BAW Oscillator Series-Resonance Topology for Flicker Noise Suppression
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Solution Overview
Problem
Conventional oscillators suffer from flicker noise degradation at close-in frequency offsets, particularly in applications requiring long-term stability and low drift, such as seismic clocks and GSM satellites, due to up-converted noise in active devices.
Innovation Solution
The implementation of a bulk-acoustic wave (BAW) resonator coupled with an active circuit featuring a series resonance topology, including large bipolar junction transistors, split inductive and resistive degeneration, and a common-mode direct-current biasing inductor, which reduces series capacitive reactance and enhances flicker noise suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional oscillator circuits with active devices are used, then oscillation signal generation is achieved, but flicker noise degrades close-in phase noise performance
Solution Approach 1:
The patent extracts and removes the harmful flicker noise component from the oscillator circuit by using a BAW resonator with series resonance topology, separating the noise generation source from the oscillation signal path, thereby improving close-in phase noise performance
Solution Approach 2:
The patent changes the resonant frequency parameter of the BAW resonator to operate at series resonance rather than parallel resonance, which fundamentally alters the noise characteristics and eliminates the up-conversion of flicker noise to phase noise
2Reliability
If BAW resonator with series resonance topology is implemented, then flicker noise is suppressed, but circuit complexity increases
Solution Approach 1:
The BAW resonator is designed to serve multiple functions simultaneously: it provides frequency determination, amplitude stabilization, and noise filtering in a single component, reducing the need for additional separate circuit elements despite the sophisticated topology
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration achieves ultra-low flicker noise performance at close-in frequency offsets, significantly reducing phase noise and maintaining stability in critical time references.
Implementation Method 1
a bulk-acoustic wave (BAW) resonator having a first BAW resonator terminal and a second BAW resonator terminal
Data Source
AI summary
An oscillator includes: a bulk-acoustic wave (BAW) resonator having a first BAW resonator terminal and a second BAW resonator terminal; and an active circuit coupled to the first and second BAW resonator terminals and having a series resonance topology with: a first transistor; a second transistor; a first resistor; a second resistor; a capacitive network coupled to first and second BAW resonator terminals and to respective current terminals of the first and second transistors; and an inductor having a first inductor terminal and a second inductor terminal, the first inductor terminal coupled to the capacitive network, and the second inductor terminal coupled to ground terminal.