Programmable Source Follower Attenuator for Wideband Gain Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-speed serial systems face issues with non-linear distortion due to large amplitude input signals, necessitating an attenuator design that can scale down signal magnitude while meeting wideband requirements.
Innovation Solution
A signal attenuator circuit utilizing a complementary source follower circuit and a programmable gain-tuning array circuit, comprising N-type and P-type transistors, with a programmable gain-tuning array that adjusts attenuator gain through selectively enabled cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amplitude input signal is received by an active device (amplifier) of the receiver, then the signal can be processed, but the output signal suffers from non-linear distortion
Solution Approach 1:
The patent introduces a complementary source follower circuit as an intermediary component between the input signal and the active device. This circuit acts as a buffer that isolates the active device from large amplitude input signals, preventing non-linear distortion while maintaining signal processing capability. The source follower circuit transfers the signal to the active device in a controlled manner, serving as a protective intermediary layer.
Solution Approach 2:
The patent converts the potentially harmful large amplitude input signal into a beneficial feature by using it to control the complementary source follower circuit. The large signal amplitude becomes useful for driving the follower circuit, which then provides a clean, linearized version of the signal to the active device. The harmful distortion is transformed into a useful control mechanism.
2Object-generated harmful factors
If an attenuator design is implemented to scale down signal magnitude, then non-linear distortion is reduced, but the device complexity increases due to programmable gain-tuning array
Solution Approach 1:
The patent divides the attenuator function into multiple segments: a complementary source follower circuit for basic signal buffering and a programmable gain-tuning array with multiple cells for precise attenuation control. Each cell in the array can be independently controlled, allowing the complex attenuation function to be broken down into manageable, modular units that can be selectively activated.
Solution Approach 2:
The patent implements dynamic gain control through the programmable gain-tuning array, where the attenuation level can be adjusted in real-time based on signal conditions. The circuit transitions from a fixed attenuator design to a dynamic, adaptable system that can optimize its attenuation level programmatically, reducing distortion while maintaining flexibility.
3Adaptability or versatility
If a complementary source follower circuit is used, then wideband performance and low output impedance are achieved, but power consumption increases due to always-enabled transistors
Solution Approach 1:
The complementary source follower circuit serves multiple functions simultaneously: it provides wideband signal buffering, maintains low output impedance, and enables precise gain control through the integrated programmable array. This multi-functional design reduces the need for separate circuits, optimizing power efficiency while maintaining performance across wide frequency ranges.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A signal attenuator circuit (100) includes a complementary source follower circuit (102) and a programmable gain-tuning array circuit (104). The complementary source follower circuit (102) includes a first transistor and a second transistor. A control terminal of the first transistor is biased by a first bias voltage and receives an input signal of the signal attenuator circuit (100). A control terminal of the second transistor is biased by a second bias voltage and receives the input signal. The first transistor and the second transistor include an N-type transistor and a P-type transistor that are always enabled during a period in which the signal attenuator circuit is in operation. The programmable gain-tuning array circuit (104) is coupled to an output node of the complementary source follower circuit (102), and includes parallel connected cells, each being selectively enabled to adjust an attenuator gain of the signal attenuator circuit (100).