Archive for the ‘IC-Design-Study’ Category

Book: Designing Analog Chips

Tuesday, August 18th, 2015

Research Links

1 nanoamp Current Source with No Resistors Using Self Cascode MOSFET

Thursday, August 13th, 2015

Note the 500M Ohm resistor is only to test the current reference.  It would be replaced by your application circuit.

Research Links

 Archive:  Current-Source.7z     Program = LTSPICE

Extract into directory.  Includes the required MOSFET library file.

Current-Source

 

Output Current

 

Supply Current

Monte Carlo Analysis with Cadence and the XFAB Design Kit

Wednesday, July 8th, 2015

Getting Monte Carlo analysis to work on Cadence can be a bit of a puzzle given how Cadence is a ball of various software tools stuck together with spit.  You have have seen the following intermodal nastygram:

ADEXL-5052 Monte Carlo run stopped because no statistical data generated for the test

Research Links

Book: CMOS: Jacob Baker

Thursday, June 25th, 2015

Jacob Baker maintains CMOSedu.com.  There is a large amount of useful material there.

Research Links

Operational Amplifier Design

Saturday, June 6th, 2015

Links

  Archive: OTA-Folded-Cascode.7z

 

OTA-Folded-Cascode-Schematic

 

OTA-Test-Circuit

 

OTA-Test-Circuit-AC-Analysis

 

LTSPICE Phase Lock Loop Behavioral Simulation

Thursday, May 21st, 2015

Behavioral Phase Lock Loop Schematic file

Integrated Circuit Procession

Saturday, May 9th, 2015

Research Links

Level shifter with low quiescent current

Friday, April 24th, 2015

ADI_Logo_AWP_small_112x44[1]

Analog Devices Wiki

Research Links

A slightly different implementation:

 

 

Charge Pump Articles – No Inductors Allowed

Wednesday, April 15th, 2015

XFAB Links

 

XFAB PhotoDiode Cross Sections png

XFAB has integrated photo diodes in the XH018 process.  However it was difficult to find the scaling factor for the light input pin on the photo diode schematic symbol.  The only place I have found it thus far is in the photo diode model:

The photodiode light input is a third terminal on the diode symbol. In order to do a simulation one must know how light intensity scales to light input terminal voltage. This information was discovered in the comments one of the photodiode library files.

Excerpt from file: dphoa.scs

* TERMINALS: anode=PSUB, cathode=DNWELL, lpower=lpower[1uV==1uW] 
* VARIABLES: area[m2], perimeter[m], wavelength[1==1um] 
* TNOM = 27 deg C; TEMP=27 deg C 

 

Paper Links

Block-Diagram-0p35-Solar-Energy-Scavenger

Solar-Cell-Circuit-Model

A 0.35 um CMOS Solar Energy Scavenger with Power Storage Management System

 

 

Cross couple voltage doubler.

Design of Very Low Voltage CMOS Rectifier Circuits  – Bulk connection is very important in voltage multipliers.  In a Dickson charge pump DTMOS connection is the one that works best.  That assumes you are using isolated transistors so you do not end up with elevated theshold voltages.

Dickson model above simulates the action of the main line of the voltage multiplier but does not cover the power required by the clock inverters that drive the 2 phases.  Thus it does not apply for over all efficiency calculations.

 

The current of the 5V section of the level shifter is too high for very low consumption circuits.  My simulations had it at 10uAmp @ 1MHz.

 

This charge recycling scheme does not work if the stray capacitance is negligible compared to the pump capacitance. My lack of understanding lead me to try using it with my test design simulations. When no difference in current consumption showed up I had to scatch my head.

 

Voltage Regulation for Energy Scavenging

  

Circuit Implementation Notes

  • Area Efficiency Improvment of CMOS Charge Pumps:  If p is the ratio of stray capacitance to desired capacitance (Cp  p Ca) and is determined by the type of capacitors used. For double poly capacitors, this value is usually between 10 and 20 percent. Thin oxide MOS capacitors provide 5-15% stray capacitance, with a higher capacitance per unit area than double poly capacitors. For poly-metal capacitors, p can be as much as 20-50%.

Low Voltage AC to DC Converter Articles

Wednesday, January 14th, 2015

Links

 

XFAB