PICOAMMETER TYPE CP13

 

     

1.   INTRODUCTION

The CP13 is a combined DC ammeter and generator for use over the current range 
12x10^-3A FSD to 12x10^-14A FSD in 23 ranges.  An additional range enables charge to be measured with an FSD of 12pC.  As an ammeter, it maintains its virtual earth input within 50mV of earth for signals from zero to FSD and has an equivalent input drift typically less than 50mV over 1 hour after an initial 10 minutes settling period.  As a generator, it has an equivalent source voltage of greater than 1kV and will tolerate a load voltage deviation from earth of more than 1.5V.

 

2.   PERFORMANCE SPECIFICATION 

(At 20^oC except where otherwise stated and after 10 minutes settling period)

 

As the same measuring components are used for current generate and current measure, the specification for the two modes is identical.  It follows that the range trimming potentiometers may be set using either operating mode.

 

2.1   Error and Stability

Range (FSD)	Error ±%		Temp Coef ppm/oC	Stability typ. ±%/annum
	EXT DVM	INT METER
12x10-3A and 4x10-3A	0.3	1.5	±50	0.1
12x10-4A to 4x10-8A	0.2	1.5	±50	0.1
12x10-9A to 4x10-10A	1.0	2.0	±100	0.1
12x10-11A to 4x10-11A	1.0*	2.0*	±150	0.1
12x10-12A to 12x10-14A	2.0*	3.0*	-1200 typ.	0.5

 

*This does not include the error due to residual current which is less than ±1x10^-14A 
(typically ±2x10^-15A).

 

2.2   Zero Shift

            With temperature:          ±100mV/^oC max

            With input signal:           50mV max (zero to FSD)

            With time:                     ±50mV/hour typical

 

2.3   Residual Current               Less than ±1x10^-14A, typically ±2x10^-15A

 

2.4   Current Generator

Apparent voltage:       Greater than 1kV

Load voltage:              ±3.0V max