RF Amplifying Stage With Parallel LNA Paths for Wide Dynamic Range

The patent employs dynamic switching between different signal paths (attenuator path and LNA path) based on input signal strength. The system transitions from a static attenuator configuration to a dynamic architecture where the attenuator is bypassed when processing weak signals, thereby maintaining low noise figure while preserving wide dynamic range through adaptive path selection.

The signal reception system is segmented into multiple parallel paths: an attenuator path for strong signals and an LNA path for weak signals. This segmentation allows each path to be optimized for its specific signal strength range, with the attenuator handling strong signals to prevent saturation and the LNA handling weak signals with low noise amplification, resolving the contradiction between dynamic range and noise figure.

The system dynamically selects between the attenuator path and LNA path based on signal strength requirements. For strong signals requiring attenuation and wide gain control, the attenuator path is activated. For weak signals requiring low noise amplification, the LNA path is activated. This dynamic path selection enables wide gain control range while maintaining low noise figure across different operating conditions.

The patent introduces a switching mechanism as an intermediary that routes signals through either the attenuator or LNA based on signal strength. This intermediary component enables the system to achieve wide gain control range through the attenuator when needed, while preserving low noise figure by routing weak signals through the LNA, effectively mediating between the conflicting requirements of gain range and noise performance.

The gain control function is segmented into two independent paths: an attenuator-based path for strong signal attenuation and a VGA-based path for weak signal amplification. Each path provides gain control capability, but they operate in different signal strength regimes. This segmentation enables extended overall gain control range without requiring a single complex VGA, as each segment can be simpler while collectively providing wide range control.

The system implements multi-functionality by having both the attenuator and VGA capable of providing gain control, but in different operating modes. The attenuator serves as a gain control element for strong signals (providing negative gain), while the VGA serves as a gain control element for weak signals (providing positive gain). This universal gain control capability across different paths extends the overall control range without requiring a single high-complexity VGA.

The system dynamically switches between the fixed-gain LNA path and VGA path based on input signal strength to maintain optimal linearity. For strong signals, the attenuator path with fixed-gain LNA is activated, providing highly linear attenuation and amplification. For weak signals, the LNA path is activated, providing low noise amplification with good linearity. This dynamic path selection ensures high linearity performance across the entire dynamic range, preventing the need to choose between complexity and linearity.

Each signal path is optimized for specific local operating conditions: the attenuator path with fixed-gain LNA is optimized for strong signal processing with high linearity requirements, while the LNA path is optimized for weak signal processing with low noise requirements. By assigning different quality characteristics to different paths and selecting the appropriate path based on signal strength, the system achieves high linearity performance across all operating conditions without requiring a single complex design.