Tektronix 372, User Manual, Page: 142 / 364

Measurement System
Reference
3Ć30
Measurement Data and Graph Display
Measurement results are stored in memory and immediately displayed on
the graph in the MEASURE menu and on the miniature graph in the CONĆ
FIG menu. Only data that have assigned XĆ and YĆaxis components can be
measured and stored into storage memory.
H X axis:HPUV, HPUI, LPUV, LPUI
H Y axis:HPUV, HPUI, LPUV, LPUI, HPUV and LPUV, HPUI and LPUI.
The maximum number of measurement data points is 4000, in both sweep
and time domain measurement mode.
Curve Analysis
Math feature
The MATH feature allows use of one of four preĆdefined arithmetic equations
to process a displayed curve. These equations are:
H SQRT(HPUI)
H SQRT(LPUI)
H HPUI/LPUI
H Δ HPUI/ Δ LPUV
The HPUI and LPUI parameters in equation 1, 2 and 3 must be the Y axis
components of the displayed curve. The HPUI of equation 4 must be the Y
axis component of the displayed curve, and LPUV must be the X axis comĆ
ponent.
Normally, equation 3 is used to calculate beta (hFE:IC/IB) when HPUI and
LPUI have been selected as a Y axis component, and equation 4 to calcuĆ
late smallĆsignal transconductance gm ( Δ ID/ Δ VGS) when HPUI and LPUV
have been selected as YĆ and XĆaxis components, respectively.
If the parameters of the selected features do not meet these conditions, the
selection causes an error. For example, if the SQRT(LPUI) feature is selected
for an ICĆVCE characteristic curve, the Y axis component is HPUI, so an
error will occur.
If the MATH feature is disabled, the normal display without mathematical
processing is restored because the MATH feature does not update data
stored in memory,
The MATH feature can only operate on data stored in memory, but not
directly on the reference memory. Refer to the following Reference Feature
for a description of processing of reference memory data.