Reference Voltage Pre-Settling Circuit for Faster Chip Wake-Up
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Solution Overview
Problem
In shrinking semiconductor devices, reference voltage generators like band gap reference circuits and low-dropout regulators face challenges with slow OP-amp output settling times during chip power-up, leading to prolonged power-up times and increased power consumption due to heavy RC loads.
Innovation Solution
An OP-amp output pre-settling scheme is introduced, where a pre-settling circuit actively settles the OP-amp output to a threshold drop before stabilization, incorporating a self-control mechanism for power saving and stability, which can be turned off once internal voltages reach a target level, thereby shortening chip wake-up time and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a pre-settling circuit is added to actively settle the OP-amp output, then the settling time is reduced, but the device complexity increases
Solution Approach 1:
The pre-settling circuit performs preliminary action by actively settling the OP-amp output voltage before the main stabilization phase. The circuit detects when the output voltage reaches a threshold drop and pre-establishes the settled state, eliminating the need for lengthy passive RC time constant settling and reducing overall power-up time.
2Speed
If the pre-settling circuit is kept active continuously, then the settling speed is maintained, but the power consumption increases
Solution Approach 1:
The pre-settling circuit operates periodically rather than continuously. It activates during power-up to perform the settling function, then automatically turns off once the output voltage reaches the threshold drop. This periodic operation maintains fast settling capability when needed while minimizing power consumption during normal operation.
Solution Approach 2:
The circuit incorporates feedback mechanisms that monitor the OP-amp output voltage and detect when it reaches the threshold drop. This feedback control enables the pre-settling circuit to know when settling is complete and when to deactivate, ensuring fast settling performance while avoiding unnecessary continuous operation that would waste power.
3Stability of the object's composition
If the OP-amp output is allowed to settle naturally with heavy RC loads, then the circuit stability is maintained, but the power-up time increases
Solution Approach 1:
The pre-settling circuit performs preliminary action by actively settling the OP-amp output voltage before the main stabilization phase. The circuit detects when the output voltage reaches a threshold drop and pre-establishes the settled state, eliminating the need for lengthy passive RC time constant settling and reducing overall power-up time.
Solution Approach 2:
The pre-settling circuit acts as an intermediary between the OP-amp output and the final stabilization stage. It provides an intermediate settled state with threshold drop that bridges the gap between initial power-up and final stable operation, enabling faster transition while maintaining circuit stability.
Data Source
AI summary
A reference voltage generator includes an input terminal configured to receive an enable signal and an output terminal configured to provide an output signal. A voltage generator circuit is arranged to generate a first output voltage signal, and a pre-settling circuit is arranged to generate a second output voltage. The pre-settling circuit is configured to provide the second output voltage signal at the output terminal in response to the enable signal received at the input terminal, and following a first time period provide the first output voltage at the output terminal.