Series Mixer Phase Detection for High Sensitivity Low-Noise PLLs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing phase detectors in PLL systems face limitations in achieving high sensitivity with low noise levels, as conventional mixers and digital phase detectors either saturate or produce high intrinsic noise.
Innovation Solution
A phase detection apparatus comprising multiple mixer units connected in series, where the ground potential of each unit is connected to the output of the previous unit, and a varying reference potential is used, allowing for increased voltage swing and reduced noise through a series connection and low-pass filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional mixers are used in phase detectors, then the device can be manufactured with standardized components, but the sensitivity is limited due to saturation of the device
Solution Approach 1:
The invention divides the phase detector into multiple mixer units connected in series. Each mixer unit processes the phase detection independently, and their outputs are combined. This segmentation allows the system to achieve higher sensitivity than a single mixer while still using standardized components, as each unit operates within its linear range without saturation.
2Measurement precision
If digital phase detectors are used, then higher sensitivity can be achieved compared to double-balanced mixers, but high intrinsic noise levels are introduced
Solution Approach 1:
The invention replaces digital logic gate arrangements with analog mixer units that use passive non-linear devices. This substitution eliminates the high intrinsic noise generated by digital switches and logic gates while maintaining high sensitivity through the series connection of multiple mixer units, achieving low noise levels below -180 dBc/Hz.
3Object-generated harmful factors
If double-balanced mixers are used, then low noise floor levels of about -180 dBc/Hz can be achieved, but the sensitivity is limited due to saturation
Solution Approach 1:
The invention merges multiple mixer units in series connection, where the output of one mixer feeds into the next. This combination allows the system to accumulate the sensitivity benefits of multiple units while maintaining the low noise floor characteristics of double-balanced mixers, as each unit contributes to the overall phase detection without introducing significant additional noise.
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 apparatus achieves significantly higher sensitivity and lower noise levels compared to conventional detectors, enabling the realization of very low noise PLL systems.
Implementation Method 1
A mixer is a passive non-linear device that produces multiple output frequencies based on two input signals. The IF signal comprises the sums and differences of integer multiples of the input frequencies.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Disclosed is an apparatus (100) for high sensitivity phase detection of an electric signal by means of a local oscillator. The apparatus (100) comprises a first mixer unit (110) with a first electric signal connector (111), a first local oscillator connector (112), a first output connector (113), and a first reference connector (114), and the apparatus (100) comprises a second mixer unit (120) with a second electric signal connector (121), a second local oscillator connector (122), a second output connector (123), and a second reference connector (124). The first mixer unit (110) and the second mixer unit (120) are each configured to mix the electric signal with the local oscillator and based thereon produce an output with respect to a potential at the first reference connector (114) or second reference connector (124), respectively. The apparatus comprises a link (140) between the first output connector (113) and the second reference connector (124). The link (140) is configured to provide an input to the second reference connector (124) which is based on an output of the first output connector (113).