Sampling ADC Calibration Tone Injection for Pulsed Signal Capture

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

RF sampling ADCs operating at high sampling rates require periodic gain and time skew calibration, which is challenging for systems processing low duty cycle or pulsed waveforms, as they cannot be taken offline for calibration without affecting signal capture reliability.

Innovation Solution

A calibration system that generates a continuous or near-continuous calibration signal, embedded in a specific frequency band, to enable self-calibration of ADCs without interfering with received signals, using a calibration tone and signal summing circuit to ensure synchronization of sub-converters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If periodic calibration is performed by taking the ADC offline, then calibration accuracy is improved, but signal capture reliability deteriorates

Engineering Contradiction:

Improvecalibration accuracyVSAvoidsignal capture reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The calibration signal is injected into the ADC input before the actual signal processing begins, allowing calibration to occur in advance without interrupting signal capture operations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A calibration signal generator and summing circuit are introduced as intermediary components to combine the calibration signal with the received signal, enabling calibration without taking the ADC offline

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If a calibration signal is injected into the ADC input, then calibration capability is improved, but interference with received signals worsens

Engineering Contradiction:

Improvecalibration capabilityVSAvoidsignal interference

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The calibration signal is confined to a specific frequency band distinct from the received signal band, allowing calibration operations without interfering with the actual signal processing in other frequency ranges

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system dynamically adjusts the frequency band and amplitude of the calibration signal based on the characteristics of the received signal, ensuring calibration effectiveness while minimizing interference

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11476876B1Calibration signal generation for a sampling analog to digital converter

Publication Date: 2022.10.18 BAE SYSTEMS INFORMATION ANDELECTRONIC SYSTEMS INTEGRATION INC

AI summary

Techniques are provided for the generation of a calibration signal for use on an analog to digital converter (ADC). A system implementing the techniques according to an embodiment includes a calibration signal generator configured to generate a calibration tone, located in a first frequency band, in response to a calibration enable signal. The system also includes a signal summing circuit configured to generate an ADC input signal as a sum of a received signal and the calibration tone. The received signal is located in a second frequency band. The system further includes an ADC circuit configured to convert the ADC input signal to a baseband digital output signal and to perform self-calibration, based on the calibration tone, in response to the calibration enable signal. The frequency bands and the amplitude of the calibration tone are chosen to reduce interference between the received signal and the calibration tone.