Capacitive-Coupled MOS Mixer Circuit for Low-Voltage Operation
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Solution Overview
Problem
Mixer circuits for radio communications face challenges in operating at low voltage and low power due to the need for multiple stages of MOS transistors, which consume power through DC bias currents, making them unsuitable for portable equipment.
Innovation Solution
A mixer circuit configuration using capacitive coupling and MOS transistors with impedance elements to add and square analog signals, eliminating the need for a separate adding circuit and reducing power consumption by utilizing square-law characteristics of MOS transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If mixer circuits are made up of MOS transistors stacked in two stages or more, then frequency conversion function is achieved, but power consumption increases due to DC bias currents
Solution Approach 1:
The patent combines the adding circuit and mixer circuit into a single integrated structure. The adding circuit uses capacitive coupling to combine input signals, while the mixer circuit uses MOS transistors to perform frequency conversion. This merging eliminates the need for separate adding and mixer circuits, reducing overall power consumption and device complexity.
Solution Approach 2:
The patent designs the circuit to perform multiple functions within a single structure. The same MOS transistors and capacitive coupling elements are used for both signal addition and frequency conversion operations. This multi-functionality reduces the number of separate components needed, thereby reducing power consumption and simplifying the overall circuit design.
2Power
If a separate adding circuit is used to add analog signals, then signal addition function is achieved, but power consumption increases due to DC bias currents of MOS transistors
Solution Approach 1:
The patent merges the adding circuit and mixer circuit into one integrated structure. The adding circuit uses capacitive coupling to combine input signals, and the mixer circuit uses MOS transistors for frequency conversion. This integration eliminates the need for separate adding and mixer circuits, reducing power consumption and device complexity.
Solution Approach 2:
The patent introduces capacitive coupling as an intermediary mechanism to add analog signals without requiring DC bias currents. The capacitors couple the input signals together in the time domain, enabling signal addition while avoiding the power consumption associated with traditional MOS transistor-based adding circuits.
3Device complexity
If technology scaling arises with CMOS process development, then integration density is improved, but power supply voltage reduction becomes a serious problem
Solution Approach 1:
The patent employs capacitive coupling to perform signal addition in the time domain, which is a periodic action that does not require continuous DC bias currents. This approach allows the circuit to operate at lower power supply voltages while maintaining integration density benefits from CMOS technology scaling.
Solution Approach 2:
The patent changes the operating parameters of the circuit by using capacitive coupling instead of DC bias currents for signal addition. This parameter change enables the circuit to function effectively at reduced power supply voltages, accommodating the voltage reduction trends associated with CMOS process scaling.
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
Enables low-voltage and low-power operation by eliminating the need for a separate adding circuit, reducing power consumption, and achieving efficient signal multiplication and addition without DC bias current consumption.
Implementation Method 1
A mixer circuit configuration using capacitive coupling and MOS transistors with impedance elements to add and square analog signals
Implementation Method 2
reducing power consumption by utilizing square-law characteristics of MOS transistors
Data Source
AI summary
In a mixer circuit, addition of analog signals by capacitive coupling is used and square-law characteristics of the drain current of a MOS transistor operating in a saturated region are used. With this configuration, the voltage and power of the mixer circuit can be reduced.