Transceiver High-Pass Filter Switching for Cross-Coupling Mitigation

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Solution Overview

Problem

Millimeter-wave radar systems experience cross-coupling interference during chirp transmission, leading to ADC saturation and reduced pulse repetition time, which affects the maximum detectable velocity and bandwidth.

Innovation Solution

Temporarily increasing the corner frequency of high-pass filters in the receiver path during transmitter path enablement and decreasing it during transmission to mitigate cross-coupling interference, thereby reducing ADC saturation time and enhancing bandwidth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the corner frequency of the high-pass filter is kept at a low value for normal operation, then the bandwidth and signal quality are improved, but cross-coupling interference from the transmitter path causes ADC saturation during chirp transmission

Engineering Contradiction:

Improvesignal qualityVSAvoidcross-coupling interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The high-pass filter corner frequency is made dynamically adjustable rather than fixed. The controller temporarily increases the corner frequency to a higher value during chirp transmission to block cross-coupling interference, then restores it to the lower normal value for optimal signal quality. This dynamic adjustment resolves the contradiction between maintaining good signal quality and preventing interference.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The corner frequency is increased before the chirp transmission begins (or simultaneously with transmitter enablement), preparing the high-pass filter to block interference in advance. This preliminary action prevents ADC saturation before it occurs, allowing the system to maintain lower corner frequencies for better signal quality during normal operation.

Inventive Principle:

Principle #10Preliminary action

2Speed

If the pulse repetition time is reduced to increase maximum detectable velocity, then the detection capability is improved, but ADC saturation from cross-coupling interference limits the achievable pulse repetition time

Engineering Contradiction:

Improvemaximum detectable velocityVSAvoidADC saturation time

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

The corner frequency is increased before chirp transmission starts, preemptively blocking the cross-coupling interference that would cause ADC saturation. This preliminary action reduces or eliminates the ADC saturation time, allowing the pulse repetition time to be reduced and maximum detectable velocity to be increased.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The harmful ADC saturation effect is extracted and eliminated by dynamically adjusting the high-pass filter corner frequency during transmission. By removing this time loss, the system can achieve shorter pulse repetition times and higher maximum detectable velocities.

Inventive Principle:

Principle #2Taking out (Extraction)

3Device complexity

If a fixed low corner frequency is used in the high-pass filter, then the circuit complexity is minimized, but the system cannot mitigate cross-coupling interference during transmission

Engineering Contradiction:

Improvefilter configurationVSAvoidcross-coupling interference

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

Instead of a fixed corner frequency, the high-pass filter is made dynamically configurable. The controller adjusts the corner frequency between a lower normal value and a higher transmission value based on operational mode. This adds minimal complexity (controllable switch or variable component) but effectively resolves the interference problem.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The corner frequency parameter of the high-pass filter is made changeable based on operational requirements. By switching between different frequency values, the system achieves both low complexity (simple frequency switching) and effective interference mitigation without requiring completely different filter designs.

Inventive Principle:

Principle #35Parameter changes

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 allows for shorter pulse repetition times, increased maximum detection velocity, and improved bandwidth without affecting power consumption or increasing silicon area.

Implementation Method 1

a first high-pass filter; where the controller is configured to: cause a corner frequency of the first high-pass filter to increase from a first value to a second value

Methodology Applied

Scientific EffectHigh-pass filtering: Filter (electronic)

Data Source

PatentUS12566243B2Transceiver circuit and associated cross-coupling interference mitigation method

Publication Date: 2026.03.03 INSTR TEXAS

AI summary

In an embodiment, a system includes: an analog-to-digital converter (ADC); a transmitter path; a receiver path including a first amplifier including: an output coupled to the ADC, and a first high-pass filter; and a controller coupled to the transmitter path and to the receiver path, where the controller is configured to: cause a corner frequency of the first high-pass filter to increase from a first value to a second value, simultaneously or after causing the corner frequency of the first high-pass filter to increase, cause the transmitter path to be enabled, and after a first signal begins transmission in the enabled transmitter path, and during transmission of the first signal in the enabled transmitter path, cause the corner frequency of the first high-pass filter to decrease from the second value to the first value.