OSCILLATOR UTILIZING COMPLEMENTARY TRANSISTORS IN A PUSH-PULL CIRCUIT

• US 3,855,552 A
• Filed: 12/17/1973
• Issued: 12/17/1974
• Est. Priority Date: 12/21/1972
• Status: Expired due to Term

• Current Assignee: Gerhard Thanhaeuser
• Original Assignee: Gerhard Thanhaeuser
• Inventors: Thanhaeuser, Gerhard
• Primary Examiner(s): Kominski, John
• Application Number:
  US05/424,928
• Time in Patent Office: 365 Days
• Field of Search: 331/114,116R,159,168
• US Class Current: 331/116.00R
• CPC Class Codes: H01J 23/22 Connections between resonators, e.g. strapping for connecting resonators of a magnetron
• CPC Class Codes: H03B 1/04 Reducing undesired oscillations, e.g. harmonics
• CPC Class Codes: H03B 2200/0062 Bias and operating point
• CPC Class Codes: H03B 2200/007 Generation of oscillations based on harmonic frequencies, e.g. overtone oscillators
• CPC Class Codes: H03B 2200/0082 Lowering the supply voltage and saving power
• CPC Class Codes: H03B 2200/0098 having a balanced output signal
• CPC Class Codes: H03B 5/36 active element in amplifier being semiconductor device H03B5/323, H03B5/326 , H03B5/38 take precedence
• CPC Class Codes: H03L 3/00 Starting of generators

Abstract

An oscillator constructed using complementary transistors in a push-pull configuration employs means to vary at least one base voltage divider resistor to adjust the working points of the complementary transistors and an additional transistor having its emitter-collector circuit connected between the bases of the complementary transistors, which additional transistor has its conduction controlled by the output signal of the oscillator so that the collector-emitter region thereof is progressively driven toward lower and lower resistance in response to increasing amplitude of oscillation.

Claims

1. An oscillator circuit comprising an oscillatory circuit, first and second complementary transistors connected in a pushpull configuration and each having a base and connected to said oscillatory circuit, and a variable voltage divider connected between said bases for adjusting the working points of said first and second complementary transistors, said variable voltage divider comprising a third transistor including a base connected to said oscillatory circuit and an emitter and a collector connected to respective bases of said first and second complementary transistors and a collector-emitter region driven toward progressively lower and lower resistance in response to increasing amplitude of oscillation.

2. The oscillator of claim 1 wherein said first and second complementary transistors each have a collector connected to a respective pole of an electrical supply and an emitter connected to the emitter of the other complementary transistor, first and second serially connected resistors of equal value connecting said emitters together, the junction of said first and second resistors connected to said oscillatory circuit as a return path.

3. The oscillator of claim 2, wherein said oscillatory circuit comprises an oscillator crystal, first, second and third serially connected capacitors connected in parallel with said crystal, said crystal having a first terminal connected to one pole of the electrical supply and a second terminal connected to said bases of said first and second complementary transistors, and a load resistance connected to the one pole of the electrical supply and across said first capacitor, said return from the junction of said first and second resistors connected to the junction between said second and third capacitors.

4. The oscillator according to claim 3, wherein said load resistance comprises a plurality of serially connected resistors, and a junction of said plurality of resistors serving as an output terminal for picking off the generated oscillation.

5. The oscillator of claim 3, comprising a fourth transistor as a control transistor having an emitter, a base and a collector, said emitter of said fourth transistor connected to the junction between said second and third capacitors, said base of said fourth transistor connected to a terminal of the electrical supply, and said collector of said fourth transistor connected to said base of said third transistor, and a diode connected between said emitter and said base of said fourth transistor and poled in a direction opposite to that of the base-emitter diode of said fourth transistor.

6. The oscillator of claim 1, comprising a plurality of serially connected diodes connected between said bases of said first and second complementary transistors and poled in the forward direction with respect to the polarity of the electrical supply for limiting the operating direct current to a fixed maximum.