Digital Bias Control for Beamforming RF Circuits With Low SWAP
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Solution Overview
Problem
Existing phased antenna arrays face challenges in reducing size, weight, and power (SWAP) of bias circuitry, particularly in space applications, where efficient beamsteering is required without adding additional components or drawing excess current.
Innovation Solution
Employing programmable digital devices, such as FPGAs, to provide switchable power distribution and digital outputs for monolithic microwave integrated circuits (MMICs) in phased antenna arrays, enabling selective powering of beamsteering circuits with ultra-low power consumption and compact form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional bias circuitry is used for beamsteering control, then reliable RF signal control is achieved, but size, weight, and power consumption increase
Solution Approach 1:
The patent combines the digital output stage with the RF bias circuitry by using the digital output's pull-up transistor to directly provide the drain bias current to the MMIC amplifier. This merging eliminates the need for separate bias circuitry while maintaining control functionality, thereby reducing power consumption without sacrificing reliability.
Solution Approach 2:
The digital output pin is designed to serve multiple functions: it provides both the control signal for beamsteering and simultaneously serves as the power supply for the RF amplifier through its pull-up transistor. This multi-functionality reduces the overall component count and power consumption while maintaining reliable control.
2Adaptability or versatility
If additional switching circuitry is added for selective powering, then control flexibility is improved, but device complexity increases
Solution Approach 1:
The digital output pin's internal pull-up transistor automatically provides the switching function for selective powering. When the digital output is driven high, the transistor conducts and powers the RF amplifier; when driven low or tri-stated, the transistor turns off and disables the amplifier. This self-service mechanism eliminates the need for external switching circuitry while maintaining control flexibility.
Solution Approach 2:
The control signal path and power delivery path are merged into a single digital output pin. The same pin that provides logic control also provides power switching, eliminating the need for separate switching components and reducing overall system complexity.
3Ease of operation
If separate bias circuitry is used for each MMIC, then individual control is achieved, but component count and space increase
Solution Approach 1:
Multiple MMIC amplifiers share a common digital output pin for bias control. The pull-up transistor's drain current is distributed among multiple MMICs, allowing individual control of each amplifier's power state through software control of the single digital pin while reducing the overall component count.
Solution Approach 2:
A single digital output pin serves multiple MMIC amplifiers simultaneously, providing both control signaling and power delivery to multiple devices. This multi-functional approach reduces component count while maintaining the ability to individually control each amplifier's operational state.
Data Source
AI summary
Methods, systems, and devices for biasing radio frequency (RF) circuits with digital controls are described. An example antenna subsystem may include a plurality of beamforming circuits configured to adjust component RF signals for antenna elements. Each beamforming circuit may include phase shifters, amplifiers, and a supply input for the amplifiers. The antenna subsystem may further include a programmable digital device comprising a beam steering input and a control mode input. The antenna subsystem may further include a plurality of digital outputs, including a first set configured to provide phase adjustment control signals to the phase shifters of at least a subset of the beamforming circuits based at least in part on a beam direction value and a second set configured to directly power supply inputs of the subset of the plurality of beamforming circuits based at least in part on a control mode value.