Intermediate Frequency Amplifier High-Pass Filtering for Radar Blockers
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Solution Overview
Problem
Radar systems face a high-power, low-frequency blocker signal due to couplings between transmitter and receiver antennas, leading to slow settling of intermediate frequency signals, which wastes samples and prevents fast chirp repetitions for detecting fast-moving targets and wastes radar frequency bandwidth.
Innovation Solution
A radar system with a digital ramp generator, oscillator, power amplifier, low-noise amplifier, mixer, and intermediate frequency amplifier (IFA) that includes a configurable high-pass filter with adjustable cutoff frequencies, allowing faster settling of the IFA output by filtering out the blocker signal during the initial portion of the chirp signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a high-pass filter is used to remove the blocker signal, then the blocker signal is filtered out, but the settling time of the intermediate frequency signal increases
Solution Approach 1:
The patent applies dynamics by making the high-pass filter cutoff frequency adjustable rather than fixed. The filter transitions from a higher cutoff frequency during the initial portion of the chirp signal to a lower cutoff frequency during the latter portion, allowing the system to adapt its filtering characteristics over time to resolve the contradiction between blocker rejection and settling time.
Solution Approach 2:
The patent changes the parameter of the high-pass filter cutoff frequency over time. By dynamically adjusting the cutoff frequency from high to low, the system achieves effective blocker signal removal during the initial phase while allowing faster settling compared to a permanently high cutoff frequency configuration.
2Productivity
If the settling time is reduced for faster chirp repetitions, then fast-moving target detection is enabled, but the blocker signal removal becomes insufficient
Solution Approach 1:
The patent applies periodic action by using different filter configurations during different time periods of the chirp signal. During the initial portion, a higher cutoff frequency provides strong blocker rejection, while during the latter portion, a lower cutoff frequency maintains signal integrity, enabling faster chirp repetitions without sacrificing blocker removal effectiveness.
3Object-affected harmful factors
If a fixed high-pass filter is used, then the blocker signal is consistently filtered, but the radar frequency bandwidth is wasted during settling
Solution Approach 1:
The patent makes the filter characteristics dynamic rather than fixed. By adjusting the cutoff frequency from high to low during the chirp signal, the system achieves effective blocker removal only when necessary during the initial settling phase, thereby conserving radar frequency bandwidth during the productive sampling period.
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 reduces the settling time of the ADC output, enabling faster chirp repetition and improved detection of fast-moving targets while conserving radar frequency bandwidth.
Implementation Method 1
the high-pass filter can slow the settling of the intermediate frequency signal after turn-on
Data Source
AI summary
A device comprises a digital ramp generator, an oscillator, a power amplifier, a low-noise amplifier (LNA), a mixer, and an intermediate frequency amplifier (IFA). The oscillator generates a chirp signal based on an output from the digital ramp generator. The power amplifier receives the chirp signal and outputs an amplified chirp signal to a transmitter antenna. The LNA receives a reflected chirp signal from a receiver antenna. The mixer receives output of the LNA and combines it with the chirp signal from the oscillator. The IFA receives the mixer output signal and includes a configurable high-pass filter, which has a first cutoff frequency during a first portion of the chirp signal and a second cutoff frequency during a second portion of the chirp signal. In some implementations, the first cutoff frequency is chosen based on a frequency of a blocker signal introduced by couplings between the transmitter and receiver antennas.