Dual Frequency Synthesizers for TDD LO Isolation and Phase Control
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Solution Overview
Problem
Current frequency synthesizer architectures for wireless devices, particularly in TDD mode, face challenges with complex signal routing, high power consumption, and performance degradation due to shared frequency synthesizers for receivers and transmitters, leading to increased coupling and phase errors.
Innovation Solution
A dual frequency synthesizer architecture is introduced, where separate frequency synthesizers are used for receivers and transmitters, allowing for independent operation and flexible divider ratios, reducing coupling and improving isolation, and enabling efficient power management by enabling/disabling synthesizers based on device activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a shared frequency synthesizer is used for both receiver and transmitter in TDD mode, then device complexity is reduced, but coupling and phase errors increase leading to performance degradation
Solution Approach 1:
The patent divides the shared frequency synthesizer into two separate frequency synthesizers: one dedicated to the receiver and another dedicated to the transmitter. This segmentation eliminates the coupling and phase errors that occur when a single synthesizer serves both functions, thereby improving signal quality while accepting increased device complexity.
2Use of energy by stationary object
If a shared frequency synthesizer is used for both receiver and transmitter, then power consumption is reduced, but receive-transmit isolation deteriorates
Solution Approach 1:
By segmenting the frequency synthesizer into separate receiver and transmitter units, the patent achieves better receive-transmit isolation. Each synthesizer can be independently controlled and optimized, preventing the harmful coupling effects that degrade isolation performance in shared architectures.
3Reliability
If separate frequency synthesizers are used for receiver and transmitter, then coupling is reduced and isolation is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by creating separate frequency synthesizer paths for receiver and transmitter operations. This architectural division successfully reduces coupling and improves isolation, though it inherently increases device complexity through additional components and signal routing.
4Measurement precision
If separate frequency synthesizers are used for receiver and transmitter, then phase errors are minimized, but signal routing complexity increases
Solution Approach 1:
The patent segments the frequency generation function into separate synthesizers for receiver and transmitter, which eliminates phase errors caused by shared resource contention. While this improves phase accuracy, it necessarily increases signal routing complexity due to the need for separate signal paths and synchronization mechanisms.
Data Source
AI summary
A dual frequency synthesizer architecture for a wireless device operating in a time division duplex (TDD) mode is disclosed. In an exemplary design, the wireless device includes first and second frequency synthesizers. The first frequency synthesizer generates a first oscillator signal used to generate a first/receive local oscillator (LO) signal at an LO frequency for the receiver. The second frequency synthesizer generates a second oscillator signal used to generate a second/transmit LO signal at the same LO frequency for the transmitter. The two frequency synthesizers generate their oscillator signals to obtain receive and transmit LO signals at the same LO frequency when the wireless device operates in the TDD mode.