Bias Generator Startup Circuit Architecture
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Solution Overview
Problem
Existing bias generators face challenges in achieving fast startup and low power consumption while maintaining accuracy, as they often require increased current consumption and longer settling times, especially at higher frequencies, and traditional designs may not provide sufficient current to charge and discharge internal nodes quickly enough for ultra-low power applications.
Innovation Solution
The implementation of a distributed startup circuit architecture with multiple startup blocks controlling PMOS and NMOS transistors individually and sequentially, along with a power switch and timing control signals, allows for precise control of power distribution and reduces startup time by directly energizing critical nodes and minimizing reliance on high-impedance paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a fast startup oscillator is implemented, then startup time is reduced, but inrush current increases and may exceed design budget
Solution Approach 1:
The startup current path is segmented into multiple stages using sequential startup circuits. The first startup circuit provides initial current to critical nodes, while the second startup circuit activates afterward to provide additional current as needed. This segmentation allows controlled current delivery that achieves fast startup without excessive inrush current.
Solution Approach 2:
The first startup circuit performs preliminary action by providing startup current to critical nodes before the main oscillator circuit fully activates. This preliminary current injection jump-starts the oscillation process, reducing the overall startup time while controlling the current profile to avoid excessive inrush.
2Measurement precision
If an elaborate bias generator is used to improve accuracy, then reference voltage and current accuracy improve, but current consumption increases and startup time increases
Solution Approach 1:
The bias generator is segmented into a main bias generator for accurate reference voltage generation and separate startup circuits for fast initialization. The main bias generator uses elaborate circuitry for accuracy but only operates at full power after startup, while the startup circuits provide the necessary current during initialization, separating the accuracy function from the power consumption function.
Solution Approach 2:
The startup circuits operate periodically or temporarily during the startup phase, providing high current only when needed for initialization. Once the oscillator is running, the startup circuits are deactivated, allowing the system to maintain accuracy with minimal current consumption from the main bias generator alone.
3Measurement precision
If an elaborate bias generator is used to improve accuracy, then reference voltage accuracy improves, but control loop settling time increases
Solution Approach 1:
The startup circuits perform preliminary action by providing current to critical nodes before the control loop needs to settle. This preliminary current injection gets the oscillator running and the control loop activated earlier, reducing the overall settling time even though the elaborate bias generator is used for accuracy.
Solution Approach 2:
The system is segmented into startup functions and control loop functions. The startup circuits handle the time-critical initialization, while the elaborate bias generator handles the accuracy-critical reference voltage generation. This segmentation allows both fast settling and high accuracy without one compromising the other.
4Speed
If oscillator frequency is increased to 10MHz, then operating frequency improves, but current consumption increases
Solution Approach 1:
The current delivery system is segmented into startup circuits that provide high current for fast frequency establishment and a main bias generator that provides lower current for sustained operation. The startup circuits enable the oscillator to reach 10MHz quickly, while the main bias generator maintains the frequency with minimal current consumption.
Data Source
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AI summary
Various embodiments relate to a bias generator including: a bias generator circuit; a master startup circuit that applies current to a first node in the bias generator circuit; a second startup circuit that applies current to additional nodes in the bias generator circuit; and a power switch that receives a power from a power supply and that provides power to the bias generator circuit, the master startup circuit, and the second startup circuit.