles and one or more positive zeros; a comparator suitable for generating a reference clock by comparing potentials of first and second filter voltages outputted from the poly-phase filter; a phase frequency detector suitable for outputting an up or down signal by comparing the phase of the reference clock to the phase of a comparison clock; a current supply unit suitable for supplying and integrating a charge current under control of the up or the down signal; an oscillator suitable for outputting an oscillation signal; a divider suitable for generating the divided clock and the comparison clock; and a buffer suitable for inverting and non-inverting the divided clock and outputting the inverted and non-inverted divided clocks.