Local Oscillator Mixer Topology for Low-Loss Frequency Selection
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Solution Overview
Problem
Conventional local oscillation generators in wireless communication devices suffer from signal loss and increased power consumption due to parasitic capacitance and resistance in switches used for frequency division, particularly in mobile devices like cell phones.
Innovation Solution
The design incorporates a local oscillation generator with a mixer that selects a divider output signal by enabling a power path in a transconductance stage, avoiding signal loss by bypassing switches in the signal path and reducing power consumption by using lower frequency dividers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If switches are used to selectively route the primary frequency signal through frequency dividers, then different divided frequency signals can be generated, but parasitic capacitor and resistance in the switches cause signal loss and increased power consumption
Solution Approach 1:
The patent extracts the switching function from the signal path and relocates it to the power path. The mixer core is designed without switches in the signal path, eliminating parasitic effects. Frequency selection is achieved by enabling/disabling power supply to different transconductance stages through switches in the power path, separating the switching function from signal transmission.
Solution Approach 2:
The patent introduces power supply control as an intermediary mechanism. Instead of using switches to directly route signals, the invention uses power supply switches to control the activation of transconductance stages. This intermediary approach allows frequency selection without placing switches in the critical signal path, thereby avoiding signal loss.
2Adaptability or versatility
If switches are used for frequency division routing, then multiple output frequencies can be achieved, but the parasitic resistance increases power consumption
Solution Approach 1:
The switching function is extracted from the signal path and placed in the power path. This eliminates parasitic resistance in the signal path while maintaining frequency selection capability through power-controlled transconductance stage activation.
Solution Approach 2:
The patent changes the control parameter from signal path switching to power path switching. By controlling the power supply state of different transconductance stages, the system achieves frequency selection without the power consumption penalties associated with switch resistance in the signal path.
Data Source
AI summary
According to one exemplary embodiment, a local oscillation generator includes a mixing stage for receiving a primary frequency and one of a number of related frequencies. The local oscillation generator further includes a first transconductance stage to provide a first related frequency to the mixing stage when a first switch selectably enables a first power path in the first transconductance stage. The local oscillation generator further includes a second transconductance stage to provide a second related frequency to the mixing stage when a second switch selectably enables a second power path in the second transconductance stage. The local oscillation generator further includes a number of dividers, where an output of a first divider provides the first related frequency to an input of the first transconductance stage, and where an output of a second divider provides the second related frequency to an input of the second transconductance stage.