Switchable Bias Circuit for Low-Power Always-On Transducers
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Solution Overview
Problem
Electronic devices with transducers like microphones face high power consumption in always-on listening modes due to the need for high-quality bias voltage, which is not efficiently managed, leading to increased energy usage when no trigger or wake word is detected.
Innovation Solution
The circuitry selectively switches between high-quality and low-quality bias voltages based on a mode control signal, using a switch network and regulator circuitry to couple bias voltage output nodes to either a regulated or unregulated voltage source, reducing power consumption by disabling high-power components when not needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a regulated voltage source is used to provide high-quality bias voltage to the transducer, then the sensitivity and performance of the transducer is improved, but the power consumption increases
Solution Approach 1:
The system dynamically switches between regulated and unregulated voltage sources based on operational mode. During listening mode, the unregulated voltage source is used to reduce power consumption while maintaining sufficient transducer sensitivity for wake word detection. When a wake word is detected and the device enters active mode, the regulated voltage source is activated to provide high-quality bias voltage for optimal transducer performance.
Solution Approach 2:
The quality of the bias voltage supplied to the transducer is changed based on operational requirements. The system adjusts the voltage regulation parameter by selecting between two different voltage source configurations: a fully regulated path for high precision applications and an unregulated path for lower power consumption scenarios, thereby optimizing the balance between performance and energy usage.
2Reliability
If the regulated voltage source is always on to maintain high transducer sensitivity, then the transducer performance is improved, but the device power consumption increases
Solution Approach 1:
The voltage supply system is segmented into two independent paths: one through the regulated voltage source and another through the unregulated voltage source. This segmentation allows the system to selectively activate only the necessary path based on operational mode, enabling the regulated voltage source to be powered down during listening mode while maintaining transducer functionality through the unregulated path.
Solution Approach 2:
The regulated voltage source is activated periodically rather than continuously - specifically, it is enabled when a wake word is detected and the device transitions to active mode, and disabled when the device returns to listening mode. This periodic activation reduces overall power consumption while ensuring transducer performance is maintained when needed.
Data Source
AI summary
The present disclosure relates to circuitry for selecting a bias voltage to output at a bias voltage output node of the circuitry. The circuitry comprises a first circuit node configured to receive a first voltage from a first, unregulated, voltage source and a second circuit node configured to receive a second voltage from a second, regulated, voltage source. A switch arrangement configured to selectively couple the bias voltage output node to the first circuit node or the second circuit node is also provided.