Programmable Transconductor Modes for Bandwidth and Flicker Noise
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Solution Overview
Problem
Transconductor circuits face challenges in simultaneously reducing flicker noise and maintaining suitable bandwidth, as large-area devices that minimize flicker noise are not compatible with wide-bandwidth applications due to high capacitance, which restricts their use in both narrow and wide-bandwidth applications.
Innovation Solution
A transconductor circuit with a programmable tradeoff between bandwidth and flicker noise is implemented, featuring a switch arrangement that adjusts coupling between input and output ports and transistors to operate in either a low-noise mode with higher capacitance or a wide-bandwidth mode with lower capacitance, allowing for flexible operation across different signal bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If large-area devices are used to reduce flicker noise, then flicker noise is reduced, but input capacitance increases making the circuit unsuitable for wide-bandwidth applications
Solution Approach 1:
The transconductor circuit employs switch arrangements that dynamically reconfigure the coupling between input/output ports and transistor arrangements, enabling the circuit to switch between different operational modes (first mode with larger input capacitance for narrow-bandwidth low-noise applications, and second mode with smaller input capacitance for wide-bandwidth applications), thus making the circuit adaptable to different bandwidth requirements while managing flicker noise appropriately for each application type
2Object-affected harmful factors
If large-area devices are used to reduce flicker noise, then flicker noise is reduced, but the circuit cannot be tuned to wide-bandwidth signals
Solution Approach 1:
The circuit uses switch arrangements to dynamically change the effective area of the transistor arrangement by reconfiguring which transistors are coupled to the input and output ports, allowing the circuit to switch between a first configuration with larger effective area (lower flicker noise) and a second configuration with smaller effective area (higher flicker noise but wider bandwidth capability), thus enabling the circuit to be tuned for different signal bandwidths as needed
3Object-affected harmful factors
If a single semiconductor product is designed for narrow-bandwidth applications with reduced flicker noise, then it performs well in narrow-bandwidth applications, but it cannot be used in wide-bandwidth applications
Solution Approach 1:
The transconductor circuit is designed with multiple transistor arrangements and switch arrangements that enable it to perform multiple functions: it can operate in a first mode with larger input capacitance optimized for narrow-bandwidth applications with low flicker noise requirements, and switch to a second mode with smaller input capacitance optimized for wide-bandwidth applications, thus making a single semiconductor product universally applicable to both narrow-bandwidth and wide-bandwidth applications
Solution Approach 2:
The circuit incorporates switch arrangements that allow dynamic reconfiguration of the transistor coupling, enabling the same physical circuit to present different electrical characteristics (different input capacitances) depending on the operational mode, thus allowing a single product to adapt to different application requirements rather than requiring separate products for different bandwidth applications
Data Source
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AI summary
Transconductor circuits with programmable tradeoff between bandwidth and flicker noise are disclosed. An example circuit includes an input port, an output port, a plurality of transistors, and a switch arrangement that includes a plurality of switches, configured to change coupling between the input port, the output port, and the transistors to place the transconductor circuit in a first or a second mode of operation. An input capacitance of the transconductor circuit operating in the first mode is larger than when the transconductor circuit is operating in the second mode. In the first mode, having a larger input capacitance results in a decreased flicker noise because the amount of flicker noise is inversely proportional to the input capacitance. In the second mode, having a smaller input capacitance leads to an increased flicker noise but that is acceptable for wide-bandwidth applications because wide-bandwidth signals may be less sensitive to flicker noise.