This is the second post on Excel speed. The first part benchmarked the calculation speed of Excel 2003 versus Excel 2007 for various size arrays of formulas. This part analyzes the effect of formula complexity on the spreadsheet speed.

## Power Management: An Animated Buck Switching Regulator Model in Excel 2003

This is an animated model of a Buck voltage switching regulator in MS Excel 2003. Besides real time control of common parameters such as switch ON resistance, load current, load capacitance, output voltage (vout), input voltage (vbat) etc, the user can also run very specialized tests in which the output current and “vbat” can be modulated as either rectangular periodic or sinusoidal waves with adjustable frequency. This model is very fast (you can run it in adjustable “batch” mode) and extremely useful for real world transistor level design. The regulator can transition seamlessly between “continuous mode” and “skip cycle mode” (internally it does not make a difference between the two) and if you use a fast comparator it is intrinsically stable (a “switched-cap” comparator for instance) you can expect to design it having high efficiency at the transistor level (more than 96% flat over 3 decades of load currents). Enjoy!

## About the Speed of Spreadsheets #1

This post considers several aspects about improving the speed of spreadsheets in both MS Excel 2003 and 2007. In this first part, a “stopwatch” macro is described which, when incorporated in any of calculation loop, can measure the frequency your loop is executed. In this first part of the tutorial the macro was used to estimate the number of single formula calculations (as an array of “rand()” functions) executed per second by small, medium and large spreadsheets benchmarked for both 2003 and 2007 versions of MS Excel.

## A Gated Ring Oscillator Demo – Part#2

This is an upgrade from the first part in the sense that it can be adjusted to have more delay based inverters in the feedback (14). The animation is pretty much the same as in the first model, a virtual joystick controls the number of stages in the ring by horizontal movement and it can also control the RC delay constant by vertical movement.

## A Gated Ring Oscillator Demo – Part#1

An interactive animated demo of the gated ring oscillator in Excel 2003 based on the previous tutorial. ** This model stands out because of the real time schematic animation. **It is controlled by a virtual joystick which is generated using a chart with a macro assigned to it. To start the model click the red dot within the joystick chart. To stop the model you can click anywhere on the chart. While the model is active you can move the joystick head (which will stick to the mouse cursor). Vertical movement will control the RC constant of the delay stages and horizontal joystick head movement will change the number of delay stages within the loop. While the joystick head moves to the right, there are 7 inverters within the loop and the “Enable” signal is “chopped” which means the oscillator works in a discontinuous mode. A demo YouTube video will follow. Download the model, check it out and don’t forget to leave a comment.

## An Interactive Gated Ring Oscillator Tutorial – part #4

This is the fourth part of tutorial about making an interactive animated Excel model of a gated ring oscillator in MS Excel 2003. This section adds a joystick to the model which smoothly adjusts the RC delay constant (vertical movement) and the number of delay stages within the ring (horizontal movement). An additional function of the joystick is to control the gating signal (“Enable”) and place it either logic high or in a periodic mode with a period determined by the position of the same joystick. More detailed joystick theory you can find in this old post.

## An Interactive Gated Ring Oscillator Tutorial – part #3

This is the third part of tutorial about making an interactive animated Excel model of a gated ring oscillator in MS Excel 2003. This section deals with upgrading the model from a static table based one (with only 800 time steps) to a hybrid static-dynamic which is reasonably fast, yet it can run for an indefinite number of time steps.

## An Interactive Gated Ring Oscillator Tutorial – part #2

This is the second part of tutorial walking through the creation of an interactive animated Excel model of a gated ring oscillator in MS Excel 2003. This section is mainly concerned with the generation of the spin buttons, the macros assigned to them and the insertion of the worksheet functions modeling the NAND gate, the inverters and the delayless multiplexer. Towards the end of the presentation the first (static) version of the model is finished, the waveforms are plotted and the functionality tested.

## A Delay Based Animated Excel Model for Single-Stage Logic Gates – part#2

This is the second half of the delay based Excel model tutorial. In this part the final formulas are derived and implemented in Excel 2003. The model proves to be fast and reliable and it is actually fairly easy to create. For maintaining good speed no user defined functions have been used here.

## A Delay Based Animated Excel Model for Single-Stage Logic Gates – part#1

After learning how to model ideal logic gates in MS Excel 2003 it is time to attemp to create a delay based model. This first model is just a theoretical presentation about delay, how it can be explained and how it can be modeled with a minimum amount of formulas while keeping a reasonable precision. The presentation focuses on the basic CMOS inverter and it shows that for a basic single-stage logic gate the delay is mainly driven by the product between an equivalent Thevenin output impedance and the capacitance seen at the output of the gate, which obviously includes the input capacitance of the following stage and perhaps the transmission line capacitance.

## Introduction to Digital Electronics – a Simplified Model for Logic Gates – part#3

This is the third part of a tutorial about modeling logic gates in MS Excel 2003. This first model includes no delay or loading for the gates. This section creates user defined functions for each gate and uses these functions to upgrade the model. An auxiliary macro is created which measures the speed of the model in iterations/second. The model with user defined functions proves to be much slower than the model using plain built-in spreadsheet functions.

## Introduction to Digital Electronics – a Simplified Model for Logic Gates – part#2

This is the second part of a tutorial targeted at modeling logic gates in MS Excel 2003. The first part introduced the basic logic gates,, symbols and associated logic equations. This model includes no delay or loading for the gates. The following type of gates will are described: inverter, AND, NAND, OR, NOR, XOR (exclusive or) and XNOR. The tutorial has several parts and the last part builds up to a more complex and accurate model including effects such as: power supply voltage, output impedance and input capacitance (from which low pass fillter effects will be derived within the model). This is not an introduction to digital electronics. The reader should get somewhat familiar with the topic before attempting to build the models described here.

## Introduction to Digital Electronics – a Simplified Model for Logic Gates – part#1

This is the first part of a tutorial (self, 2, 3) about modeling logic gates in MS Excel 2003. This first model will include no delay or loading for the gates. The following type of gates will be described: inverter, AND, NAND, OR, NOR, XOR (exclusive or) and XNOR. The tutorial will have several parts and the last part will build up to a more complex and accurate model including effects such as: power supply voltage, output impedance and input capacitance (from which low pass fillter effects will be derived within the model). This is not an introduction to digital electronics. The reader should get somewhat familiar with the topic before attempting to build the models described here.

## An Animated Linear Feedback Shift Register (LFSR) as a Pseudo Random Pattern Generator in Excel 2003 – Part#3

This is the third part of a tutorial (1, 2, self) describing the creation of an animated Pseudo Random Number Generator model as a Fibonacci type Linear Feedback Shift Register in MS Excel 2003. This section charts the pseudo random series after converting it from binary 14-bit numbers into decimal numbers scaled within the interval [0,1). A correlation chart is then created, displaying the first half of the series function of the second half, with a small adjustable offset (between -200, and 200). Two simple macros are used, one for the manual offset adjustment and one for the animated offset adjustment. Changing the offset (either manually or using the animated macro) one can notice various not-so-random patterns for certain offset values.

## An Animated Linear Feedback Shift Register (LFSR) as a Pseudo Random Pattern Generator in Excel 2003 – Part#2

This is the second part of a tutorial (1, self, 3) describing the creation of an animated Pseudo Random Number Generator model as a Fibonacci type Linear Feedback Shift Register in MS Excel 2003. This part creates a very simple table type model based on combinatorial logic rather than a sequential type based on registers. Despite of the fact that this is not the way a real LFSR is built it is useful to go through this tutorial since it will give you more insight into the operation and modeling of such a circuit.

## An Animated Ray Tracing Model for Spherical Mirrors – video preview

This is a video preview to a previously posted ray tracing model.

## A 3D Flight Simulator – video preview

This is a preview to the 3D flight simulator model previously published on this blog.