Mixer-First Receiver Impedance Tuning for Low Power
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Solution Overview
Problem
Conventional wireless communication receivers face challenges in achieving low-cost designs with flat in-band response and sharp adjacent-band rejection due to high power consumption and non-linearity issues with low-noise amplifiers, and the use of large capacitors which reduce gain and occupy significant chip area.
Innovation Solution
A mixer-first signal receiver design incorporating a first and second amplifying device, a feedback device, and a passive mixing device, where the second amplifying device adjusts its input impedance across different frequency ranges to maintain a flat in-band response and sharp adjacent-band rejection, reducing the need for large capacitors and minimizing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low-noise amplifier is used to amplify the wireless signal, then the signal quality is improved, but the power consumption increases and non-linearity distortion occurs
Solution Approach 1:
The patent extracts the low-noise amplifier from the receiver chain and replaces it with a passive mixer as the first active component. This removal of the LNA eliminates its high power consumption and non-linearity issues while the passive mixer provides the necessary signal processing function without amplifying the input signal
Solution Approach 2:
The patent uses a passive mixer instead of an expensive and power-hungry LNA. The passive mixer is a simpler, lower-cost component that achieves the required functionality without the drawbacks of active amplification at the input stage
2Reliability
If a large capacitor is used to provide sharp filtering effect, then the adjacent-band rejection is improved, but the gain in required in-band frequency is reduced and chip area increases
Solution Approach 1:
The patent employs a second amplifying device with dynamically adjustable input impedance that changes with frequency. This dynamic impedance adjustment creates frequency-selective gain without requiring large capacitors, achieving sharp adjacent-band rejection while maintaining flat in-band response and avoiding gain reduction
Solution Approach 2:
The patent changes the impedance parameter of the second amplifying device based on frequency. By adjusting the input impedance to fall within different impedance ranges for different frequency ranges, the system achieves frequency-dependent filtering and gain characteristics without using large capacitive elements
3Reliability
If a large capacitor is used to provide sharp filtering effect, then the adjacent-band rejection is improved, but the chip area occupied increases
Solution Approach 1:
The patent replaces static large capacitors with a dynamically adjustable amplifying device whose input impedance changes with frequency. This dynamic approach achieves the same filtering effect as large capacitors but with much smaller chip area, as the impedance control is achieved through active circuit elements rather than large passive components
Solution Approach 2:
The patent uses parameter changes in the amplifying device's operating characteristics to achieve frequency-selective filtering. By controlling the input impedance parameter across different frequency ranges, the system replaces the need for large physical capacitors with a compact active circuit implementation
Data Source
AI summary
A signal receiving apparatus includes: a first amplifying device, a second amplifying device, a feedback device, and a mixing device, wherein the mixing device is a passive mixer, the second amplifying device is arranged to provide an input impedance looking into an input terminal of the second amplifying device to fall within a first impedance range when the second amplifying device operates in a first frequency range, the second amplifying device is arranged to provide the input impedance looking into the input terminal of the second amplifying device to fall within a second impedance range when the second amplifying device operates in a second frequency range, the second frequency range is different from the first frequency range, and the second impedance range is different from the first impedance range.