WiGig Baseband Amplifier With Decoupled Gain and Filter Bandwidth
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Solution Overview
Problem
Conventional WiGig baseband signal-processing systems face challenges in achieving sufficient gain for maximum signal-to-noise ratio, attenuating out-of-band signals, and accommodating high dynamic range input signals while maintaining high linearity, often resulting in high power consumption and sub-optimal design due to the interdependence of filter bandwidth and gain settings.
Innovation Solution
A circuit comprising a Sallen-Key filter with a source follower and a programmable-gain amplifier, where the programmable gain is achieved via adjustment of the current mirror copying ratio, decoupling bandwidth from gain settings, and using a source follower to extend high-frequency behavior and reduce power consumption, while ensuring independent filter bandwidth and gain control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional baseband system uses dedicated amplifiers in closed-loop configuration for filtering and separate programmable gain amplifiers, then sufficient gain and signal-to-noise ratio are achieved, but power consumption increases and the interdependence of filter bandwidth and gain settings creates sub-optimal design
Solution Approach 1:
The patent combines the filter and programmable gain amplifier into a single integrated circuit device, merging previously separate dedicated amplifiers and filter stages. This integration eliminates redundant components and reduces overall power consumption while maintaining the required signal-to-noise ratio through shared circuitry and coordinated design of the Sallen-Key filter and programmable-gain amplifier stages.
Solution Approach 2:
The integrated circuit device performs multiple functions within a single system: filtering (bandwidth control) and amplification (gain control) are achieved in one device rather than requiring separate dedicated components. The Sallen-Key filter and programmable-gain amplifier work together to provide both frequency selection and signal amplification, reducing the total number of active components and their associated power consumption.
2Adaptability or versatility
If conventional systems use separate dedicated amplifiers for filtering and gain, then filter bandwidth and gain can be controlled, but the settings are interdependent leading to sub-optimal design
Solution Approach 1:
The patent segments the control functions by providing independent control mechanisms for filter bandwidth and amplifier gain. The Sallen-Key filter stage allows independent bandwidth adjustment while the programmable-gain amplifier stage provides independent gain control, eliminating the interdependence present in conventional designs. This segmentation is achieved through separate control inputs and independently adjustable parameters in each stage.
Solution Approach 2:
The circuit incorporates dynamically adjustable parameters where both the filter bandwidth and amplifier gain can be independently varied without affecting each other. The programmable-gain amplifier uses adjustable impedance elements that allow real-time gain control independent of the filter's bandwidth settings, enabling flexible adaptation to different signal processing requirements without redesign.
3Power
If conventional designs use operational amplifiers in Sallen-Key filters, then high gain is achieved, but linearity deteriorates for high dynamic range input signals
Solution Approach 1:
The patent introduces an intermediary approach by using the Sallen-Key filter configuration with specific impedance arrangements that provide high gain while maintaining linearity. The filter's passive components (resistors and capacitors) act as intermediaries that shape the signal before amplification, reducing the burden on the active amplifier stage and improving overall linearity for high dynamic range signals.
Solution Approach 2:
The circuit employs parameter optimization in the Sallen-Key filter design, adjusting component values and impedance ratios to achieve the optimal balance between gain and linearity. By carefully selecting filter component parameters and amplifier operating points, the design achieves high gain while maintaining excellent linearity characteristics for WiGig baseband signal processing.
Data Source
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AI summary
A circuit comprises a Sallen-Key filter, which includes a source follower that implements a unity-gain amplifier; and a programmable-gain amplifier coupled to the Sallen-Key filter. The circuit enables programmable gain via adjustment to a current mirror copying ratio in the programmable-gain amplifier, which decouples the bandwidth of the circuit from its gain settings. The programmable-gain amplifier can comprise a differential voltage-to-current converter, a current mirror pair, and programmable output gain stages. The Sallen-Key filter and at least one branch in the programmable-gain amplifier can comprise transistors arranged in identical circuit configurations.