Multi-Stage Pulse Shaping Network for RF Linearity and Noise Control
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Solution Overview
Problem
RF transmitters face a trade-off between energy efficiency and linearity, making it challenging to transmit data carrying RF signals with both high efficiency and high linearity, especially in mobile devices where RF amplifiers are physically distant from the power management circuit.
Innovation Solution
A multi-stage pulse shaping network (PSN) with a first stage coupled to a power management circuit and multiple second stages, each coupled to an RF amplifier, along with a reconfigurable filter circuit that uses switches to dynamically select filter characteristics based on load impedance, allowing for control of receive band noise and out-of-band emissions while maintaining linearity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a single-stage pulse shaping network is used, then the circuit complexity is low, but it cannot adequately control receive band noise and out-of-band emissions for supply modulation transmitters
Solution Approach 1:
The pulse shaping network is divided into multiple stages (first PSN stage and one or more second PSN stages) with each stage performing specific filtering functions. This segmentation allows better control of receive band noise and out-of-band emissions while managing circuit complexity through modular design
2Adaptability or versatility
If the RF amplifier is placed physically distant from the power management circuit, then the mobile device form factor is improved, but the control of supply modulation becomes challenging
Solution Approach 1:
The multi-stage PSN architecture allows the first stage to be coupled to the power management circuit while second stages are coupled to the RF amplifier, enabling physical separation suitable for mobile device form factors while maintaining effective supply modulation control through the distributed stage structure
Solution Approach 2:
The multi-stage pulse shaping network acts as an intermediary between the power management circuit and the RF amplifier, transmitting and conditioning the supply modulation signal across the physical distance while maintaining signal integrity and control effectiveness
3Use of energy by moving object
If energy efficiency is prioritized, then power consumption is reduced, but linearity deteriorates
Solution Approach 1:
The reconfigurable filter circuit dynamically adjusts its characteristics based on operating conditions, allowing the system to optimize between energy efficiency and linearity by adapting the filtering behavior to match the current supply modulation state and RF amplifier operating point
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
This solution enables the concurrent achievement of high efficiency and high linearity in RF transmitters, accommodating multiple RF amplifiers in a cost-effective mobile device form factor by filtering out undesirable frequency components and adjusting filter characteristics to suit changing impedance conditions.
Implementation Method 1
a multi-stage first pulse shaping network (PSN) having a first PSN stage (e.g. a so-called Stage A) having an input configured to be coupled to a power management circuit (PMC) and having an output and one or more second PSN stages (e.g. one or more so-called Stage Bs)
Implementation Method 2
a reconfigurable filter circuit that uses switches to dynamically select filter characteristics based on load impedance, allowing for control of receive band noise and out-of-band emissions while maintaining linearity and efficiency
Data Source
AI summary
In a discrete supply modulation system, a circuit includes a multi-stage pulse shaping network (PSN) having a first PSN stage having an input configured to receive variable bias supply signals from a power management circuit (PMC) and having an output coupled to one or more second PSN stages with each of the one or more second PSN stages having an output configured to be coupled to a supply (or bias) terminal of a respective one of one or more radio frequency amplifiers. Such an arrangement is suitable for use with transmit systems in mobile handsets operating in accordance with 5th generation (5G) communications and other connectivity protocols such as 802.11 a/b/g/n/ac/ax/ad/ay and is suitable for use with multiple simultaneous transmit systems including multiple-input, multiple-output (MIMO), uplink carrier aggregation (ULCA) and beamforming.