Programmable Inductor LC Tank for Wide-Range Frequency Tuning
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Solution Overview
Problem
Conventional LC tank circuits face design tradeoffs when aiming to cover wide frequency ranges, leading to limitations in size, performance, power consumption, and cost, due to the frequency-dependent quality factor and impedance variation.
Innovation Solution
A resonant tank circuit with a programmable inductor and capacitor, where the inductance is switched between sub-bands to optimize frequency operation, reducing impedance variation and enhancing quality factor, thereby minimizing chip area and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-value inductor is used with a variable capacitor to tune operating frequency, then the circuit can operate over a frequency range, but the quality factor varies with frequency and impedance variation increases, leading to design tradeoffs in size, performance, and power consumption
Solution Approach 1:
The patent applies dynamics by making the inductor value adjustable rather than fixed. The inductor array allows switching between different inductance values (L1, L2, L3) based on the operating frequency band. This dynamic adjustment of inductance compensates for frequency-dependent quality factor variations, maintaining stable performance across the tuning range from 3.6 GHz to 4.8 GHz.
Solution Approach 2:
The patent segments the frequency range into multiple sub-bands and assigns specific inductor values to each sub-band. The inductor array divides the total frequency range into segments (e.g., lower band using L1+L2, upper band using L2+L3), allowing optimized quality factor for each segment while maintaining overall frequency coverage.
2Adaptability or versatility
If the frequency tuning range is extended, then the circuit becomes more versatile, but the impedance variation increases, requiring larger component values and greater chip area
Solution Approach 1:
The frequency range is segmented into multiple bands, with different inductor combinations optimized for each band. This allows using smaller inductor values in higher frequency bands, reducing the maximum component size required. The segmented approach enables wide frequency coverage without proportionally increasing chip area.
Solution Approach 2:
The patent changes the inductance parameter dynamically based on frequency band. By switching between different inductor values (L1, L2, L3) and their series combinations, the circuit maintains optimal impedance characteristics across the frequency range, avoiding the need for oversized components that would be required if a single fixed inductor value were used for the entire range.
3Adaptability or versatility
If the frequency tuning range is extended, then the circuit becomes more versatile, but power consumption increases due to larger component values and greater impedance variation
Solution Approach 1:
The dynamic switching between different inductor values allows the circuit to maintain optimal Q-factor and impedance matching across frequency bands. This reduces resistive losses and improves power efficiency at each operating frequency, preventing the power consumption increase that would otherwise result from operating with suboptimal component values over the entire frequency range.
Solution Approach 2:
By segmenting the frequency range and optimizing inductor values for each segment, the circuit achieves efficient operation in each band. This prevents the need to use excessively large inductor values that would be required to cover the entire frequency range with a single configuration, thereby reducing I2R losses and power consumption.
Data Source
AI summary
In one embodiment, a tuning network includes: a controllable capacitance; a first switch coupled between the controllable capacitance and a reference voltage node; a second switch coupled between the controllable capacitance and a third switch; the third switch coupled between the second switch and a second voltage node; a fourth switch coupled between the second voltage node and a first inductor; the first inductor having a first terminal coupled to the fourth switch and a second terminal coupled to at least the second switch; and a second inductor having a first terminal coupled to the second terminal of the first inductor and a second terminal coupled to the controllable capacitance.