Mixer-First RF Receiver With Direct Bottom-Plate Baseband Readout
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Solution Overview
Problem
Mixer-first receivers with bottom-plate mixing techniques face challenges in achieving high linearity without additional V-I conversion, which introduces gain loss and noise due to the floating capacitor issue during baseband signal read-out.
Innovation Solution
The proposed radio frequency receiver utilizes a mixer circuitry with switched capacitors connected through switches to a signal line, allowing direct sensing of baseband signal components at the switch side nodes, eliminating the need for V-I conversion by leveraging circuital symmetry and phase-shifted clock phases for enhanced voltage gain and harmonic rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If bottom-plate mixing technique is used to achieve high linearity, then linearity is improved, but the capacitor becomes floating during readout requiring additional V-I conversion which introduces gain loss and noise
Solution Approach 1:
The patent inverts the conventional bottom-plate mixing approach by switching the top plate to ground instead of the bottom plate. This inversion allows the baseband signal to be directly available at the bottom plate node without requiring V-I conversion, thereby maintaining the linearity benefits of bottom-plate mixing while eliminating the floating capacitor readout problem.
Solution Approach 2:
The patent extracts the baseband signal directly from the bottom plate node by switching the top plate to ground, separating the signal extraction function from the mixing function. This allows direct voltage readout without requiring additional V-I conversion circuitry, reducing complexity and noise while maintaining linearity.
2Ease of operation
If V-I conversion is used to read out baseband signal from floating capacitor, then signal readout is enabled, but gain loss and additional noise are introduced
Solution Approach 1:
By inverting which plate is switched to ground, the patent enables direct voltage readout of the baseband signal from the bottom plate without requiring V-I conversion. This maintains signal quality while enabling readout capability.
Solution Approach 2:
The patent uses the ground switch as an intermediary mechanism to enable direct voltage readout. By switching the top plate to ground, the bottom plate voltage becomes directly accessible without requiring resistive V-I conversion, thus avoiding the associated gain loss and noise.
3Ease of operation
If top-plate mixing is used, then baseband signal is stored on grounded capacitor for easy readout, but channel resistance modulation significantly limits linearity
Solution Approach 1:
The patent inverts the top-plate mixing configuration by switching the top plate to ground instead of the bottom plate. This inversion preserves the linearity advantages of bottom-plate mixing (avoiding channel resistance modulation) while still enabling direct voltage readout of the baseband signal from the bottom plate node.
Data Source
AI summary
A radio frequency receiver comprising mixer circuitry to down-convert a received signal, which is transported on a signal line to baseband signal components, is provided. The mixer circuitry comprises a plurality of switched capacitors, each connected to the signal line through a signal side node and to a corresponding switch through a switch side node. In this context, a voltage is sensed at each switch side node of the plurality of switched capacitors and is read out through a respective grounded capacitor.