Feedforward Bias Circuit for Fast Stable Power-On Reset
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Solution Overview
Problem
Existing reference voltage generation circuits struggle to generate a stable and accurate reference voltage quickly when supply voltages from energy harvesting technologies experience steep variations, making it difficult to maintain a constant reference voltage at appropriate timing.
Innovation Solution
A bias circuit configuration using a feedforward approach with N-type transistors and resistive devices to generate a bias voltage and current independently of supply voltage fluctuations, allowing for rapid stabilization during steep voltage increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a feedback circuit is used to generate a reference voltage, then the reference voltage can be generated with high accuracy, but the circuit cannot respond quickly to steep voltage variations during boot-up
Solution Approach 1:
The patent applies preliminary action by generating the reference voltage before the supply voltage has fully stabilized. The circuit is designed to operate correctly even when the supply voltage is still rising, eliminating the need to wait for voltage stabilization before reference voltage generation begins.
Solution Approach 2:
The patent employs feedback mechanisms where the reference voltage generation circuit monitors the supply voltage status and adjusts its operation accordingly. The circuit detects when the supply voltage reaches appropriate levels and coordinates the activation of various circuit blocks to ensure accurate reference voltage generation during the boot-up process.
2Measurement precision
If a feedback circuit is used to generate a reference voltage, then the reference voltage can be generated with high accuracy, but the circuit complexity increases
Solution Approach 1:
The patent divides the voltage generation system into separate functional blocks: a supply voltage generation unit, a reference voltage generation unit, and control circuits. Each block operates independently with defined interfaces, allowing the reference voltage circuit to be designed for high accuracy without requiring the entire system to be redesigned, thus managing complexity through modular segmentation.
Solution Approach 2:
The patent introduces intermediate control circuits and status signals that mediate between the supply voltage generation and reference voltage generation. These intermediary elements coordinate the boot-up sequence and ensure proper timing without requiring direct complex feedback connections between all circuit blocks, thereby reducing overall system complexity.
Data Source
AI summary
A bias circuit includes a first resistive device connected between a power supply node to supply a supply voltage and a first node, a first N-type transistor diode-connected between the first node and a ground, a second N-type transistor, a second resistive device connected between a second node and a third node, and a third N-type transistor connected between the third node and the ground to implement a current source. The second N-type transistor has a drain connected to the power supply node, a source connected to the second node to output a bias voltage, and a gate connected to the first node.