Averaging Mixer Front-End With Integrated Gain for Low-Noise RF Reception
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Solution Overview
Problem
Existing RF receiver front-ends face challenges with high noise, power consumption, and linearity issues, particularly in low power applications where additional amplification is not feasible, and they require significant silicon area and power dissipation.
Innovation Solution
An electric circuit for a RF receiver front-end that integrates an I path and Q path with switches, input capacitors, operational amplifiers, and a bias resistor, utilizing an averaging mixer to provide simultaneous mixing and gaining functions, reducing the need for additional amplification and minimizing noise and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive mixers are used, then noise performance and linearity are improved, but power gain is lost requiring additional amplification
Solution Approach 1:
The patent merges the mixing function and amplification function into a single integrated circuit block. The operational amplifier simultaneously performs signal mixing (through the feedback network with switches and capacitors) and signal amplification, eliminating the need for separate passive mixer and amplifier stages. This integration resolves the contradiction by providing both low noise performance (inherent to passive mixing) and power gain (provided by the operational amplifier) in one unit.
2Power
If active mixers are used, then power gain is provided, but linearity deteriorates and noise increases
Solution Approach 1:
The patent segments the active mixer circuit into distinct functional components: switching elements (providing mixing action), capacitive elements (providing signal path), and an operational amplifier (providing controlled gain). The switching elements operate in a linear fashion during their on-state, and the operational amplifier provides controlled amplification with high linearity, avoiding the non-linear distortion issues of traditional active mixers while maintaining power gain.
3Power
If additional amplification stages are added, then power gain is increased, but silicon area and power consumption increase
Solution Approach 1:
The patent combines multiple functions (mixing, amplification, filtering) into a single integrated operational amplifier circuit with associated passive components. This eliminates the need for separate amplifier stages that would require additional silicon area and power consumption, while still achieving the required power gain through the integrated amplifier's feedback network.
4Power
If additional amplification stages are added, then power gain is increased, but noise and power consumption increase
Solution Approach 1:
The patent integrates amplification and mixing functions in a single operational amplifier stage with feedback network, eliminating the need for multiple amplifier stages. This reduces total power consumption while maintaining the required power gain, as the integrated design allows for optimized biasing and signal paths that minimize energy loss compared to cascaded amplifier stages.
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 achieves low noise, good linearity, and reduced power consumption while minimizing silicon area, making it suitable for low power applications and simplifying filtering in the analog baseband circuitry.
Implementation Method 1
the operational amplifier, a feedback capacitor having a first terminal connected to the input of the operational amplifier and a second terminal connected to the output of the operational amplifier
Implementation Method 2
a gate of the switch being coupled to the LO, a command module arranged to sequentially close each switch during a mixer's averaging window
Implementation Method 3
a feedback capacitor having a first terminal connected to the input of the operational amplifier and a second terminal connected to the output of the operational amplifier
Implementation Method 4
a bias resistor so as to DC-bias the operational amplifier input
Data Source
Figure 1
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Figure 3
AI summary
An electric circuit providing mixing and gaining functions (20) for a RF receiver front-end (1), comprising an I path and a Q path, wherein each of the I path and the Q path comprises: - a switch (SWIP, SWQP), - an input capacitor (C1) between the switch (SWIP, SWQP) and an input of an operational amplifier (OA1, OA2), - the operational amplifier (OA1, OA2), - a feedback capacitor (C2) between the input and the output of the operational amplifier (OA1, OA2), the electric circuit (20) comprising: - a local oscillator arranged to generate a carrier signal having a carrier frequency, - a command module arranged to sequentially close each switch (SWIP, SWQP) during a mixer's averaging window, so that an incoming signal having a frequency close to the carrier frequency results in a non-zero down-converted signal across the input capacitor (Ci), this down-converted signal being then amplified by the operational amplifier (OA1, OA2) so that an amplified down-converted signal appears at the output of the operational amplifier (OA1, OA2). The present invention also concerns a RF front-end (1) which in embodiments is inductor-less, comprises a linearity optimized LNA, allows to tradeoff power dissipation for sensitivity and/or has reconfigurable topology saving power at the expense of the C/I and/or alias attenuation.