Oscillation Circuit Variation Sensing for PLL Jitter Control
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Solution Overview
Problem
Existing semiconductor devices face challenges in accurately grasping transistor variations within PLL circuits, which affect jitter values and circuit characteristics, particularly in miniaturized wireless integrated circuits.
Innovation Solution
A semiconductor device and program that utilize a control circuit to operate an oscillation circuit at multiple current values, obtaining frequency information to derive manufacture variation data, allowing for the correction of operation current settings based on frequency differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If microfabrication process is used to suppress chip area increase, then chip area is reduced, but transistor threshold variations and circuit characteristic variations increase
Solution Approach 1:
The patent applies preliminary action by measuring transistor variation characteristics before the PLL circuit operation, using a dedicated measurement circuit that operates independently. The measurement is performed in advance to obtain variation data that is then used for correction during normal operation, allowing the system to compensate for manufacturing variations without affecting the miniaturized design.
Solution Approach 2:
The patent introduces an intermediary measurement circuit and control circuit that acts as a mediator between the manufactured PLL circuit and the final output. This intermediary system measures the actual transistor variations and generates correction signals, effectively decoupling the measurement function from the signal processing function and enabling accurate variation detection in a miniaturized environment.
2Reliability
If gain adjustment circuit and offset adjustment circuit are added to suppress jitter, then jitter is reduced, but the ability to grasp transistor variation values is lost
Solution Approach 1:
The patent segments the circuit functionality by separating the jitter suppression function (performed by gain adjustment and offset adjustment circuits) from the measurement function (performed by a dedicated measurement circuit). This segmentation allows both functions to operate independently and simultaneously, resolving the contradiction between jitter suppression and variation measurement capability.
Solution Approach 2:
The patent introduces a dedicated measurement circuit as an intermediary that specifically measures transistor variation characteristics without being affected by the jitter suppression operations. This intermediary measurement system provides accurate variation data while the separate adjustment circuits handle jitter suppression, allowing both objectives to be achieved simultaneously.
3Measurement precision
If multiple measurement circuits are provided to measure both jitter and transistor variations, then measurement capability is improved, but circuit area and power consumption increase
Solution Approach 1:
The patent applies universality by designing a measurement circuit that can extract multiple types of information (transistor threshold variations and circuit characteristic variations) from the same frequency measurement data. The control circuit performs multiple measurement functions by analyzing frequency differences under different operation current conditions, eliminating the need for separate dedicated circuits for each measurement type.
Solution Approach 2:
The patent uses parameter changes by varying the operation current of the oscillation circuit to different levels and measuring the frequency response at each level. By changing the current parameter and analyzing the frequency differences, the system can extract multiple types of variation information from a single measurement setup, reducing the need for additional circuits.
Data Source
AI summary
A conventional semiconductor device has a problem that acquisition of variation information of circuit elements constructing the semiconductor device is not easy. According to an embodiment, a semiconductor device has a control circuit which makes an oscillation circuit operate by at least two operation current values, obtains first frequency information related to frequency of an output signal corresponding to a first operation current value and second frequency information related to frequency of an output signal corresponding to a second operation current value, and obtains manufacture variation information of a circuit element on the basis of the difference between the first and second frequency information.