Keithley 4200-SCS, Руководство пользователя, Страница: 26 / 335

1-16 Return to Section Topics 4200-900-01 Rev. K / February 2017
Section 1: Getting Started Model 4200-SCS User’s Manual
SENSE terminal
The SENSE terminal is a standard triaxial connector used to apply the preamp SENSE signal to
the DUT in a remote sense application.
• The center pin is SENSE
• The inner shield is GUARD
• The outer shield is circuit COMMON
Nominal internal auto-sense resistance appears between SENSE and FORCE.
NOTE
The SENSE terminal does not need to be connected to the DUT for the preamp to
operate correctly. Remote sensing is automatic. If SENSE is connected to the DUT,
errors due to voltage drops in the FORCE path between the preamp and the DUT will
be eliminated; and, the preamp will sense locally.
PreAmp CONTROL connector
The preamp CONTROL connector connects to the SMU PA CNTRL connector and provides both
power and signal connections from the 4200-SMU or 4210-SMU to the 4200-PA preamp.
Multi-frequency capacitance / voltage unit (CVU)
The Model 4210-CVU
1
is a multi-frequency (1 kHz to 10 MHz) impedance measurement card that
is installed in the 4200-SCS mainframe. The AC test signal (10 mV RMS to 100 mV RMS) can be
DC voltage biased from -30 V to +30 V.
The CVU measures impedance by sourcing an AC voltage across the device under test (DUT),
and then measures the resulting AC current and phase difference. The capacitance and
conductance are derived parameters from the measured impedance and phase.
Model 4210-CVU card
Measurement overview
AC impedance measurement (Z
DUT
) of the device under test (DUT) is performed by sourcing an
AC test voltage across the device and measuring the resulting AC current.
The AC current is measured as shown in Figure 1-12 . The 4210-CVU uses an auto balance bridge
(ABB) technique to achieve accurate impedance measurements. The purpose of the ABB is to
create a virtual ground at the DUT to minimize measurement error. Every CVU measurement is
taken with ABB active. The ABB will always attempt to
lock the low side of the DUT to virtual
ground.
If the ABB fails to lock:
• The measurement is made but may be out of specification.
• The returned data is flagged and colored yellow in the data sheet.
• The graph displays an
ABB Not Locked message.
1. In February 2009, the 4210-CVU replaced the 4200-CVU. The 4210-CVU is identical to the 4200-CVU except that
it extends the frequency range to 1 kHz (1 kHz to 9 kHz in 1 kHz increments).