Archive for the ‘SPICE’ Category

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.



Output Current


Supply Current

Ultra Low Current Band Gap References Using NanoAmps of Current with Good MonteCarlo Results

Tuesday, August 11th, 2015

If you need a voltage reference when doing energy harvesting it is very helpful have a band gap reference that uses very little current.  This topology uses “Self Cascode Mosfet”  abreviated as SCM.  The LTSPICE design uses 4.5 nano Amperes and outputs a 0.6 Volt reference voltage.

Research Links



   Archive: Voltage-Reference.7z      Program = LTSPICE

Extract into directory.  Includes the required MOSFET library file.


LTSPICE Analysis

Vref versus Temperature


Voltage reference current consumption versus temperature

Monte Carlo Analysis with Cadence

  •  Note how tight the voltage control is
  • Current usage = 1 nAmpere

MC_Voltage-Reference_V09 Schem_Voltage-Reference_V09


4 Phase Charge Pump Clock Generators

Monday, July 13th, 2015

Document Links

Book: CMOS: Jacob Baker

Thursday, June 25th, 2015

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

Research Links

Adding Series 4000 CMOS library to LTSPICE

Thursday, June 25th, 2015

Research Links

Operational Amplifier Design

Saturday, June 6th, 2015


  Archive: OTA-Folded-Cascode.7z








Pulse Generation and Signal Conditioning Circuits

Friday, May 29th, 2015

Research Links

Pulse Generation Circuits

  • Dual edge delay
  •  Leading edge delay
  • Trailing edge delay
  • Dual edge detector / frequency doubler
  • Leading edge detector
  • Trailing edge detector

Level shifter with low quiescent current

Friday, April 24th, 2015


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



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%.

LTSpice Power of Ten Exponent Units

Sunday, March 8th, 2015

K = k = kilo = 103
‹ MEG = meg = 106
‹ G = g = giga = 109
‹ T = t = terra = 1012
‹ M = m = milli = 10-3
‹ U = u = micro = 10-6
‹ N = n = nano = 10-9
‹ P = p = pico = 10-12
‹ F = f = femto = 10-15