Ground LDO Regulator Attenuates DAC Spurs
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Solution Overview
Problem
In wireless communication devices, the integration of sensitive analog/RF blocks with noisy digital processing circuits leads to switching noise propagation through the power and ground distribution network, causing degraded performance and DAC spur issues that desensitize the receive path.
Innovation Solution
The implementation of a ground low drop-out regulator (GND LDO) that injects a reference voltage, measures its output, and adjusts the amplifier output based on comparison to attenuate DAC spurs, providing a clean ground to the DAC core and reducing noise-induced spur interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If sensitive analog/RF blocks are integrated with noisy digital processing circuits on the same die, then device size is reduced and functionality is increased, but switching noise propagates through the power and ground distribution network causing degraded performance and DAC spur issues
Solution Approach 1:
The patent segments the ground distribution network by introducing a dedicated clean ground path for the DAC core through the GND LDO circuitry, separating it from the noisy digital ground to prevent noise propagation while maintaining integration
Solution Approach 2:
The GND LDO acts as an intermediary element between the noisy digital ground and the sensitive DAC core, providing a cleaned ground reference that filters out switching noise while maintaining the integrated architecture
2Adaptability or versatility
If multiple transistors and functions are implemented in the same die, then device capability is increased, but switching noise increases and performance degrades
Solution Approach 1:
The patent applies local quality improvement by providing a localized clean ground reference specifically at the DAC core through the GND LDO, addressing the noise issue locally without requiring separate physical packages for analog and digital circuits
3Device complexity
If the number of power and ground pins is limited, then package complexity is reduced, but noise coupling is facilitated
Solution Approach 1:
The GND LDO serves as an intermediary that cleans the ground reference internally within the device, compensating for the limited number of ground pins by providing noise isolation through the regulated ground path rather than requiring multiple separate ground connections
4Reliability
If a GND LDO is used to attenuate DAC spurs, then receive band performance is improved, but device complexity increases
Solution Approach 1:
The GND LDO is designed to be self-contained with integrated transistors and control logic that automatically regulates the ground reference without requiring external intervention, providing spur attenuation while minimizing the increase in overall device complexity
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 solution effectively attenuates DAC spurs by up to 13 dB, improving receive band performance without degrading other bands, thus enhancing the overall quality of wireless communication.
Implementation Method 1
The output of the ground low drop-out regulator may be measured and may then be compared with the reference voltage
Implementation Method 2
The output of the amplifier may then be adjusted based on the results of the comparison
Data Source
AI summary
A method and apparatus for attenuating transmit digital to analog converter (DAC) spurs is provided. The method begins when a reference voltage is injected into an amplifier. Next, an output of the ground low drop-out regulator is measured and is them compared with the reference voltage. The output of the amplifier is then adjusted based on the results of the comparison. If the reference voltage is higher then the output of the ground low drop-out regulator the output of the amplifier is adjusted to ground. If the reference voltage is lower than the output of the ground low drop-out regulator then the output of the amplifier is adjusted to match the reference voltage.