Text preview for : Fast fT-Ic Measurement Using the Keysight B2912A 5990-6895EN c20130107 [5].pdf part of Agilent Fast fT-Ic Measurement Using the Keysight B2912A 5990-6895EN c20130107 [5] Agilent Fast fT-Ic Measurement Using the Keysight B2912A 5990-6895EN c20130107 [5].pdf
Back to : Fast fT-Ic Measurement Us | Home
Fast fT-Ic Measurement Using the
Agilent B2900A Series of SMUs
Technical Overview
Agilent B2901/02/11/12A Precision Source/Measure Unit
Agilent B2901A Precision SMU, 1ch, 100 fA resolution, 210 V, 3A DC/10.5 A pulse
Agilent B2902A Precision SMU, 2ch, 100 fA resolution, 210 V, 3A DC/10.5 A pulse
Agilent B2911A Precision SMU, 1ch, 10 fA resolution, 210 V, 3A DC/10.5 A pulse
Agilent B2912A Precision SMU, 2ch, 10 fA resolution, 210 V, 3A DC/10.5 A pulse
Introduction
The cutoff frequency (fT) is an
important parameter to understand
the operating frequency range of a System Configuration through a bias-T (either built-in to
the network analyzer or external) to
bipolar transistor. To measure fT, a Figure 1 shows a system configura- the RF ports of the network analyzer
DC bias must be applied to place the tion to perform fT-Ic measurement and to the DC output terminals of the
transistor at the correct operating using the B2902A or B2912A dual B2900A Series of SMUs.
point while simultaneously using channel SMU in conjunction with a
a network analyzer to measure its network analyzer (such as one from The DC bias voltage or current of the
frequency characteristics. the Agilent ENA or PNA series). B2900A Series of SMUs is applied to
The bipolar transistor is connected the DUT through the bias-T.
The Agilent B2901/02/11/12A
Precision Source/Measure Unit is a
compact and cost-effective bench-top
B2912A
Source/Measure Unit (SMU) that
supplies precise sourcing and mea- Output 1
B2902A or
surement capability at a very reason- Output 2 PC
B2912A
able price. In addition, the B2900A
Series of SMUs supports enhanced External
trigger
trigger functions that enable each
GPIB, LAN or USB
step of a bias sweep it performs to be
synchronized with a frequency sweep Network analyzer
performed by a network analyzer.
Port 1 Port 2
These capabilities allow you to evalu-
Bias-T RF
ate and plot parameters such as fT DC
versus Ic very quickly and efficiently.
Bias-T RF DC +RF
DC
For all of these reasons, the B2900A
DC +RF
Series of SMUs is the ideal bias Transistor
source to use with network analyzers
for the evaluation of transistor DC
and RF characteristics. This technical
overview explains the key features
of the B2900A Series of SMUs in
detail and shows how it can help to Figure 1. System configuration of a fast Ft-Ic measurement system using the
Agilent B2900A Series of SMUs
determine the fT-Ic characteristics of
bipolar transistors.
A PC can control the B2900A Series Figure 2 provides an overview of the measurement using the B2900A
of SMUs and the network analyzer B2900A Series of SMUs. The chan- Series of SMUs and the 11612V
using GPIB, Local Area Network nels of the B2900A Series of SMUs Kelvin bias-T network eliminates the
(LAN) or USB communication proto- support both 2-wire and 4-wire mea- voltage error caused by the residual
cols. In addition, the B2900A Series surements. A 4-wire measurement bias-T resistance.
of SMUs and network analyzer's uses one pair of leads to force current
external trigger inputs and outputs and the other pair of leads to monitor From this discussion it is clear that
are connected to each other, and the (sense) voltage. This eliminates the the B2900A Series of SMUs can be
trigger signals are used to improve voltage measurement error caused used to perform both IV measure-
overall system performance. by residual cable resistance. The ments and to act as a precision bias
B2900A Series of SMUs also supports source in conjunction with a network
a remote-sensing function that keeps analyzer. Conveniently, the B2900A
the voltage applied to the sense point Series of SMUs also supports trigger-
What is the B2900A the same as the programmed voltage. ing functions that allow it to be easily
Series of SMUs? synchronized with other measure-
Agilent offers the 11612V Kelvin ment equipment (such as network
An SMU combines the capabilities
bias-T network to support 4-wire analyzers).
of a current source, a voltage source,
measurement. Performing a 4-wire
a current meter and a voltage meter
along with the capability to switch
easily between these various func-
tions in a single instrument. This
gives it the ability to evaluate the
IV characteristics of devices easily
across all four quadrants without any
additional equipment.
The members of the B2900A Series
of SMUs are single or dual channel
SMU units that offer a wide range of
IV measurement capability for a vari-
ety of two-terminal and three-terminal
Output channel 1
devices. They cover currents from
10 fA to 3 A (DC)/10.5 A (pulse) and a) Front view (for the B2902A and B2912A, the channel 2 is located on the
voltages from 100 nV to 210 V. In rear panel)
addition to their DC operation mode, Sense high Force high
the B2900A Series of SMUs also
has the ability to perform pulsed
measurements in order to prevent
device self-heating from distorting
the measurement results. Guard
Common
Sense low Force low
b) Layout of output terminals
Figure 2. Overview of the B2900A Series of SMUs and its output terminals
2
Measuring f T-Ic To find the maximum cutoff frequency
fT_max, the base current (Ib) is swept
Characteristics while measuring the collector current
The cutoff frequency (fT) can be cal- (Ic). At each step of the Ib sweep,
culated from the H21 parameter, and S-parameters are measured and used
the H parameters can be calculated to calculate the cutoff frequency, fT.
from the measured S parameters.
Figure 3a shows an example of fT Figure 3b shows an example of a
extraction using H parameters. measured fT-Ic curve. The maximum
cutoff frequency, fT_max, can be
The absolute value of H21 at 1 GHz is determined from this curve. In this
calculated, and a line is drawn at this example, the fT_max is 14.9 GHz when
point with a