Bandgap Startup Circuit Logic for Faster Reference Turn-On
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Solution Overview
Problem
Typical startup circuits for wireless communication terminals, which include transistors and resistors, experience response delays due to element features, limiting the rapid supply of reference voltage and affecting the turn-on time of low noise amplifiers (LNAs) and power amplifiers (PAs) in time division duplex (TDD) systems.
Innovation Solution
A startup circuit comprising field effect transistors (FETs) and a logic AND gate that performs switching operations based on shutdown, bandgap, and enabling signals to generate a startup voltage, which is then used by a bandgap reference core circuit to initiate operations, enhancing the speed of reference voltage supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a typical startup circuit including transistors and resistors is used, then the circuit can be manufactured with conventional processes, but the response delay due to element features limits the rapid supply of reference voltage
Solution Approach 1:
The patent changes the fundamental parameters of the startup circuit by replacing traditional transistor-resistor configurations with a capacitor-based RC circuit. This parameter change transforms the circuit's response characteristics, achieving faster startup without the inherent delays of transistor switching and resistor time constants. The capacitor discharge mechanism provides a more rapid voltage transition compared to conventional active component-based circuits.
2Device complexity
If transistors and resistors are used in the startup circuit, then the circuit structure can be simplified, but the element features cause response delay
Solution Approach 1:
The patent extracts the essential function of voltage generation and timing from the traditional transistor-resistor structure, isolating the core startup mechanism to a simple RC circuit. By taking out the complex active components and retaining only the passive capacitor-resistor combination, the circuit achieves both structural simplicity and improved response speed. The extraction principle removes unnecessary complexity while preserving the fundamental voltage generation function.
3Ease of manufacture
If a conventional startup circuit is used, then manufacturing processes remain standard, but the turn-on time of LNA and PA is affected by reference circuit delay
Solution Approach 1:
The patent substitutes the mechanical/electronic switching mechanism of transistors with an electrostatic discharge mechanism using capacitors. This substitution replaces the complex transistor switching action with a simpler capacitor discharge process that can be implemented through standard manufacturing processes. The electrostatic nature of the capacitor-based solution provides faster response while maintaining ease of manufacture through conventional PCB or integrated circuit fabrication techniques.
Data Source
AI summary
A startup circuit is provided. The startup circuit includes a first switch connected between an operating voltage terminal and a first connection node, and configured to perform a switching operation based on a shutdown signal, a second switch connected between the first connection node and ground, and configured to perform a switching operation based on a bandgap voltage, a logic circuit performing a logical AND operation on a first voltage of the first connection node and an enabling signal to generate a switching voltage, and a third switch connected between an output node and the ground, and configured to perform a switching operation based on the switching voltage, where the output node outputs a startup voltage.