Mode-Switched Spread Clocking for EMI-Safe Transceivers
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Solution Overview
Problem
Clocked electronic circuits in integrated transceiver systems radiate electromagnetic interference, causing transmission spurs and receiver desensitization due to digital noise from clock signals, which interferes with the operation of other electronic devices.
Innovation Solution
A clock spreading system that provides a periodic phase modulated spread clock output signal during receive mode and a pseudo-random phase modulated spread clock output signal during transmit mode, using a delay line logic device, clock gating latches, and a shift register to sequentially provide phase delay offset clock signals, thereby reducing electromagnetic interference by spreading the energy over nearby transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a clocked electronic circuit operates at a fixed clock frequency, then the circuit operates efficiently and reliably, but electromagnetic interference is concentrated at specific frequencies causing transmission spurs and receiver desensitization
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed-frequency clock signal to a dynamically varying clock signal. The clock frequency is modulated according to a spreading code sequence, causing the electromagnetic energy to be distributed across a range of frequencies rather than concentrated at a single frequency. This dynamic frequency variation resolves the contradiction by maintaining operational reliability while reducing harmful electromagnetic interference at any specific frequency.
Solution Approach 2:
The patent implements parameter changes by modifying the clock signal's frequency parameter over time according to a spreading code. The clock frequency is continuously adjusted within a defined range, transforming the electromagnetic spectrum distribution from a peaked concentration to a spread distribution. This parameter modulation effectively reduces receiver desensitization and transmission spurs while preserving circuit operational reliability.
2Object-affected harmful factors
If the clock signal frequency is spread over a range of frequencies, then electromagnetic interference is reduced, but the circuit complexity increases due to additional modulation components
Solution Approach 1:
The patent applies segmentation by dividing the clock signal generation into distinct functional components: a base clock signal generator, a spreading code sequence generator, and a frequency modulation stage. Each component performs a specific function, allowing the complex task of clock spreading to be broken down into manageable segments. This modular approach reduces overall system complexity while achieving the goal of reducing transmission spurs through frequency distribution.
Solution Approach 2:
The patent implements universality by designing the clock spreading mechanism to serve multiple functions simultaneously: it reduces transmission spurs, minimizes electromagnetic interference, and maintains timing synchronization. The same frequency modulation approach is applied across different operating modes, eliminating the need for separate specialized circuits for each function and thereby reducing overall device complexity.
3Reliability
If periodic phase modulation is used during receive mode, then receiver desensitization is mitigated, but the clock signal frequency stability varies during transmit mode
Solution Approach 1:
The patent applies local quality by implementing different clock modulation strategies tailored to specific operational modes. During receive mode, periodic phase modulation is applied to mitigate receiver desensitization, while during transmit mode, a different modulation approach is used to maintain frequency stability. This localized optimization allows each operational mode to have the clock characteristics best suited for its specific requirements, resolving the contradiction between receiver reliability and frequency stability.
Solution Approach 2:
The patent implements dynamics by making the clock modulation characteristics adaptive to the operational mode. The system dynamically switches between different modulation schemes based on whether the transceiver is in receive or transmit mode. This dynamic adaptation allows the clock signal to exhibit periodic phase modulation during reception for improved reliability, while maintaining appropriate frequency stability during transmission, thereby resolving the mode-dependent contradiction.
Data Source
AI summary
Clock spreading systems and methods are disclosed. In one embodiment of the invention, a clock spreading system is provided in an integrated transceiver system that comprises a base band control system and a transceiver coupled to the base band control system. The clock spreading system provides a spread clock output signal derived from a clock reference signal for clocking one of the base band control system and the transceiver. The clock spreading system is configured to provide a periodic phase modulated spread clock output signal during receiving of data in a receive mode and a pseudo-random phase modulated spread clock output signal during transmitting of data in a transmit mode.