Voltage Generator Circuit with Dynamic Ramp Slope Control
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Solution Overview
Problem
Conventional resistor-ladder ramp generator circuits are limited in increasing the slope of the ramp wave and A/D conversion time increases with the number of bits, restricting the variable range and accuracy of voltage waveform resolution.
Innovation Solution
A voltage generator circuit with a resistor ladder and switch control circuit that adjusts the number of simultaneously ON switches to finely control the resistance value and slope of the ramp wave, allowing for higher resolution and accuracy without increasing the number of resistors or switches, and dynamically changing the slope to prevent A/D conversion time increase with increased bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of bits for A/D conversion is increased, then the resolution and accuracy of voltage waveform are improved, but the A/D conversion time increases
Solution Approach 1:
The patent applies dynamics by making the ramp wave slope variable rather than fixed. The switch control circuit dynamically adjusts the number of simultaneously ON switches to change the effective resistance, thereby varying the ramp slope during operation. This allows the system to adapt the conversion speed to the required resolution, preventing conversion time from increasing proportionally with bit depth.
Solution Approach 2:
The patent changes the resistance parameter by controlling different numbers of switches to be simultaneously ON. By varying the number of active switches, the effective resistance in the resistor ladder circuit changes, which directly affects the ramp wave slope. This parameter change enables high-resolution conversion without requiring proportionally longer conversion times.
2Speed
If the slope of the ramp wave is increased to reduce A/D conversion time, then the conversion speed is improved, but the voltage applied across the resistor ladder circuit must exceed supply voltage which is not allowed
Solution Approach 1:
The patent uses dynamics by controlling the number of simultaneously ON switches to adjust the effective resistance. This dynamic resistance adjustment allows the ramp slope to be increased without exceeding the supply voltage constraint, because the slope control is achieved through resistance modulation rather than voltage escalation.
Solution Approach 2:
The patent changes the resistance parameter to control ramp slope. By adjusting which switches are ON, the effective resistance changes, which in turn changes the ramp wave slope according to the relationship slope = V/(R*C). This allows slope adjustment while maintaining voltage within supply limits.
3Adaptability or versatility
If more resistors and switches are added to increase the variable slope range, then the slope adjustment range is improved, but the device complexity increases
Solution Approach 1:
The patent applies merging by controlling multiple switches to be simultaneously ON. Instead of requiring separate resistors for each slope setting, multiple switchable resistors are combined into a single controlled network. The switch control circuit manages the simultaneous state of multiple switches to achieve various effective resistance values, reducing overall device complexity while expanding slope adjustment range.
Solution Approach 2:
The resistor ladder circuit with switch control serves multiple functions: it provides both the resistive division function and the slope control function. The same set of switches that select resistor taps also controls the effective resistance for slope adjustment, eliminating the need for separate control mechanisms and reducing device complexity.
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
Enables arbitrary adjustment of the ramp wave slope to higher values while maintaining high accuracy and preventing A/D conversion time increases, even with increased bits, without adding resistors or switches, thus enhancing the performance of image sensors and A/D converters.
Implementation Method 1
a resistor ladder circuit configured to receive a predetermined voltage or a predetermined current, and to generate a plurality of reference voltages different from one another
Implementation Method 2
control on-off states of the plurality of switches so that k (k is an integer greater than or equal to one) switches among consecutive (k+1) switches out of the plurality of switches are set to an ON state
Data Source
AI summary
A resistor-ladder voltage generator circuit is provided, which controls so that k switches among consecutive (k+1) switches out of a plurality of switches connected to the resistor ladder circuit are simultaneously set to an ON state, and which temporally switches the value of k. This allows voltage waveforms having different slopes to be arbitrarily obtained, ranging from a voltage waveform having a small slope to a voltage waveform having a large slope, thereby improving the resolution of a generated voltage waveform without increasing the numbers of resistors and switches, while A/D conversion time is not increased even if the number of bits is increased. In addition, by using this voltage generator circuit as a ramp generator circuit, and by dynamically switching the slope of the ramp wave, acceleration of an image sensor is achieved.