SAMPLE AND HOLD CIRCUIT

• US 3,764,921 A
• Filed: 10/27/1972
• Issued: 10/09/1973
• Est. Priority Date: 10/27/1972
• Status: Expired due to Term

• Current Assignee: George Phillip Huard
• Original Assignee: George Phillip Huard
• Inventors: Huard, George Phillip
• Primary Examiner(s): Huckert, John W.
• Assistant Examiner(s): Anagnos, L. N.
• Application Number:
  US05/301,385
• Time in Patent Office: 347 Days
• Field of Search: 307/235R,235A,246,251,297,240 328/126,151,165
• US Class Current: 327/93
• CPC Class Codes: G11C 27/024 using a capacitive memory element G11C27/04 takes precedence

Abstract

A sample and hold circuit, having a gate-operable switching device connected between an input and an output, a storage capacitor for storing signals, and a pulse generator for switching the switching device, is provided with a bias circuit for continuously biasing the switching device to a level immediately below the switching level.

Claims

1. In a sample and hold circuit having an input adapted to be connected to a source of electric signals, an output, storage means connected to said output for storing said electric signals, a gated switching device connected between said input and said storage means for applying said electric signals to said storage means, and pulse generator means connected to a gate of said gated switching device for selectively operating said gated switching device between conducting and non-conducting states, the improvement comprising:

bias means connected to said gate for continuously biasing said gated switching device to a level below the switching level of said gated switching device, said bias means including voltage regulator means comprising a transistor having its base connected to said input to receive said electric signals from said source and its collector connected to a source of power, and voltage drop means connected betweeN the emitter of said transistor and said gate, said voltage regulator means providing a predetermined voltage drop between said input and said gate.

2. Apparatus according to claim 1 further including current regulator means connected to said voltage drop means for dissipating current flowing therethrough.

3. Apparatus according to claim 2 wherein said voltage drop means comprises a zener diode having its cathode connected to said emitter of said transistor and having its anode connected to said current regulator means, a resistor connected in parallel to said zener diode, and tap means connected to a midpoint of said resistor and to said gate.

4. Apparatus according to claim 3 further including a diode connected between said tap means and the junction between said pulse generator and said gate to pass current from said tap means to said junction, and second current regulator means connected to said junction for dissipating current flowing through said last-named diode.

5. Apparatus according to claim 1 wherein said voltage drop means includes a zener diode.

6. Apparatus according to claim 5 wherein said pulse generator means generates pulses having amplitudes approximately equal to said predetermined voltage drop.

7. Apparatus according to claim 1 further including a diode connected between said voltage drop means and the junction between said pulse generator and said gate to pass current from said voltage drop means to said junction, and current regulator means connected to said junction for dissipating current flowing through said diode.

8. Apparatus according to claim 1 wherein said pulse generator means generates pulses having amplitudes approximately equal to said predetermined voltage drop.

9. In a sample and hold circuit having an input adapted to be connected to a source of electric signals, an output, storage means connected to said output for storing said electric signals, a gated switching device connected between said input and said storage means for applying said electric signals to said storage means, and pulse generator means connected to a gate of said gated switching device for selectively operating said gated switching device between conducting and non-conducting states, the improvement comprising:

bias means connected to said gate for continuously biasing said gated switching device to a level below the switching level of said gated switching device, said bias means including voltage regulator means connected to said input to receive electric signals from said source, said voltage regulator means providing a predetermined voltage drop between said input and said gate, and current regulator means connected to said voltage regulator means for dissipating current flowing through said voltage regulator means.

10. Apparatus according to claim 9 further including a diode connected between said voltage regulator means and the junction between said pulse generator means and said gate to pass current from said voltage regulator means to said junction, and second current regulator connected to said junction for dissipating current flowing through said diode.

11. Apparatus according to claim 9 wherein said pulse generator means generates pulses having amplitudes approximately equal to said predetermined voltage drop.