HP 4262A User Manual

Section VIII Model 4262A
Paragraphs 8-11 to 8-14
8-11. BASIC THEORY. important functions:first, S1 selects either E1 or
E2 as the voltage to drive the four phase generator
8-12. Figure 8-1 is the basic block diagram of the [this also establishes the measurement mode -either
4262A showing mainly the analog measurement series or parallel which is automatically or manual-
section. It illustrates how the 4262A measures in- ly set (PARA or SER - as selected at the front
ductance L, capacitance C, resistance R and/or dis- panel)] and, secondly, S2 selects either E1 or E2 as
sipation factor D. In this figure, the dotted lines the measurement voltage to charge or discharge the
denote the directions of control signals to and integrator (as appropriate to the measurement
from the nanoprocessor centered control circuit. function and mode - i. e. Cp, Cs, Lp, Ls, Rp or Rs)
A measuring test signal from the oscillator is in the Vector Voltage-Ratio Measurement Section.
applied (at level E1) through the source resistor to
both the unknown device and the range resistor Rr. The Vector Voltage-Ratio Measurement Section
Amplifier Rr causes the same current that flows calculates the measured value for L, C, R or D by
through the unknown device to flow through Rr ascertaining the voltage ratio between E1 and E2
and operates as a current to voltage converter. The through a dual-slope (type) analog to digital con-
effect
of
the
Rr
amplifier
is
to
produce
a
voltage
version
technique.
(This
technique
is
popularly
(E2) equal in phase to and exactly proportional to used in digital voltmeters). The section also pro-
the
current that flows through the unknown device, cesses the E1 and E2 signal flow to make the de-
This amplifier drives the junction of the unknown sired measurement. Selection of either an L, C, R
device and Rr to zero volts (virtual ground); or D measurement and an appropriate equivalent
thus Rr does not affect the unknown device cur- measuring circuit is established by setting detector
rent. The voltage E2 represents the vector current phase reference and by S1 and S2 switch operation
which flows through unknown device at test signal timing. The analog section receives its measure-
level E1. E1 and E2 completely define the electri- ment instructions from the digital section. A de-
cal characteristics of the DUT (Device Under Test) tailed operating description of the Vector Voltage-
at a given test level and frequency. The details of Ratio Measurement Section is given in Paragraph
how the measured values are derived from the ratio 8-15.
of E1 and E2 are discussed in Paragraph 8-16.
8-14. Appropriate values for the source and range
8-13. Voltages E1 and E2, across the unknown resistors, Ro and Rr, are selected with respect to
device and Rr, respectively, are connected to se- the impedance of unknown device. In a series
lector switches S1 and S2. These switches have two equivalent circuit measurement (Ls, Cs or Rs), the
Vector Voltage - Rotio Measurement Section (AI3, Al4 Board)
(A1l Board) (Al2 Board) e thru €a
eref
s
ar
4
Z
/\/\
—%Ge"e"’m—*%ose
phcse]
4
Arnrunr
eref
|(PLL
cxT)
|4f[Generator]
|
Selector
€,€2,€3 0r €4 fe —m___r—i—_
Integrator
r
Phase
Selection/
/
Unknown
\ Device > Signal
~ _ Selection
~
\ N /
oscQ RR Amplifier > oL
\\ \ / Phase !
\
\
\
/
Detector
I
\ ! \ /
\ \ ! \
\ \ \ !
1’ -
oo - —— Mo ~ \ I <
Range Control \ \ ; ~” Integrator Zero Detector
Ro:
Source
Resistor
_\_\
\\
!
.
_COntro|s
-
RR: Range Resistor __ N i _
N pd
Zero Signal
Front Panel Keyboard Nanoprocessor
Keyboard —:> Control Centered Control
Controls le — —
l |
|
i
|
1spiay Control Clock . .
Display Display " Generator Digital Section
(A2, 421, A22,A23 Board)
Figure 8-1. Basic Block Diagram.

HP 4262A Specifications

General

Brand	HP
Model	4262A
Category	Measuring Instruments
Language	English