Balanced Cascode Frequency Quadrupler With Harmonic Notch Filtering
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Solution Overview
Problem
Existing high frequency multiplier circuits in the millimeter wave range face challenges with low conversion gain, increased chip area, and power consumption due to cascading stages, and are sensitive to temperature, supply voltage, and process variations, making it difficult to achieve high 4th harmonic generation efficiency.
Innovation Solution
A balanced cascode frequency quadrupler circuit with a common emitter and common base amplifier stages and notch filters is used to suppress second harmonics, increasing broadband odd harmonic suppression and conversion gain, while maintaining robustness against variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cascading stages are used to achieve high frequency multiplication, then the frequency multiplication capability is improved, but the chip area and power consumption increase
Solution Approach 1:
The patent combines the frequency doubling and frequency quadrupling functions into a single integrated circuit stage. The balanced cascode architecture integrates multiple amplifier stages (common emitter and common base) and filtering functions in one unified structure, eliminating the need for separate cascading stages and reducing overall chip area while maintaining high frequency multiplication capability.
2Productivity
If cascading stages are used to achieve high frequency multiplication, then the frequency multiplication capability is improved, but the power consumption increases
Solution Approach 1:
The patent merges multiple functions (amplification, frequency multiplication, and filtering) into a single integrated stage, reducing the total number of active components and their associated power consumption. The balanced cascode architecture achieves high frequency multiplication with fewer power-hungry stages compared to traditional cascading approaches.
3Device complexity
If traditional frequency multiplier circuits are used, then the circuit complexity is reduced, but the conversion gain is low and harmonic suppression is insufficient
Solution Approach 1:
The patent applies local quality by implementing a balanced cascode architecture with specific transistor configurations (common emitter and common base stages) that provide localized high gain and selective frequency multiplication. The notch filters are strategically placed to provide localized harmonic suppression at critical frequencies, achieving high conversion gain and harmonic suppression without requiring complex overall circuit architecture.
4Manufacturing precision
If the frequency quadrupler is designed for high performance, then the conversion gain and harmonic suppression are improved, but the sensitivity to temperature, supply voltage, and process variations increases
Solution Approach 1:
The patent employs feedback mechanisms through the balanced cascode architecture where the common base stage provides current feedback to stabilize the operation against variations. The differential balanced structure inherently provides feedback that compensates for temperature and process variations, maintaining high conversion gain and harmonic suppression performance across different operating conditions.
Solution Approach 2:
The patent uses parameter changes by designing the cascode stages with optimized transistor dimensions and biasing conditions that are less sensitive to process variations. The balanced differential structure allows for parameter tuning that maintains performance across temperature and supply voltage variations, achieving both high conversion gain and improved robustness.
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 achieves high conversion gain and suppression of unwanted harmonics, reducing chip area and power consumption, and maintaining design robustness across the 60-77 GHz frequency range with improved 4th harmonic power generation efficiency.
Implementation Method 1
a notch filter coupled to the input of said second amplifier stage and operative to suppress second harmonics generated by said first amplifier stage
Implementation Method 2
Frequency multipliers generally consist of a nonlinear circuit that distorts the input signal and consequently generates harmonics of the input signal
Data Source
AI summary
A frequency quadrupler comprises a balanced topology which increases broadband odd harmonic suppression. The frequency quadrupler is constructed in a cascode configuration which is a two-stage amplifier composed of a transconductance amplifier followed by a current buffer. The cascode is constructed with common emitter (CE) and common base (CB) stages which further improves the multiplier frequency response. The cascode configuration enables a notch filter to be placed between the common emitter and common base stages to reduce 2nd harmonic generation and thereby increase 4th harmonic output power, generation efficiency and conversion gain. To cancel 4th harmonic components at the input that may destructively interfere with the output signal, capacitors are placed at the input of the common emitter stage, which in conjunction with the parasitic base wire inductance, form a notch filter to short the 4th harmonic.