Band-Gap Reference Circuit Mode Control for Image Sensors
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Solution Overview
Problem
Existing band-gap reference circuits for image sensors consume significant power and have long settling times when switching between operational modes, leading to inefficiencies in power management and resumed operations.
Innovation Solution
A band-gap reference circuit with a mode control unit that adjusts its operational mode based on control signals, using a bias generator and error amplifier to reduce power consumption and shorten settling times by switching between ON and low-power modes, with a band-gap loop circuit providing stable voltage references.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the band-gap reference circuit operates in ON mode to provide stable voltage reference, then voltage stability is improved, but power consumption increases significantly
Solution Approach 1:
The band-gap reference circuit dynamically switches between ON mode and OFF mode based on the operational state of the image sensor. The mode control unit receives control signals indicating the sensor's operational mode and accordingly adjusts the bias generator to provide appropriate bias currents, enabling the circuit to adapt its power consumption and voltage reference output dynamically rather than operating continuously in a fixed state.
2Use of energy by moving object
If the band-gap reference circuit is turned off in standby mode to reduce power consumption, then power consumption is reduced, but settling time increases when resuming normal mode
Solution Approach 1:
The bias generator is configured to provide a first bias current when transitioning from standby to normal mode, which is higher than the bias current during normal operation. This preliminary high bias current accelerates the charging of internal capacitors and the stabilization of the voltage reference, thereby reducing the settling time when the circuit resumes operation without requiring the circuit to remain continuously powered.
3Productivity
If the band-gap reference circuit maintains nominal voltage level in standby mode for immediate resumption, then operational readiness is improved, but power consumption increases
Solution Approach 1:
In standby mode, the band-gap reference circuit operates with reduced functionality and lower bias current rather than maintaining full operational voltage level. The mode control unit detects the standby state and adjusts the bias conditions accordingly, providing just enough voltage reference to maintain basic functionality while significantly reducing power consumption, accepting that full operational readiness requires a brief settling period upon mode transition.
Data Source
AI summary
An analog block implemented with a band-gap reference scheme for use in a device includes a mode control unit and a band-gap reference circuit. The mode control unit is configured to generate a mode selection signal associated with the operational mode of the device. The band-gap reference circuit includes a bias generator, an error amplifier, and a band-gap loop circuit. The bias generator is configured to provide a band-gap reference voltage in a first bias state when the device operates in a normal mode or in a second bias state when the device operates in a standby mode. The error amplifier is configured to generate an error voltage according to the bias voltage. The band-gap loop circuit is configured to provide a band-gap reference voltage according to the error voltage. First current flowing through the bias generator in the first bias state is larger than second current flowing through the bias generator in the second bias state.