## Archive for the ‘IC-Design-Study’ Category

### Book: Designing Analog Chips

Tuesday, August 18th, 2015

### 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.

 Archive:  Current-Source.7z     Program = LTSPICE Extract into directory.  Includes the required MOSFET library file.

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:

### Book: CMOS: Jacob Baker

Thursday, June 25th, 2015

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

### Operational Amplifier Design

Saturday, June 6th, 2015

### LTSPICE Phase Lock Loop Behavioral Simulation

Thursday, May 21st, 2015

### Integrated Circuit Procession

Saturday, May 9th, 2015

### Level shifter with low quiescent current

Friday, April 24th, 2015

A slightly different implementation:

### Charge Pump Articles – No Inductors Allowed

Wednesday, April 15th, 2015

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

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