LC Oscillator Wirebond Configuration for Frequency Increase
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Solution Overview
Problem
LC oscillators in RFIC designs face limitations in achieving high frequency signals due to the constraints of inductance values in wirebonds, which restrict the maximum frequency of operation and are sensitive to assembly errors and physical dimensions.
Innovation Solution
The introduction of a third wirebond with specific orientation relative to the first and second wirebonds, forming a configuration that reduces the overall inductance, allowing for increased maximum frequency and improved phase noise performance, while being less sensitive to assembly variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional wirebond configurations are used to connect differential outputs to ground, then the structure is simple and easy to manufacture, but the inductance is high which limits the maximum operating frequency
Solution Approach 1:
The single ground connection path is segmented into multiple parallel wirebonds (first and second wirebonds) connecting each differential output to ground. This segmentation reduces the effective inductance by providing multiple current paths, thereby increasing the maximum operating frequency of the oscillator.
Solution Approach 2:
A third wirebond is added specifically between the differential outputs to create a localized inductance reduction path. This third wirebond has specific orientation relative to the first and second wirebonds, creating a configuration where the inductances combine to give a lower equivalent inductance L'' than the traditional configuration.
2Speed
If wirebond inductance is reduced to increase frequency, then the maximum frequency increases, but the system becomes more sensitive to assembly errors and physical dimension variations
Solution Approach 1:
The invention changes the topological configuration of the wirebond network rather than simply reducing individual wirebond lengths. By adding the third wirebond between differential outputs and orienting it perpendicular to the first and second wirebonds, the equivalent inductance is reduced to L'' while creating a more robust configuration that is less sensitive to assembly variations.
Solution Approach 2:
The third wirebond is positioned asymmetrically with its plane perpendicular to the planes of the first and second wirebonds. This asymmetric orientation minimizes mutual inductance effects and creates a configuration where the equivalent inductance is less sensitive to small variations in wirebond placement and orientation during assembly.
3Speed
If the third wirebond is added with specific orientation, then the equivalent inductance is reduced and frequency increases, but the manufacturing process becomes more complex
Solution Approach 1:
The third wirebond is oriented in a different spatial dimension (plane) compared to the first and second wirebonds. By positioning the third wirebond's plane perpendicular to the planes of the other two wirebonds, the invention achieves inductance reduction through three-dimensional spatial arrangement rather than merely adjusting wirebond lengths, making the solution adaptable to various manufacturing tolerances.
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 a maximum frequency increase by a multiplicative factor of up to sqrt(3) compared to traditional designs, enhancing flexibility in frequency selection and reducing the impact of assembly errors on frequency stability.
Implementation Method 1
The third wirebond can define a plane that is approximately perpendicular to each of the first and second so as to yield a reduced mutual inductance between the third wirebond and the parallel first and second wirebonds
Implementation Method 2
An LC circuit can reach a resonance state having a frequency
Data Source
AI summary
Disclosed are circuits and methods for increasing an output frequency of an inductance-capacitance (LC) oscillator. In some embodiments, the LC oscillator can be implemented as a voltage-controlled oscillator (VCO) having differential outputs. When the VCO is implemented on a die, wirebond connections from the outputs to a ground results in an effective inductance that impacts a maximum frequency associated with the VCO. An electrical connection such as a wirebond between the differential outputs yields a reduction in the effective inductance thereby increasing the maximum frequency. In some embodiments, the wirebond between the differential outputs can be configured so that its contribution to mutual inductance is reduced or substantially nil.