DC-Sustained Ultra-Low-Power Oscillator for Frequency Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional high-Q oscillators require high power consumption to maintain frequency stability over process, voltage, and temperature variations, which is not suitable for energy-constrained systems like IoT devices.
Innovation Solution
An ultra-low power oscillator architecture that down-converts the resonator's current to DC, amplifies it, and then up-converts it back to the oscillation frequency, eliminating the need for frequency-dependent minimum transconductance and requiring only a larger feedback resistor than the resonator's resistive loss, while using I/Q paths to maintain zero-phase shift and improve frequency stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional high-Q oscillators are used to maintain frequency stability, then frequency stability is improved, but power consumption increases
Solution Approach 1:
The patent introduces a DC amplifier as an intermediary component that decouples the resonator from direct AC amplification. The resonator's AC signal is converted to DC current, amplified at DC, then converted back to AC. This intermediary DC amplification stage enables ultra-low power operation while maintaining frequency stability, resolving the contradiction between stability and power consumption.
Solution Approach 2:
The patent changes the operating parameter of the amplifier from AC domain to DC domain. By processing the resonator signal at DC where frequency-dependent transconductance requirements are eliminated, the system achieves power consumption as low as 50 pW while maintaining frequency stability. The key parameter change is converting the amplifier operation from frequency-dependent AC amplification to frequency-independent DC amplification.
2Use of energy by moving object
If DC amplification is used instead of AC amplification, then power consumption is reduced, but signal fidelity may be affected
Solution Approach 1:
The patent uses mixers as intermediary components to convert between AC and DC domains. The first mixer converts the resonator's AC signal to DC current for low-power amplification. The second mixer converts the amplified DC signal back to AC at the oscillation frequency. These intermediary conversion stages preserve signal fidelity while enabling ultra-low power DC amplification.
Solution Approach 2:
The patent implements feedback paths that monitor and adjust the DC amplification process to maintain signal fidelity. The feedback mechanism ensures that the DC amplification accurately represents the original AC signal characteristics, preventing distortion and maintaining frequency stability despite the domain conversion.
Data Source
AI summary
An ultra-low power (ULP) oscillator that down-converts the current of a resonator to DC, then amplifies it when its still in DC, followed by up-converting the amplified signal back to the oscillation frequency. The disclosed oscillator eliminates the minimum transconductance (gm) requirement of a Pierce oscillator, by processing the signal at DC. In addition, the circuit only requires the DC amplifier's feedback resistor to be greater than the resistive loss of the resonator, i.e., Rf>Rm.