HP 5300A - Field Effect Transistor (FET); Light Emitting Diodes; Integrated Circuit Operation; Overall Operation

Model 5300A
Theory of Operation
4-7. INVERSION. AND and OR gates are shown in
Figure 4-2 (A,B). The circle on the output of a logic
symbol indicates a LOW when activated, as shown in
Figure 4-2(C,D). Thus, a circle indicates inver-
sion. An AND gate with an inverted output is called
a NAND gate; an OR gate with an inverted output is
called a NOR gate. The unit gain amplifier with an
inverted output is called an inverter, Figure 4-2 (F).
4-8. FIELD EFFECT TRANSISTOR (FET)
4-9. Field effect transistors have three terminals:
source, drain, and gate which correspond in function
to emitter, collector, and base of junction transistors.
Source and drain leads are attached tothe sameblock
(channel) of N or P semiconductor material. A band
of oppositely doped material around the channel (be-
tween the source and drain leads) is connected to the
gate lead.
4-10. In normal FET operation, the gate-source volt-
age reverse-biases the PN junction, causing an elec-
tric field that creates a depletion regioninthe source-
drain channel. In the depletion region the number of
available current carriers is reducedas the reverse-
biasing voltage increases, making source-drain cur-
rent a function of gate-source voltage. With the input
(gate-source) circuit reverse-biased, the FET pre-
sents a high impedance to its signal sources (as com-
pared with the low impedance of the forward-biased
junction transistor base-emitter circuit), Because
there is no input current, FET's have less noise than
junction transistors. Figure 4-3 shows the schematic
symbol and biasing for N channel and P channel field
effect transistors.
4-11. LIGHT EMITTING DIODES
4-12. A light emitting diode (LED) is a p-n junction
device which is designed to emit visible radiation
(light) when its p-n junction is forward biased.
4-13. The type of diodes used in the 5300A Display
are Gallium Arsenide Phosphide LED's which emit
radiation in the red region (6400 Angstroms). The
addition of the red front-panel filter enhances the visi-
bility of emitted radiation. Additional subject infor-
mation is available from the HP Journal, July 1970,
and HP Applications Note 931.
4-14. INTEGRATED CIRCUIT OPERATION
4-15. The operation of integrated circuits Al1U1,
A1U2, A1U3, A1U4, and A1U5 is found in paragraphs
4-30 through 4-40. ‘
4-16. OVERALL OPERATION
4-17. Figure 4-4 is an overall block diagram of the
5300A Measuring System and a typical plug-on(5301A
Plug-On). The 5300A Measuring System mainframe
contains the major counting, timing, and display cir-
cuitry which is the basis of ali measurements in the
5300A Measuring System.
4-2
Figure 4-3. Field Effect Transistor Operation
A. FET Amplifier Characteristics
+V
Dp Re
G
aoe
s
CHARACTERISTIC COMMON SOURCE COMMON DRAIN
(Source Follower }
input Impedance IMQ-1SMQ IMQ-ISMQ
Output Impedance S0KN-100KN. {KQ-IOKQ
Voltage Gain 10-200 <t
Power Gain 60dB-100dB 40dB-80dB
B. FET Biasing
TYPE
poe
ee
sel
N-CHANNEL
DRAIN
MAXIMUM
18]
CONTROL | CURRENT CONTROL CURRENT
VOLTAGE FLOW VOLTAGE FLOW
P-CHANNEL
ORAIN
Oo MAXIMUM =| INCREASING | DECREASES
CONTROL } CURRENT CONTROL
VOLTAGE FLOW VOLTAGE
4-18. The functional modules of the mainframe are
shown in Figure 4-4 simplified block diagram. These
are:
a. Display A1A1DS7. A six-digit scanned solid-
state LED display.
b. Scanner (A1U1). A self-contained scanning cir-
cuit which drives the vertical columns of the display
and provides an address code used to identify the dis-
played digit.
c. Character Generator (A1U2). A decoding and
driving circuit which converts the four-line data code
to a 10-line pattern used to drive the horizontal lines |
of the display matrix.
d. Counter (A1U3). A six-digit, 10 MHz counting
and storage register.