Dual-Control VCO Circuit for Wideband Multi-Band Tuning
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Solution Overview
Problem
Conventional cross-coupled voltage controlled oscillators (VCOs) operating in microwave or millimeter-wave frequency bands are limited to single-band operations, making them unsuitable for multi-band operations in phase-locked loop circuits for radio communication and clock and data recovery circuits for optical communication, and their complexity increases with attempts to achieve multi-band capabilities.
Innovation Solution
A voltage controlled oscillator configuration with a first frequency control terminal to adjust output frequency through variable capacitance and a second frequency control terminal to adjust the center frequency by altering the transistor characteristics, allowing for multiple continuous input/output characteristics across a wider bandwidth using a simple circuit design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional cross-coupled voltage controlled oscillator is used with a single control terminal, then the circuit configuration remains simple, but the oscillator is limited to single-band operations and cannot achieve multi-band capabilities
Solution Approach 1:
The patent applies multi-functionality by providing two control terminals with distinct functions: the first control terminal adjusts the output frequency within a band using variable capacitance, while the second control terminal adjusts the center frequency by altering transistor characteristics. This dual-control mechanism enables the single oscillator circuit to perform multi-band operations across different frequency ranges without requiring separate oscillator circuits for each band, thus achieving versatility while maintaining circuit simplicity.
Solution Approach 2:
The patent applies dynamics by making the transistor characteristics adjustable through the second control terminal. The transistor's operating point and characteristics can be dynamically changed by varying the control voltage at the second terminal, which in turn dynamically adjusts the center frequency of the oscillation. This dynamic characteristic adjustment allows the oscillator to adapt to different frequency bands on demand.
2Adaptability or versatility
If attempts are made to achieve multi-band capabilities in conventional VCOs, then the frequency range expands, but the circuit complexity increases
Solution Approach 1:
The patent applies multi-functionality by providing two control terminals with distinct functions: the first control terminal adjusts the output frequency within a band using variable capacitance, while the second control terminal adjusts the center frequency by altering transistor characteristics. This dual-control mechanism enables the single oscillator circuit to perform multi-band operations across different frequency ranges without requiring separate oscillator circuits for each band, thus achieving versatility while maintaining circuit simplicity.
3Adaptability or versatility
If the output frequency is adjusted using variable capacitance only, then the frequency tuning is achieved, but the input/output characteristics remain limited to a single band
Solution Approach 1:
The patent applies multi-functionality by providing two control terminals with distinct functions: the first control terminal adjusts the output frequency within a band using variable capacitance, while the second control terminal adjusts the center frequency by altering transistor characteristics. This dual-control mechanism enables the single oscillator circuit to perform multi-band operations across different frequency ranges without requiring separate oscillator circuits for each band, thus achieving versatility while maintaining circuit simplicity.
Solution Approach 2:
The patent applies parameter changes by modifying two key parameters: the capacitance value (through the first control terminal) and the transistor characteristics (through the second control terminal). By simultaneously controlling these two parameters, the oscillator achieves continuous input/output characteristics across multiple frequency bands, transforming a single-band device into a multi-band device through parameter modulation rather than structural redesign.
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 multi-band operations with continuous input/output characteristics across a wider bandwidth, simplifying the circuit design and maintaining stability against power supply and noise variations, while avoiding output power fluctuations.
Implementation Method 1
variable capacitance 8a, 8b and inductor 9a, 9b. With changing control voltage Vcont supplied to control terminal 2, the capacitances of variable capacitances 8a, 8b change.
Implementation Method 2
LC tank 10a, 10b is a resonant circuit including variable capacitance 8a, 8b and inductor 9a, 9b.
Implementation Method 3
The cross-coupled voltage controlled oscillator of this conventional example is configured as described above and as a result, a positive feedback can be provided. At this time, cross-coupled transistors 5a, 5b allow electricity to travel through each other.
Data Source
AI summary
A voltage controlled oscillator of the present invention includes power supply terminal (101), control terminal (2) for controlling an output frequency, output terminals (3a, 3b), cross-coupled transistors (5a, 5b), capacitances (6a, 6b, 7a, 7b), LC tanks (10a, 10b), resistor (117), grounding capacitance (18) and center frequency control circuit (16). Center frequency control circuit (16) includes resistors (11a, 11b), grounding capacitance (12), center frequency control terminal (4) for controlling a center frequency of the output frequency, and voltage-divider circuit (15). Resistors (11a, 11b) are connected to the base terminals of cross-coupled transistors (5a, 5b), the other ends of resistors (11a, 11b) are connected to each other, and, to this connecting point, one end of grounding capacitance (12) and one end of voltage-divider circuit (15) are connected. The other end of voltage-divider circuit (15) is connected to center frequency control terminal (4).