PLL Current Generating Circuit for Voltage-Proportional PTAT Output
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Solution Overview
Problem
Current generating circuits, particularly PTAT current generating circuits used in hall circuits, fail to produce a current that is directly proportional to a reference voltage, which is necessary for certain applications.
Innovation Solution
A current generating circuit comprising a reference clock generating circuit, a phase locked loop circuit, and an output circuit, where the reference clock signal's frequency is proportional to the reference voltage, and the phase locked loop regulates the calibration clock signal to reduce phase difference, controlling the output current based on this phase difference, ensuring it is proportional to the reference voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a typical PTAT current generating circuit is used, then a PTAT current relevant to absolute temperature is generated, but the current is not relevant to reference voltage
Solution Approach 1:
The patent introduces a reference clock generating circuit as an intermediary that converts the reference voltage into a frequency signal. This frequency signal then controls a voltage controlled oscillator in the phase locked loop circuit, which ultimately generates the PTAT current. This intermediary conversion process enables the current to be relevant to both temperature and reference voltage.
Solution Approach 2:
The patent replaces the direct voltage-to-current conversion mechanism with a frequency-based control mechanism. By using a phase locked loop circuit with a voltage controlled oscillator, the system substitutes traditional electrical conversion with a frequency synthesis approach, where the reference voltage controls the oscillation frequency, which in turn controls the PTAT current magnitude.
2Adaptability or versatility
If the PTAT current is made relevant to reference voltage, then the current can be proportional to reference voltage, but the circuit complexity increases
Solution Approach 1:
The phase locked loop circuit serves multiple functions: it generates the calibration clock signal, regulates its frequency based on phase difference, controls the output circuit, and ultimately generates the PTAT current proportional to reference voltage. By making this single circuit block multi-functional, the patent avoids adding separate dedicated circuits for each function, thereby managing complexity while achieving voltage-proportional current.
Solution Approach 2:
The patent combines the reference clock generation, phase locked loop control, and PTAT current generation into an integrated circuit system. The reference clock generating circuit, phase locked loop circuit, and output circuit work together as a unified system where the phase locked loop circuit acts as the central control unit, merging multiple functions into a cohesive structure that achieves voltage-proportional current without excessive complexity.
Data Source
AI summary
A current generating circuit generating a current relevant to a reference voltage. The current generating circuit has a reference clock generating circuit generating a reference clock signal which has a frequency relevant to the reference voltage. The current generating circuit has a phase locked loop circuit generating a calibration clock signal. The phase clocked loop circuit regulates the calibration clock signal so that the phase difference between the calibration clock signal and the reference clock signal is reduced. The current generating circuit has also an output circuit generating an output current according to the phase difference between the calibration clock signal and the reference clock signal.