Bias Current Generation Circuit for Cold Temperature Settling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The settling behavior of amplifier circuits degrades at cold temperatures when using proportional to absolute temperature (PTAT) bias current, leading to increased settling time and reduced performance.
Innovation Solution
A bias current generation system that combines a PTAT current source with a constant current source, where the constant current is added to the PTAT current in cold temperatures to improve settling behavior without increasing power consumption at room temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If PTAT bias current is used to maintain settling behavior at hot temperatures, then settling time is improved at high temperatures, but settling time increases at cold temperatures
Solution Approach 1:
The patent changes the parameter of bias current by combining two different current sources with opposite temperature dependencies. The first current source provides PTAT current (increases with temperature) while the second provides CTAT current (decreases with temperature). By adjusting their ratio, the total bias current's temperature coefficient is optimized to maintain consistent settling time across temperature ranges.
Solution Approach 2:
The patent creates a composite bias current system by merging two distinct current sources with complementary temperature characteristics. This composite approach allows the system to leverage the advantages of both PTAT and CTAT currents, achieving stable settling behavior across wide temperature variations that neither current source could achieve alone.
2Loss of time
If constant current is added to PTAT current to improve cold temperature performance, then settling behavior is improved at cold temperatures, but power consumption increases at room temperature
Solution Approach 1:
The patent implements a dynamic bias current system where the contribution of each current source varies with temperature. At cold temperatures, the CTAT current component dominates to improve settling time. At room temperature, the PTAT current component dominates to minimize power consumption. This dynamic adjustment allows the system to optimize for different performance criteria at different temperatures.
Solution Approach 2:
The patent changes the effective parameter of bias current magnitude by using temperature-dependent current mirroring ratios. The current mirror circuits are designed to automatically adjust the relative contribution of each current source based on temperature, thereby changing the total bias current parameter to match optimal requirements for each temperature condition.
Data Source
AI summary
Bias current generation systems are disclosed. In one embodiment, a bias current generation system comprises a proportional to absolute temperature (PTAT) current source generating a PTAT current, a constant current source generating a constant current, a first current mirror forwarding the PTAT current, a second current mirror forwarding an adjusted current, where the adjusted current is the constant current subtracted by the PTAT current if the constant current subtracted by the PTAT current is greater than zero or the adjusted current is zero if the constant current subtracted by the PTAT current is less than zero, a third current mirror forwarding the adjusted current and a fourth current mirror forwarding a bias current generated by subtracting the PTAT current from the adjusted current.