Bandgap Reference Startup Circuit for Stable nA-Level Biasing
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Solution Overview
Problem
Traditional bandgap reference circuits with nA-level working current face instability due to direct addition of resistor series, leading to unstable driving and performance issues, which affects the entire chip.
Innovation Solution
A bandgap reference starting circuit with ultra-low power consumption is designed, incorporating a current generating unit and bias voltage generating units, including MOS transistors and capacitors, to sequentially generate stable bias voltages at nA-level currents, ensuring reliable startup of the bandgap reference circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If resistor series are added directly in the bandgap reference circuit to reduce working current, then power consumption is reduced, but driving stability and working state stability deteriorate
Solution Approach 1:
The patent introduces a starting circuit as an intermediary component between the power supply and the bandgap reference circuit. This starting circuit includes a current mirror circuit that can provide stable driving current during the startup phase, and a discharging circuit that safely discharges stored energy. The intermediary starting circuit allows the main bandgap reference circuit to operate with ultra-low nA-level current while maintaining stability during transitions.
Solution Approach 2:
The starting circuit performs preliminary actions before the bandgap reference circuit operates at ultra-low current. The current mirror circuit pre-charges capacitors and establishes stable voltage levels, and the discharging circuit prepares to safely discharge these capacitors when needed. These preliminary actions ensure that when the bandgap reference circuit starts operating with minimal current, the driving conditions are already stable.
2Use of energy by moving object
If working current is reduced to nA-level for ultra-low power consumption, then power consumption is reduced, but circuit startup reliability deteriorates
Solution Approach 1:
The starting circuit acts as a mediator that bridges the gap between high-reliability startup requirements and ultra-low operating current. During startup, the current mirror circuit provides sufficient current to charge internal capacitors and establish stable operating points. Once startup is complete, the circuit transitions to nA-level operation. The discharging circuit mediates the safe release of stored energy when shutdown is required.
Solution Approach 2:
The circuit dynamically adjusts its operating characteristics. The starting circuit is active during startup and shutdown phases, providing high current when needed. During normal operation, the bandgap reference circuit operates at ultra-low nA-level current. The circuit smoothly transitions between these different operating states, maintaining reliability across all phases.
3Use of energy by moving object
If high impedance is used to reduce working current, then power consumption is reduced, but driving capability deteriorates
Solution Approach 1:
The patent segments the circuit into two functional parts: the starting circuit with high driving capability and the bandgap reference circuit with ultra-low power consumption. The starting circuit contains the current mirror and discharging circuits that provide strong driving capability when needed. The bandgap reference circuit operates with high impedance and nA-level current during normal operation. This segmentation allows each part to optimize for its specific function without compromise.
Solution Approach 2:
The circuit employs periodic action through the alternating operation of the starting circuit and the bandgap reference circuit. During normal operation, the bandgap reference circuit operates at ultra-low current. During startup and shutdown events, the starting circuit activates to provide necessary driving capability. This periodic activation of the high-power starting circuit enables the system to maintain ultra-low average power consumption while preserving driving capability when required.
Data Source
AI summary
A bandgap reference starting circuit with ultra-low power consumption includes a current generating unit and a first bias voltage generating unit respectively connected with a power supply voltage. The current generating unit generates an nA-level current and a starting voltage for the first bias voltage generating unit. The first bias voltage generating unit is started and generates a first bias voltage according to the starting voltage, and output the first bias voltage to a bandgap reference circuit to start up the bandgap reference circuit. The starting circuit can normally start up a bandgap reference circuit of nA level, and has an nA-level working current, thereby reducing power consumption and saving the cost.