25-11-2025: CS stage noise performance optimization#
Lecture: EE4109-5
Location: Hall Ampere (36.HB.01.670)
Time: 15:45 - 17:30
Design of CS stage noise behavior#
Input stage design
Presentation
The input-referred noise sources of a feedback amplifier at best equal those of its controller. This is the case in non-energic feedback amplifiers. Passive feedback elements increase the controller's input-referred noise sources' contribution to the amplifier noise. When their impedance has a nonzero real part, they contribute noise themselves.
The controller's input-referred noise sources are at best equal to those of its input stage. This is the case in which the transmission parameters of the input stage approach those of a nullor. The best nullor approximation is a CS stage, which makes it the preferred controller input stage.
The presentation Noise Design of the Input Stage MOS in Feedback Amplifiers discusses the design of the input stage of a negative feedback amplifier such that its noise contribution stays within budgeted limits.
Presentation in parts
Download
Please download the SLiCAP MOS noise design automation script
Group exercise (until lecture 9: 09-12-2025)#
Design a feedback amplifier configuration for the hearing loop receive amplifier using a nullor as a controller.
Create a network model of the source
Create a network model of the load
Design a feedback configuration that accurately performs the required source-load transfer over the desired frequency range
Assign a (minor) budget to the contribution of the feedback elements to the weighted output noise
Assign a budget to the contribution of the feedback elements to the controller's current-drive requirements
Assign values to the feedback network elements such that their contribution to the weighted RMS output noise and their contribution to the controller's current-drive requirements are within the assigned budgets
You can use SLiCAP for this purpose: cascade your amplifier with a DIN-A filter for evaluation of the noise performance and the assignment of feedback element values.
Assign a budget for the contribution of the controller's input stage to the weighted output noise
Design an NMOS or PMOS as the controller input stage of the amplifier, with the assigned values of feedback elements