鈥?/div>
HIGH VOLTAGE INSTRUMENTATION
PIEZO TRANSDUCER EXCITATION
PROGRAMMABLE POWER SUPPLIES UP TO 430V
ELECTROSTATIC TRANSDUCERS & DEFLECTION
PATENTED
DESCRIPTION
The PA98 is a high voltage, high power bandwidth MOSFET
operational amplifier designed for output currents up to 200mA.
Output voltages can swing up to
鹵215V
with a dual supply and
up to +440 volts with a single supply. The safe operating area
(SOA) has no second breakdown limitations and can be
observed with all types of loads by choosing an appropriate
current limiting resistor. High accuracy is achieved with a
cascode input circuit configuration. All internal biasing is
referenced to a bootstrapped zener-MOSFET current source.
As a result, the PA98 features an unprecedented supply range
and excellent supply rejection. The MOSFET output stage is
biased on for linear operation. External compensation pro-
vides user flexibility.
This hybrid circuit utilizes thick film (cermet) resistors, ce-
ramic capacitors and silicon semiconductor chips to maximize
reliability, minimize size and give top performance. Ultrasoni-
cally bonded aluminum wires provide reliable interconnec-
tions at all operating temperatures.
TYPICAL APPLICATION
DC
FOCUS
X SWEEP
SAMPLE
z = x
2
+ y
2
Y SWEEP
SAMPLE
R
IN2
PA98
TO
FOCUS
GRID
R
IN1
R
F
+225V
R
CL
鹵225V
DYNAMIC FOCUSING
EQUIVALENT SCHEMATIC
D1
Q1
Q2
Q4
11
+V
S
12
+V
S
D23
COMP
4
5
Q8
Q9
Dynamic focusing is the active correction of focusing volt-
age as a beam traverses the face of a CRT. This is necessary
in high resolution flat face monitors since the distance be-
tween cathode and screen varies as the beam moves from the
center of the screen to the edges. PA98 lends itself well to this
function since it can be connected as a summing amplifier with
inputs from the nominal focus potential and the dynamic
correction. The nominal might be derived from a potentiom-
eter, or perhaps automatic focusing circuitry might be used to
generate this potential. The dynamic correction is generated
from the sweep voltages by calculating the distance of the
beam from the center of the display.
Q12
9
C
L
10
C
L
6
OUT
EXTERNAL CONNECTIONS
1
2
3
NC
Rc
Cc
R
CL
4
5
6
7
8
9
PACKAGE: SIP03
Q6
鈥揑N
1
Q10A
Q7
+IN
2
Q10B
Q17
Q11
10
11
12
Q18
Q13
Q16
D2
8
鈥揤
S
7
鈥揤
S
*
*
鈥揤s
+Vs
鈥揑N
+IN
TO LOAD
AND FEEDBACK
* Bypassing required.
PHASE COMPENSATION
Gain
C
C
1
68pF
20
10pF
100
3.3pF
R
C
100鈩?/div>
330鈩?/div>
0鈩?/div>
C
C
RATED FOR FULL SUPPLY VOLTAGE
APEX MICROTECHNOLOGY CORPORATION
鈥?TELEPHONE (520) 690-8600 鈥?FAX (520) 888-3329 鈥?ORDERS (520) 690-8601 鈥?EMAIL prodlit@apexmicrotech.com
1
1
2
3
4
