Conversion Mixer High-Impedance Isolation for Linear Output Range
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Solution Overview
Problem
Conventional conversion mixers, such as Gilbert-cell mixers, face issues with high power consumption and non-linear output signals with limited operational range due to the influence of the loading circuit on the baseband current signals, leading to a dead zone phenomenon.
Innovation Solution
A conversion mixer design incorporating a mixing circuit, a duplicating circuit, and a loading circuit, where the duplicating circuit separates the mixing circuit from the loading circuit, and optionally utilizing a high impedance circuit to shunt DC and AC components, allowing only AC components of the mixed signals to be duplicated, thereby reducing the loading circuit's influence and achieving linear output signals with a larger operational range while minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a larger current is provided to drive the Gilbert-cell mixer, then the mixing function is improved, but the power consumption increases and the voltage residual becomes too low
Solution Approach 1:
The patent divides the loading circuit into two separate loading circuits, each connected to one of the differential output terminals. This segmentation allows the mixed signals to be loaded and converted to voltage form without requiring excessive current from a single loading circuit, thereby reducing power consumption while maintaining mixing capability.
Solution Approach 2:
The patent introduces a voltage source as an intermediary element connected between the two loading circuits. This voltage source serves as a mediator that provides the necessary voltage potential for the differential signaling while allowing the loading circuits to operate with reduced current draw, thus resolving the contradiction between mixing capability and power consumption.
2Device complexity
If the loading circuit directly loads the mixed signals, then the signal conversion is simplified, but the baseband current signals are influenced by the loading circuit causing non-linear outputs and dead zone phenomenon
Solution Approach 1:
The patent segments the loading function into two separate loading circuits that operate differentially. This segmentation isolates each mixed signal from the direct influence of a single loading circuit, reducing the loading effect on individual baseband current signals and thereby improving signal linearity while avoiding dead zone phenomenon.
Solution Approach 2:
The patent changes the operating parameters by using differential signaling and introducing a voltage source to establish a virtual ground. This parameter change transforms the single-ended loading operation into differential loading, which balances the influence of the loading circuit and improves the linearity of the baseband current signals.
3Power
If the residual voltage of the supply power is too low, then the voltage headroom is reduced, but the operation regions of the transistors are influenced causing dead zone phenomenon
Solution Approach 1:
The patent introduces a voltage source as an intermediary that provides a stable reference potential between the two loading circuits. This voltage source acts as a mediator that maintains adequate voltage headroom for transistor operation even when the overall supply voltage is reduced, preventing the transistors from entering the dead zone region.
Solution Approach 2:
The patent creates a virtual ground through the voltage source that establishes an equipotential reference point for the differential signaling. This equipotential reference allows the transistors to operate in their linear regions with reduced voltage headroom, as the differential operation maintains the necessary voltage swings without requiring excessive supply voltage.
Data Source
AI summary
A conversion mixer includes a mixing circuit, a duplicating circuit and a loading circuit. The mixing circuit receives a couple of first input signals and a couple of second input signals and mixes the couple of first input signals with the couple of second input signals to output a couple of mixed signals. The duplicating circuit coupled to the mixing circuit receives the couple of mixed signals and duplicates the couple of mixed signals to output a couple of duplicated signals. The loading circuit coupled to the duplicating circuit receives the couple of duplicated signals and outputs a couple of output signals according to the couple of duplicated signals.