Auxiliary Startup Circuit Shutdown for Low-Power Bias References
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Solution Overview
Problem
Existing auxiliary startup circuits for circuits with 'degenerate' bias points face challenges in minimizing power consumption after the circuit is powered on, especially in low-power-consumption designs.
Innovation Solution
The system incorporates a second switch transistor M2 connected to a switch control signal SLEEP, allowing the auxiliary startup circuit to be turned off after the circuit is powered on, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the second resistor R2 is increased to reduce the current I1 and minimize power consumption, then the power consumption of the auxiliary startup circuit is reduced, but the voltage at the VN point becomes too much lower than the working voltage VDD, which may cause the first PMOS transistor PM1 to be turned on mistakenly
Solution Approach 1:
The patent introduces a dynamic control mechanism using a control transistor (second PMOS transistor PM2) that adjusts the resistance of the second resistor R2 based on circuit operating conditions. The gate voltage of PM2 is dynamically controlled to modify the effective resistance, allowing the circuit to adapt between different resistance states to prevent PM1 from turning on mistakenly while maintaining power consumption reduction
Solution Approach 2:
The patent changes the resistance parameter of the second resistor R2 dynamically by introducing a control transistor PM2 whose gate voltage can be adjusted. This parameter change allows the resistance to be optimized for different operating phases: higher resistance for power consumption reduction and lower resistance for ensuring sufficient voltage at VN point to prevent false triggering of PM1
2Reliability
If the auxiliary startup circuit functions continuously to ensure reliable startup, then the circuit can always assist in getting rid of the bias point, but the power consumption of the auxiliary startup circuit increases
Solution Approach 1:
The patent implements periodic action by controlling the auxiliary startup circuit to operate only during the startup phase. The control transistor PM2 is enabled temporarily during power-on to assist startup, then disabled after startup completion. This periodic operation ensures reliable startup assistance while minimizing power consumption during normal operation
Solution Approach 2:
The patent applies preliminary action by preparing the auxiliary startup circuit to activate only when needed (during startup). The control mechanism is designed to enable the auxiliary circuit before startup is needed and disable it after startup is complete, ensuring the circuit performs its startup assistance function reliably while avoiding continuous operation and excessive power consumption
Data Source
AI summary
This application discloses a system for turning off power consumption of an auxiliary startup circuit. An oscillator generates a switch control signal based on a reference current output by a circuit to be started up to generate a working clock of a switch control signal generation circuit after the circuit to be started up works normally. After fixed clock signal counting, the switch control signal generation circuit outputs a switch control signal to control power consumption of normally open current of the auxiliary startup circuit to be turned off. At the same time, the switch control signal generation circuit stops counting the clock. This application can assist the circuit to be started up having a “degeneracy” bias point to power on normally, and can also turn off the power consumption of the auxiliary startup circuit after the circuit to be started up is powered on.