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Bias Stabilized High Voltage Amplifier

IP.com Disclosure Number: IPCOM000050055D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Le, T: AUTHOR [+2]

Abstract

This circuit receives a low amplitude ramp input waveform and produces a high voltage parabolic waveform at V3 for cathode ray tube (CRT) dynamic focusing. This is accomplished by an integrator stage which integrates the ramp into a second order parabolic waveform and a high gain stage which amplifies the parabola to a substantially higher voltage.

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Bias Stabilized High Voltage Amplifier

This circuit receives a low amplitude ramp input waveform and produces a high voltage parabolic waveform at V3 for cathode ray tube (CRT) dynamic focusing. This is accomplished by an integrator stage which integrates the ramp into a second order parabolic waveform and a high gain stage which amplifies the parabola to a substantially higher voltage.

Considering the DC operation of the circuit, since the negative input to amplifier A1 is capacitively coupled through capacitor C1, the DC gain of A1 is unity. Therefore, the voltage is equal at all three A1 terminals, and, if resistor R1 equals resistor R2, this voltage is approximately one-half the sum of VCC plus the VD1 voltage across diode D1. D1 is forward biased in the region of the steep I-V slope such that VD1 remains stable with changes in forward current. If the resistance of R3 is substantially greater than that of R2, the voltage V2 at the cathode of D1 is approximately equal to one-half the difference of VCC minus VD1. The V1 output voltage of A1 and V2 are supplied as inputs to amplifier A2.

The DC output V3 of the A2, Q1 amplifier is approximately K(V1-V2) V2, where K is equal to the resistance of R4 divided by the sum of the resistances of R3 and R2. If R3 is substantially greater than R2, then K is equal to R4 divided by R3. Since V1 minus V2 equals VD1, V3 is approximately equal to KVD1 plus V2. Since KVD1 is much greater than V2, the DC output voltage is primar...