Segmented LC Delay Line for Wideband Millimeter-Wave Delay Tuning
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Solution Overview
Problem
Existing integrated circuit technologies face challenges in implementing precise wideband programmable time delays and phase shifts, particularly at millimeter wave frequencies, due to the limitations of transmission lines and artificial delay lines, which require significant layout space and are difficult to adjust.
Innovation Solution
The use of segmented inductor loops with switched capacitors and image loops allows for adjustable delay sections that mimic ideal transmission lines, enabling variable delay values while maintaining constant characteristic impedance, thereby improving frequency and group delay characteristics and reducing layout space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transmission lines are used to implement time delay circuits, then the delay is defined by length and phase velocity, but the layout space becomes considerable and adjustment is inherently difficult
Solution Approach 1:
The transmission line is divided into multiple discrete delay sections, each with switchable capacitance values. This segmentation allows the delay to be adjusted in discrete steps while maintaining a compact layout, as each section can be independently controlled without requiring additional physical space proportional to the total delay value.
Solution Approach 2:
The delay line incorporates switchable capacitance elements that allow dynamic adjustment of the delay value. By switching between different capacitance values in each section, the total delay can be programmed to different values without changing the physical layout, enabling adjustable delay in a fixed compact space.
2Speed
If artificial transmission lines with spiral inductors are used, then delay can be achieved at lower frequencies, but the operating frequency is limited by the Bragg frequency and bandwidth is restricted
Solution Approach 1:
The artificial transmission line is divided into multiple discrete sections with switchable capacitance. This segmentation allows the system to operate at frequencies approaching the Bragg frequency by controlling the total electrical length through switching, while maintaining bandwidth by avoiding the low-pass filtering effect of a single long artificial line.
Solution Approach 2:
The capacitance values in each section are made switchable, allowing the electrical length and characteristic impedance of the artificial line to be dynamically adjusted. This enables the system to maintain proper impedance matching and delay characteristics across a wider bandwidth and at higher frequencies near the Bragg frequency.
3Adaptability or versatility
If variable capacitors are used to tune unit delay while keeping fixed inductance, then delay adjustment is achieved, but the characteristic impedance requirement is violated
Solution Approach 1:
The delay line is divided into multiple sections, each with both variable capacitance and corresponding variable inductance. By segmenting the line and adjusting both L and C in each section, the system can change the delay while maintaining constant characteristic impedance, as the ratio L/C remains constant in each section.
Solution Approach 2:
The variable capacitor and variable inductor are combined in each section to work together. By simultaneously adjusting both capacitance and inductance in a coordinated manner, the system achieves delay tuning while maintaining constant characteristic impedance, resolving the contradiction between adjustability and impedance stability.
4Adaptability or versatility
If switchable LC sections are used with image loop inductors, then wideband tunable delays are achieved, but parasitic capacitances degrade performance at millimeter wave frequencies
Solution Approach 1:
The delay line is divided into multiple sections with distributed capacitance values. By segmenting the total delay into smaller sections and distributing the capacitance, the parasitic capacitance effect is reduced relative to the total delay, allowing millimeter wave operation. Each section contributes a small portion of the total delay, making the parasitic effects negligible.
Solution Approach 2:
The design uses more LC sections with smaller individual delay values rather than fewer sections with larger delay values. This partial action approach ensures that the parasitic capacitance in each section is a small fraction of the total capacitance, minimizing its degrading effect on performance at millimeter wave frequencies.
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 approach enhances the operating frequency and group delay characteristics of LC-based artificial lines, offering advantages in die area, insertion loss, and wideband true time delay over traditional methods, enabling efficient implementation of programmable delay lines and phase shifters at millimeter wave frequencies.
Implementation Method 1
An image loop is in electrical communication with the segmented inductor loop. The image loop includes a switch configured to place the plurality of capacitors in one of a high capacitance or a low capacitance state to provide a variable delay value.
Implementation Method 2
The use of segmented inductor loops with switched capacitors and image loops allows for adjustable delay sections that mimic ideal transmission lines
Implementation Method 3
A segmented inductor loop comprising a plurality of segments separated by nodes. A plurality of capacitors are coupled between the segmented inductor loop to provide a plurality of delay sections.
Data Source
AI summary
A switched delay section for an integrated circuit device is disclosed. The switched delay section includes a segmented inductor loop comprising a plurality of segments separated by nodes. A plurality of capacitors are coupled between the segmented inductor loop to provide a plurality of delay sections. An image loop is in electrical communication with the segmented inductor loop. The image loop includes a switch configured to place the plurality of capacitors in one of a high capacitance or a low capacitance state to provide a variable delay value.