Mixer LO Filtering With Half-Wavelength Line for Low-Noise Linearity
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Solution Overview
Problem
Existing RF receiver frontends face challenges in balancing noise performance and linearity, with mixer-first configurations degrading noise performance and increasing power consumption, while double-balanced mixers generate more noise and consume more power.
Innovation Solution
An integrated circuit with a mixer that includes a filter circuit, such as a half-wavelength transmission line, to selectively filter out common-mode signals above a threshold frequency and differential signals below, reducing LO amplifier-generated noise and improving noise figure while maintaining high linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a mixer-first configuration is used, then linearity is improved, but noise performance degrades and power consumption increases
Solution Approach 1:
The patent extracts and removes the harmful LO amplifier-generated noise from the mixer input by introducing a filter circuit that selectively filters out common-mode signals above a threshold frequency, thereby improving noise performance while maintaining the mixer-first configuration's linearity advantages
Solution Approach 2:
The filter circuit acts as an intermediary component between the LO amplifier and the mixer, mediating the signal flow by blocking harmful noise frequencies while allowing desired signals to pass through, thus resolving the noise performance degradation issue
2Object-affected harmful factors
If a double-balanced mixer topology is used, then LO signal cancellation is improved, but device size increases and power consumption increases
Solution Approach 1:
The patent applies local quality by implementing filtering only at the specific location where LO noise is injected into the mixer (the LO input port), rather than using a full double-balanced topology throughout the entire circuit, thus achieving noise cancellation with reduced device size
Solution Approach 2:
The patent segments the LO signal path by introducing a separate filter circuit that handles only the noise filtering function, separating it from the main mixing function, allowing each component to be optimized independently for size and performance
3Object-affected harmful factors
If a double-balanced mixer topology is used, then LO signal cancellation is improved, but power consumption increases
Solution Approach 1:
The patent extracts the noise filtering function from the main mixer circuit and implements it through a separate, energy-efficient filter circuit that consumes significantly less power than a full double-balanced topology while achieving the same LO signal cancellation benefit
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 solution reduces the size and power consumption of the RF receiver, enabling improved noise figure and linearity, facilitating the use of MIMO radar systems with reduced area and power consumption.
Implementation Method 1
a filter circuit, electrically coupled in parallel with the input ports, that filters out common-mode signals above a threshold frequency and filters out differential signals below the threshold frequency
Implementation Method 2
the filter circuit may include a transmission line. For example, the transmission line may include a half-wavelength transmission line
Data Source
AI summary
An integrated circuit that selectively filters out common-mode and differential signals is described. This integrated circuit may include an RF receiver with a mixer that converts signals between a band of frequencies in the RF and a second band of frequencies based at least in part on second signals, where the second band of frequencies is less than the band of frequencies. Moreover, the mixer may include input ports that receive the second signals and include a filter circuit, electrically coupled in parallel with the input ports, that filters out the common-mode signals above a threshold frequency and filters out the differential signals below the threshold frequency. For example, the filter circuit may include a half-wavelength transmission line. Note that the mixer may convert the differential signals to the common-mode signals below the threshold frequency and may convert the common-mode signals to the differential signals above the threshold frequency.