DC Bias Loop Mixer With Replica Path for Excess Current Absorption
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Solution Overview
Problem
Mixer circuits in telecommunication modules experience increased current consumption due to input RF power, leading to higher power consumption and noise in the signal chain, which existing solutions address with common mode current sourcing and source degeneration, but these methods require additional headroom and reduce gain.
Innovation Solution
A mixer circuit that absorbs excess current in the mixer branch, preventing its propagation and reducing overall power consumption by using a replica path to mirror power to load devices, thereby eliminating the need for common mode current sourcing and source degeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If common mode current sourcing and source degeneration are used to control mixer current, then power consumption is reduced, but additional headroom is required and gain is reduced
Solution Approach 1:
A replica mixer circuit is introduced as an intermediary to sense and control the current in the main mixer. The replica path includes replica transistors that mirror the main mixer's current consumption, allowing indirect control through a dedicated control node that adjusts the local oscillator signal amplitude to maintain constant current in the replica, thereby controlling the main mixer's current without direct intervention in its signal path.
Solution Approach 2:
The patent implements a feedback mechanism where the control node monitors the current in the replica mixer and adjusts the local oscillator signal accordingly. The replica mixer's current consumption serves as a feedback signal that reflects the main mixer's current state, enabling automatic regulation to maintain constant current and reduce power consumption while preserving headroom and gain.
2Use of energy by moving object
If common mode current sourcing and source degeneration are used to control mixer current, then power consumption is reduced, but gain is reduced
Solution Approach 1:
The replica mixer acts as an intermediary that indirectly controls the main mixer's current without interfering with its signal path. By adjusting the local oscillator signal amplitude through the control node based on replica current feedback, the system reduces power consumption while preserving the main mixer's gain characteristics, as the control is applied to the current path rather than the signal path.
3Productivity
If mixer current increases with input RF power, then signal processing capability is maintained, but overall power consumption increases
Solution Approach 1:
The feedback mechanism continuously monitors the replica mixer's current consumption, which mirrors the main mixer's current that varies with input RF power. The control node automatically adjusts the local oscillator signal amplitude to compensate for RF power variations, maintaining constant current and power consumption regardless of the input signal strength, thereby decoupling productivity from power consumption.
Solution Approach 2:
The system uses its own current consumption characteristics (through the replica mixer) to automatically regulate itself. The replica mixer serves itself by providing a real-time indicator of the main mixer's current state, enabling the control node to self-adjust the local oscillator signal and maintain constant power consumption without external intervention.
Data Source
AI summary
A current mixer is including a mixing section including a first impedance, a second impedance, a first transistor coupled to the first impedance, a second transistor coupled to the second impedance, a third transistor coupled to the first impedance, a fourth transistor coupled to the second impedance, a fifth transistor coupled to the first and second impedance, a sixth transistor coupled to the third and fourth impedance, a seventh transistor coupled to the first impedance and to the first transistor, and an eighth transistor coupled to the second impedance and fourth transistor; and a replica path including a first replica transistor, a second replica transistor coupled to the first replica transistor, and a third replica transistor coupled to the first replica transistor.