On-Chip Inductor Resonator for Flat Broadband RF Response

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Solution Overview

Problem

Existing circuit topologies face challenges in achieving flat frequency response and broad bandwidth while minimizing noise, current consumption, and maintaining linearity, particularly in high-frequency RF circuits used in network nodes like base stations.

Innovation Solution

An on-chip inductor design with a first and second sub-coil in series, connected by a permanent electrical connection, and a resistor in parallel to the second sub-coil, is used to optimize the Q-factor and achieve a flat frequency response and broad bandwidth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If parallel LC resonators are used to achieve high frequency operation and low current consumption, then the Q-factor is improved, but the bandwidth is limited and frequency response becomes non-flat

Engineering Contradiction:

Improvecurrent consumptionVSAvoidbandwidth

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The inductor is divided into two sub-coils (first sub-coil and second sub-coil) with different Q-factors and inductance values. The first sub-coil has higher Q-factor for low-frequency operation, while the second sub-coil has lower Q-factor for high-frequency operation. This segmentation allows the circuit to maintain good frequency response across a broad bandwidth by combining the strengths of both sub-coils.

Inventive Principle:

Principle #1Segmentation

2Speed

If low ohmic broadband load is used to operate at very high frequencies, then the frequency of operation is improved, but noise increases and linearity deteriorates

Engineering Contradiction:

Improvefrequency of operationVSAvoidnoise

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The invention changes the impedance parameter of the load by using a broadband resonator with carefully selected component values. The resonator is designed with specific inductance values (L1, L2) and capacitance values (C1, C2) to achieve a broadband impedance response that maintains high frequency operation while avoiding the noise penalties of low-ohmic loads. The quality factor Q is optimized to balance bandwidth and noise performance.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If operation amplifier based broadband circuits are used to achieve high bandwidth, then the bandwidth is improved, but current consumption increases significantly

Engineering Contradiction:

ImprovebandwidthVSAvoidcurrent consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The invention replaces the active op-amp based broadband circuit with a passive RLC resonator circuit. By substituting the mechanical/electronic active system (op-amp) with a passive resonant system, the circuit achieves broadband operation through resonance rather than through high-gain amplification, thereby dramatically reducing current consumption while maintaining wide bandwidth.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If tuned circuits are used to achieve high Q-factor, then the selectivity is improved, but the frequency response becomes non-flat and bandwidth is limited

Engineering Contradiction:

ImproveselectivityVSAvoidfrequency response flatness

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The invention introduces asymmetry in the resonator design by using two sub-coils with different characteristics (different inductance values and Q-factors) instead of a single symmetric tuned circuit. This asymmetric configuration, combined with carefully selected capacitance values, creates a broadband resonant response that maintains selectivity while achieving a flatter frequency response across a wider bandwidth.

Inventive Principle:

Principle #4Asymmetry

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

The design achieves a flat frequency response and broad bandwidth, reducing noise and current consumption, while maintaining linearity and scalability, suitable for high-frequency RF circuits in network nodes.

Implementation Method 1

The magnetic flux generated by the first and second sub-coils is in the same direction. Since the two sub-coils are electrically connected in series, an additive mutual inductance is created, which increases the total inductance of the inductor.

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS20260018326A1On-chip inductor and broadband amplifier with onchip resonator including the on-chip inductor

Publication Date: 2026.01.15 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Provided is an on-chip inductor for realizing broadband and a flat frequency response. The on-chip inductor includes an inductor coil comprising a first sub-coil and a second sub-coil having mutual inductance, wherein the first sub-coil and the second sub-coil form a permanent electrical connection in series and the second sub-coil is placed inside the first sub-coil on the chip. Furthermore, the on-chip inductor includes terminals connected to the first sub-coil and a resistor connected in parallel to the second sub-coil.