Cascaded LO Distribution Network Without Power Splitting
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Solution Overview
Problem
The increasing operating frequencies in electronic devices pose challenges for local oscillator (LO) signal distribution, including increased power consumption, phase noise requirements, and layout complexity, which limit flexibility and scalability in millimeter-wave transceivers, particularly due to the need for power splitting networks and metal cross-overs that can cause signal coupling and gain/phase imbalance.
Innovation Solution
A cascaded LO signal distribution network where the TX mixer and RX LO buffer are coupled on the same signal path, eliminating the need for power splitting circuitry and reducing routing crossover, allowing the LO generation network to be placed outside the TX and RX chains, thereby simplifying layout and reducing component count and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power splitting network is used to distribute LO signals to TX and RX mixers, then the LO signal can be delivered to both chains, but the device complexity and layout area increase
Solution Approach 1:
The patent extracts the LO buffer from the traditional power splitting network architecture. Instead of using a buffer before the power splitter, the LO buffer is placed after the power splitter, allowing the LO signal to be distributed to both TX and RX chains without requiring an additional buffer stage. This reduces device complexity while maintaining reliable LO signal distribution.
Solution Approach 2:
The power splitting network is designed to serve dual purposes: distributing LO signals to both TX and RX chains while also providing impedance matching. By making the power splitter multi-functional, additional components are eliminated, reducing overall device complexity while maintaining reliable signal distribution.
2Ease of operation
If metal cross-overs are used in LO signal routing, then the LO signal can be routed throughout the device, but spurious coupling and gain/phase imbalance increase
Solution Approach 1:
The patent transitions from planar routing with metal cross-overs to three-dimensional vertical interconnect structures. By routing LO signals through vertical vias and stacked configurations, the design eliminates the need for metal cross-overs that cause spurious coupling, while still achieving comprehensive signal distribution across the device.
3Power
If additional buffer stages are added to LO distribution network, then the LO signal power is sufficient for distant locations, but power consumption increases
Solution Approach 1:
The patent removes the redundant LO buffer stage from the traditional architecture. By placing the LO buffer after the power splitter rather than before it, the design eliminates one buffer while still providing sufficient LO signal power to both TX and RX chains through the power splitting network's inherent signal distribution capability.
Solution Approach 2:
The power splitting network is designed to provide sufficient signal power to distant locations without requiring additional buffer stages. The network itself serves the function of power distribution, making the system self-sufficient and eliminating the need for extra buffers that would increase power consumption.
4Ease of operation
If the LO generation network is placed inside the TX and RX chains, then the LO signal is readily available, but layout flexibility and scalability are limited
Solution Approach 1:
The patent segments the LO distribution function from the TX and RX signal chains. By creating a separate, dedicated LO distribution network with its own buffer and power splitter, the design allows independent optimization of the LO path while maintaining LO signal availability for both chains, thereby improving layout flexibility and scalability.
Data Source
Figure 1A
Figure 1B
Figure 2A~2C
AI summary
Systems, methods, and circuitries are provided for a local oscillator (LO) signal distribution. An exemplary LO distribution network includes a common LO buffer configured to buffer an LO signal, a receive (RX) LO buffer, and a transmit (TX) mixer in a cascaded arrangement. The RX LO buffer is configured to receive the LO signal and buffer the LO signal and to provide the LO signal to an RX mixer. A first LO signal line and a second LO signal line are configured to conduct the LO signal from the common LO buffer to the RX LO buffer. The RX LO buffer is coupled to the first LO signal line and the second LO signal line. The TX mixer is also coupled to the first LO signal line and the second LO signal line.