Multi-Stage RF Switch Circuit With Dynamic Bulk Bias Feedback
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Solution Overview
Problem
Existing RF switch circuits face challenges in achieving high voltage withstanding and linearity, particularly in high-band RF signals, leading to attenuation and nonlinearity issues.
Innovation Solution
The RF switch circuit design includes multiple stages of switch transistor units connected in series, with each stage comprising a switch transistor, gate bias resistor, bulk bias resistor, path resistor, mirror resistor, and a dynamic adjustment unit. The dynamic adjustment unit connects the bulk of each switch transistor to its intermediate terminal and balances voltage across the mirror resistor chain, improving voltage distribution and reducing nonlinearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmission power of the RF signal is increased to meet stability requirements in high band, then the RF signal stability is improved, but the RF switch circuit requires higher withstanding power capability
Solution Approach 1:
The RF switch circuit is divided into multiple stages of switch transistor units connected in series. Each stage includes a switch transistor with its own gate bias resistor, bulk bias resistor, path resistor, and dynamic adjustment unit. This segmentation distributes the voltage and power stress across multiple components rather than concentrating it in a single transistor, thereby improving the overall withstanding power capability while maintaining RF signal stability.
2Power
If the RF switch circuit withstanding power capability is increased to handle high power RF signals, then the power handling capability is improved, but the linearity of the RF switch circuit deteriorates due to increased nonlinearity
Solution Approach 1:
A dynamic adjustment unit is introduced in each stage that includes a bulk bias resistor connected to the bulk of the switch transistor and a mirror resistor chain. The dynamic adjustment unit provides feedback control by adjusting the bulk bias voltage based on the voltage across the mirror resistor chain, which reflects the current through the switch transistor. This feedback mechanism compensates for nonlinear effects and maintains linearity even when handling high power RF signals.
Solution Approach 2:
The invention dynamically changes the bulk bias voltage parameter to maintain linearity. The bulk bias voltage is adjusted through the dynamic adjustment unit based on operating conditions, allowing the circuit to adapt and maintain optimal linearity characteristics across different power levels. This parameter adjustment counteracts the nonlinear effects that would otherwise occur at high power levels.
3Reliability
If multiple stages of switch transistor units are connected in series to improve voltage withstanding capability, then the voltage withstanding capability is improved, but the device complexity increases
Solution Approach 1:
Each stage of the RF switch circuit uses identical components with the same circuit configuration, including the switch transistor, gate bias resistor, bulk bias resistor, path resistor, and dynamic adjustment unit. This universal design allows the same circuit block to be replicated multiple times in series, improving voltage withstanding capability while keeping the design manageable through repetition of a standardized unit rather than creating increasingly complex unique circuits.
Solution Approach 2:
The mirror resistor chain connects the dynamic adjustment units across stages, creating an equipotential reference system. The mirror resistors are arranged such that they provide a common reference potential that simplifies the analysis and design of each stage. This equipotential approach reduces the complexity by providing a consistent reference framework across all stages.
Data Source
AI summary
A high-linearity radio frequency switch circuit, a chip and an electronic device having same, which can relieve the nonlinear problem of radio frequency switch circuits, and improve the withstand power and the voltage withstanding capability of same. The radio frequency switch circuit consists of multiple stages of switching transistor units connected in series, wherein of each switching transistor (Mi), a gate is connected to a corresponding gate bias resistor (RAi), a drain and a source are separately connected to a corresponding via resistor (Rdsi), and a body is connected to a corresponding body bias resistor (RBi); the gate bias resistor (RAi) and the body bias resistor (RBi) in a switching transistor unit of each stage are connected in series; mirror resistors (Rci) are successively connected in series to form a mirror resistor chain.