Active Quadrature Circuit Using BJT Phase Difference
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Solution Overview
Problem
Quadrature generation circuits face accuracy issues due to variations in passive element resistors and high power consumption in active element circuits, necessitating a solution that balances accuracy with reduced power usage.
Innovation Solution
An active quadrature generation circuit utilizing two differently sized bipolar junction transistors (BJTs) with a scaling factor K, where the in-phase and quadrature output signals are generated based on a 90-degree phase difference between the current at the collector and base of the transistors, achieving phase and amplitude balance with reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If passive RC circuits are used for quadrature generation, then power consumption is reduced, but accuracy deteriorates due to resistor value variations
Solution Approach 1:
The patent replaces passive RC circuits with an active quadrature generation circuit using bipolar junction transistors. The active circuit generates quadrature signals by exploiting the inherent 90-degree phase difference between collector and base currents, eliminating dependence on passive resistor values and their associated accuracy issues while maintaining lower power consumption through efficient transistor operation.
Solution Approach 2:
The patent changes the operating parameters by using transistor current relationships instead of RC time constants. By sizing the transistors with a specific factor K and utilizing the phase difference between collector and base currents, the circuit achieves accurate quadrature generation without being sensitive to component value variations, thus improving accuracy while controlling power consumption.
2Measurement precision
If active elements are used for quadrature generation, then accuracy is improved, but power consumption increases
Solution Approach 1:
The patent employs bipolar junction transistors configured to exploit their inherent current-phase relationships. The active circuit uses the natural 90-degree phase difference between collector and base currents, achieving high accuracy through active element characteristics while optimizing power consumption through efficient transistor biasing and operation modes.
Solution Approach 2:
The patent optimizes the operating parameters of the active transistors by sizing them with factor K and operating them in a mode that leverages the phase difference between collector and base currents. This parameter optimization enables the active circuit to achieve high accuracy while consuming less power than conventional active quadrature generation circuits.
3Ease of manufacture
If resistor values are varied due to manufacturing process, then device complexity is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The patent replaces the passive RC approach with an active transistor-based circuit that is inherently less sensitive to manufacturing variations. By using transistor current relationships and sizing factors rather than precise resistor values, the circuit maintains ease of manufacture while significantly improving manufacturing precision and accuracy.
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
The solution provides accurate quadrature signals with minimal power consumption, ensuring a 90-degree phase difference and amplitude balance at high frequencies, while being immune to common-mode interferences and temperature variations.
Implementation Method 1
an inherent phase difference of 90 degrees between a current at a collector of the first transistor and a current at a base of the second transistor
Data Source
AI summary
An active quadrature generation circuit configured to provide an in-phase output signal and a quadrature output signal based on an input signal and a method of fabricating the active quadrature generation circuit on an integrated circuit are described. The circuit includes an input node to receive the input signal and a first transistor including a collector connected to a power supply pin. The circuit also includes a second transistor including a base connected to the power supply pin, the second transistor differing in size from the first transistor by a factor of K, wherein the in-phase output signal and the quadrature output signal are generated based on an inherent phase difference of 90 degrees between a current at a collector of the first transistor and a current at a base of the second transistor.