Charge Pump Circuit With Temperature-Dependent Bias Current
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Solution Overview
Problem
Conventional charge pump circuits require a large chip surface area due to high power losses and heating issues, which are exacerbated by the need for constant current sources to reduce electromagnetic interference.
Innovation Solution
Implementing a charge pump circuit with a temperature-dependent bias current, which allows for a smaller transistor size by reducing current requirements as temperature increases, thereby minimizing surface area and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If constant current sources are used to reduce electromagnetic interference, then electromagnetic emissions are reduced, but chip surface area increases due to large transistor sizes required to limit heating
Solution Approach 1:
The patent applies dynamics by transitioning from static constant current sources to dynamic switched current sources. The current mirrors switch between different current sources based on the operational phase of the charge pump, allowing the circuit to adapt its current characteristics dynamically. This enables reduced electromagnetic emissions while using smaller transistors that switch rapidly rather than continuously dissipating power.
Solution Approach 2:
The patent implements periodic action through the phase-dependent switching of current mirrors. During the first phase, a first current mirror provides current to reduce emissions from the first switched current source. During the second phase, a second current mirror provides current to reduce emissions from the second switched current source. This periodic activation of current mirrors reduces their duty cycle and allows smaller transistor sizes.
2Temperature
If larger transistors are used to limit heating from high power losses, then thermal management is improved, but chip surface area increases
Solution Approach 1:
The patent uses dynamic switching of current mirrors to reduce continuous power dissipation. Instead of large transistors continuously conducting current to manage heat, the current mirrors switch rapidly between phases, reducing the average current and power loss. This allows smaller transistor sizes while maintaining acceptable thermal characteristics through reduced duty cycle operation.
3Object-generated harmful factors
If switched currents are converted to direct currents using constant current sources, then electromagnetic interference is reduced, but power losses increase requiring larger transistors
Solution Approach 1:
The patent replaces static constant current sources with dynamic switched current sources controlled by phase signals. The current mirrors activate only during their respective phases rather than continuously, reducing the average current and associated power losses. This dynamic approach maintains the current conversion function while significantly reducing energy dissipation.
Solution Approach 2:
The patent employs periodic action through phase-dependent current mirror activation. The first current mirror operates during the first phase and the second current mirror operates during the second phase, creating a periodic switching pattern. This reduces the continuous power loss associated with constant current sources while maintaining the ability to convert switched currents to direct currents for electromagnetic interference reduction.
Data Source
AI summary
A charge pump circuit is provided, in which a charge pump is supplied with a temperature-dependent bias current, in particular a bias current that decreases with temperature.