Switchable Degeneration Impedance Circuit for Multi-Band Oscillators
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Solution Overview
Problem
Existing electronic circuits, such as voltage controlled oscillators and frequency dividers, face challenges in managing noise insertion due to fixed degeneration impedance, which limits their applicability to multi-band frequency signals, as varactors can only tune frequencies within a predetermined band.
Innovation Solution
A variable degeneration impedance supply circuit is developed using alternately connected transistors, a capacitor circuit, and switches to control the degeneration impedance, allowing for precise adjustment through control signals, enabling operation in multi-band coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed degeneration impedance is used, then the circuit structure is simple, but the circuit cannot operate in multi-band frequency coverage
Solution Approach 1:
The patent applies dynamics by making the degeneration impedance adjustable through switching elements. The impedance can be dynamically changed between different states (degeneration and non-degeneration modes) to adapt to different frequency bands, resolving the contradiction between fixed simplicity and multi-band adaptability.
Solution Approach 2:
The patent implements universality by designing a circuit that can function in multiple modes: it can operate as a degeneration impedance circuit for noise filtering or as a non-degeneration circuit for other frequency bands. The switching mechanism enables one circuit structure to serve multiple frequency band requirements.
2Adaptability or versatility
If a varactor is used for frequency tuning, then the oscillating frequency can be adjusted within a band, but the circuit cannot operate in multi-band coverage
Solution Approach 1:
The patent applies segmentation by dividing the frequency tuning range into multiple discrete bands. Instead of continuous tuning within a single band using a varactor, the circuit uses switching elements to select between discrete impedance states, enabling precise operation at specific frequency bands while maintaining the ability to cover multiple bands.
3Object-affected harmful factors
If degeneration impedance is applied to remove noise, then the noise filtering performance is improved, but the circuit performance in other frequency bands is limited
Solution Approach 1:
The patent applies periodic action through time-sequential switching between degeneration and non-degeneration modes. The circuit can apply noise filtering (degeneration) during specific time periods when operating in certain frequency bands, and switch to non-degeneration mode during other periods for different frequency bands, achieving both noise filtering and multi-band performance.
Data Source
AI summary
A variable degeneration impedance supply circuit, including: two alternatively connected transistors; a capacitor circuit having a predetermined capacitance and serially connecting output terminals of the two transistors; and a switch for controlling on/off state between the capacitor circuit and the output terminal, according to a predetermined first control signal. The circuit further includes: at least one sub capacitor circuit arrayed in parallel to the capacitor circuit for serially connecting the output terminals of the two transistors; and at least one sub switch for controlling on/off state between the sub capacitor circuit and the output terminal, according to a predetermined control signal. Therefore, the magnitude of a degeneration impedance can be varied by controlling degeneration capacitance. Moreover, the variable degeneration impedance supply circuit can be advantageously applied to a voltage controlled oscillation circuit and a frequency divider circuit.