This Cold Feedback web contains a collection of studies/projects on feedback on or due to cryogenic circuits. For example, the DAN and DAF projects use the DfMUX board ...

Sine Wave Mixer The transfer function of a sine wave mixer acting on broadband white noise is 1/sqrt(2). There is a factor of sqrt(2) from adding the left and right ...

Intro To DAN WARNING This page is out of date and essentially useless as of 8Jun2012. Where To Start Install DAN Firmware Installing the firmware means starting ...

Testing DAF Firmware Motivation The Digital Active Feedback (DAF) firmware is work in progress, mainly involving Adam, Graeme and Tijmen. The initial attempt at making ...

Strong Electrothermal Feedback Introduction I am trying to simulate a bolometer using Simulink (an addon to MATLAB). I start from equation (3.6) in Trevor's thesis ...

Gain Contraints For gain/impedance alone can consider the equivalent circuit for the tranformer of a capacitor, inductor and resistor in parallel. The resistance of ...

Active Feedback The following diagram shows the simplest possible reduction of the reading out of one bolometer. By approximation, we can group all the impedances ...

DAN Oscillations Introduction This document is out of date. When a discrete time integrator is added to the feedback loop, stability is greatly improved. In order ...

This page has the LC board design files May 2011 Altium files LCboard temp forAdam check 31May11.zip: LCboard temp forAdam check 31May11.zip Gerbers and fabrication ...

WinterlandUser 2011 05 13 This is the page that considers replacing the inductors on the LC board with spiral inductors Design goals We like to replace the 16uH ...

DAN Bode Plots Motivation Since DAN is an integral control loop, its transfer function can be written down analytically. DAN is linear, so the Bode plot contains ...

Loop Gain Equations Motivation For voltage biased TES bolometers, knowing the steepness of the transition is very important. The most natural parametrization of that ...

DAN Rework Motivation Matt noticed that DAN (in contrast to old style nulling) requires handling both the large "carrier" current through the bolometer and the small ...

Implementation The main purpose of this page is to plan the path forward (outline TODO items) on implementing digital active feedback (DAF). Firmware Tijmen wrote ...

DAN Effect on White Noise Motivation DAN is expected to locally reduce the white noise level by measuring it and canceling it out. This page investigates whether ...

DAN Transfer Function Motivation The current implementation of Digital Active Nulling (DAN) uses an integral control loop to null, i.e. cancel out the current through ...

Overlapping DAN channels Motivation Using DAN at 195 kHz with channels separated by less than 195 kHz may be an option we consider. Here, I show some of the effects ...

Discretization Noise in Digital Active Nulling Motivation Matt suggested that we might spread 1 LSB / sqrt(12) over the 12 kHz at which DAN operates, which would ...

Matt's Cold Transformer Design Notes This memo 20100505a is the current design in may 2010. MattDobbs 05 May 2010

DAN Bit Widths List of Bit Widths The output of the CIC2: 17 bits, The streamer will stream bits 16 downto 1. dan gain: 16 bits Accumulator, 16 bits ...

What is the optimum choice of Rbolo? We will assume for these calculations that we are operating in the middle of our useful bandwidth, i.e in the flat region. Also ...

Papers that I believe are useful for the cryogenic amplifier stage can be found here: Review of Scientific Instruments, 76, 124702 , 2005, A cryogenic voltage amplifier ...

Papers that discuss the reduction of winding capacitance on a wound magnetic component University power electronic education through and industrial battery charger ...

NoiseContraints The diagram below demonstrates what the feedback topology will look like. FeedbackDiagram.jpg: From this figure we can derive some noise gain ...

Specifications 1. Bandwidth of the final system should be at least in the range 50kHz to 500kHz. The bandwidth is required for our frequency multiplexed readout ...

Amplifier Noise gain derivation (General derivation applicable to squids and transformers) Before looking at our actual circuit diagram, consider the following diagram ...

Transformers in the cryostat Two transformers present On SQ1: 300:1 16 Ohm secondary (A38 B38) SQout 0.6 Ohm primary (A40 B40) On SQ8: 200:1 70nH/turn^2 10mH 6.3Ohm ...

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