Oscillator with bias and buffer circuits formed in a die mounted with distributed elements on ceramic substrate

• US 5,140,286 A
• Filed: 08/02/1991
• Issued: 08/18/1992
• Est. Priority Date: 08/02/1991
• Status: Expired due to Term

• Current Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Black, Gregory R., Hietala, Alexander W., Agahi-Kesheh, Darioush
• Primary Examiner(s): Grimm, Siegfried H.
• Application Number:
  US07/739,573
• Time in Patent Office: 382 Days
• Field of Search: 331/99, 331/108 C, 331/108 D, 331/117 R, 331/117 D, 331/177 V, 331/185, 331/186, 455/75, 455/76, 455/87, 361/395, 361/397, 361/400, 361/406
• US Class Current: 331/99
• CPC Class Codes: H03B 2200/002 making use of ceramic material
• CPC Class Codes: H03B 2200/0022 characterised by the substrate, e.g. material
• CPC Class Codes: H03B 2200/0034 including a buffer amplifier
• CPC Class Codes: H03B 2200/0036 including an emitter or source coupled transistor pair or a long tail pair
• CPC Class Codes: H03B 2200/0062 Bias and operating point
• CPC Class Codes: H03B 2200/0098 having a balanced output signal
• CPC Class Codes: H03B 2201/0208 the means being an element with a variable capacitance, e.g. capacitance diode
• CPC Class Codes: H03B 5/04 Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
• CPC Class Codes: H03B 5/1209 the amplifier having two current paths operating in a differential manner and a current source or degeneration circuit in common to both paths, e.g. a long-tailed pair. H03B5/1215 takes precedence
• CPC Class Codes: H03B 5/1231 the amplifier comprising one or more bipolar transistors
• CPC Class Codes: H03B 5/1243 the means comprising voltage variable capacitance diodes

Abstract

A voltage controlled oscillator and buffer amplifier circuit (211) is disclosed. The circuit is in a stacked configuration, whereby, the current from the power supply (361) is used by the buffer amplifier circuit and reused by the VCO circuit. The VCO circuit includes two transistors (333, 325). The transistors are set-up in a mirrored configuration, so that one of the transistors (325) controls the bias current in the other transistor (333). Both of the transistors are integrated into a semiconductor circuit die (365), thus, matching the thermal characteristics of the transistors (333, 325) and improving control of the bias current. The die (365) is bonded to a ceramic substrate (601). The substrate (601) has connectivity paths for connecting components in the circuit die to components external to the circuit die. Some of the connectivity paths are made of a material and length to form passive circuit elements.

Claims

1. An oscillator for creating a signal having a predetermined frequency of at least 100 MHz, said oscillator comprising:

means for generating the signal at the predetermined frequency including at least a first transistor and a resonant element, said first transistor having a bias current and an emitter, a base and a collector, said emitter having a first predetermined area and coupled to said resonant element; and

means for creating said bias current for said first transistor, said means for creating said bias current including at least a second transistor having an emitter, said emitter having a second predetermined area, wherein said bias current is dependent upon a ratio of said first predetermined area to said second predetermined area.

2. An oscillator in accordance with claim 1 wherein said predetermined frequency is fixed.

3. An oscillator in accordance with claim 1 wherein said predetermined frequency is selectable.

4. An oscillator in accordance with claim 1 further comprising a first resistive element having a first and a second end, said first end of said resistive element coupled to said base of said second transistor, said second end of said resistive element coupled to an electrical ground, wherein said bias current is dependent upon a ratio greater than the ratio of said first predetermined area to said second predetermined area.

5. An oscillator in accordance with claim 1 wherein said oscillator further comprises an integrated circuit die including said first and second transistor and bonding to a ceramic substrate, said ceramic substrate providing connectivity paths from said integrated circuit to at least one external component, said connectivity paths providing at least one inductive and at least one resonant element of the oscillator, whereby said first and said second transistors have matching thermal characteristics.

6. An oscillator in accordance with claim 1 wherein said first and said second transistors are bipolar transistors.

7. An oscillator in accordance with claim 1 wherein said first and said second transistors are NPN type transistors.

8. An oscillator in accordance with claim 1 wherein said first and said second transistors have matching thermal characteristics.

9. An oscillator in accordance with claim 5 wherein said inductive element is coupled to said collector of said first transistor.

10. An oscillator in accordance with claim 5 wherein said inductive element is coupled to said base of said first transistor.

11. A voltage controlled oscillator (VCO) including a power supply, a resonant device, at least a first input signal and a first output signal having a voltage level, the VCO comprising:

a buffer amplifier coupled to and amplifying an output signal of the resonant device creating the first output signal of the VCO, said buffer amplifier deriving power from the power supply and substantially integrated into a circuit die;

the resonant device including at least a first transistor and an inductive element, said first transistor having a bias current, a base, a collector and an emitter, said emitter having a first predetermined area and coupled to said inductive element, said first transistor integrated into said circuit die and deriving power from said buffer amplifier;

means for creating said bias current for said first transistor, said means for creating said bias current including at least a second transistor having an emitter, said emitter having a second predetermined area, wherein said bias current is dependent upon a ratio of said first predetermined area to said second predetermined area and the voltage level of the first input signal, said means for creating said bias current integrated into said circuit die; and

said circuit die coupled to a ceramic substrate, said ceramic substrate providing connectivity paths from said circuit die to at least one external component, said connectivity paths providing at least one inductive and at least one resonant element of the VCO.

12. A voltage controlled oscillator in accordance with claim 11 further comprising a first resistive element having a first and a second end, said first end of said first resistive element coupled to said base of said second transistor, said second end of said first resistive element coupled to an electrical ground, wherein said bias current is dependent upon a ratio greater than the ratio of said first predetermined area to said second predetermined area.

13. A voltage controlled oscillator in accordance with claim 11 wherein said first and said second transistors are bipolar transistors.

14. A voltage controlled oscillator in accordance with claim 11 wherein said first and said second transistors are NPN type transistors.

15. A voltage controlled oscillator in accordance with claim 11 wherein said first and said second transistor have matching thermal characteristics.

16. A radiotelephone including a transceiver, a stable reference source and a phase locked loop (PLL), the radio telephone comprising:

means for generating a first signal at a predetermined frequency greater than 100 MHz, said means for generating coupling to the PLL, the PLL is phase locked to the stable reference source, said means for generating including at least a first transistor having a bias current and a base, a collector and an emitter, said emitter having a first predetermined area and coupled to a first inductive element;

means for creating said bias current for said first transistor, said means for creating said bias current including at least a second transistor having an emitter, said emitter having a second predetermined area, wherein said bias current is dependent upon a ratio of said first predetermined area to said second predetermined area; and

means for transmitting a radio frequency signal having a frequency dependent upon said predetermined frequency of said first signal.

17. A radiotelephone in accordance with claim 16 wherein said means for generating a first signal is substantially integrated into a circuit die, said circuit die including said first and said second transistors and bonding to a ceramic substrate, said ceramic substrate providing connectivity paths from said circuit die to at least the PLL, said connectivity paths providing at least one inductive and at least one resonant element of said means for generating.

18. A radiotelephone in accordance with claim 16 further comprising a first resistive element having a first and a second end, said first end of said first resistive element coupled to said base of said second transistor, said second end of said first resistive element coupled to an electrical ground, wherein said bias current is dependent on a ratio greater than the ratio of said first predetermined area to said second predetermined area.

19. A radiotelephone in accordance with claim 16 wherein said first and said second transistors are bipolar transistors.

20. A radiotelephone in accordance with claim 16 wherein said first and said second transistors are NPN type transistors.

21. A radiotelephone in accordance with claim 16 wherein said first and said second transistors have matching thermal characteristics.

22. A voltage controlled oscillator (VCO) including a power supply, a resonant device, at least a first input signal and a first output signal having a voltage level, the VCO comprising:

a buffer amplifier coupled to and amplifying an output signal of the resonant device creating the first output signal of the VCO, said buffer amplifier deriving power from the power supply and substantially integrated into a circuit die;

the resonant device including at least a first transistor and an inductive element, said first transistor having a bias current, a base, a collector and an emitter, said emitter having a first predetermined area, said inductive element coupled to said collector, said first transistor integrated into said circuit die and deriving power from said buffer amplifier;

means for creating said bias current for said first transistor, said means for creating said bias current including at least a second transistor having an emitter, said emitter having a second predetermined area, wherein said bias current is dependent upon a ratio of said first predetermined area to said second predetermined area and the voltage level of the first input signal, said means for creating said bias current integrated into said circuit die; and

said circuit die coupled to a ceramic substrate, said ceramic substrate providing connectivity paths from said circuit die to at least one external component, said connectivity paths providing at least one inductive and at least one resonant element of the VCO.

23. A voltage controlled oscillator (VCO) including a power supply, a resonant device, at least a first input signal and a first output signal having a voltage level, the VCO comprising:

a buffer amplifier coupled to and amplifying an output signal of the resonant device creating the first output signal of the VCO, said buffer amplifier deriving power from the power supply and substantially integrated into a circuit die;

the resonant device including at least a first transistor and an inductive element, said first transistor having a bias current, a base, a collector and an emitter, said emitter having a first predetermined area, said inductive element coupled to said base, said first transistor integrated into said circuit die and deriving power from said buffer amplifier;

means for creating said bias current for said first transistor, said means for creating said bias current including at least a second transistor having an emitter, said emitter having a second predetermined area, wherein said bias current is dependent upon a ratio of said first predetermined area to said second predetermined area and the voltage level of the first input signal, said means for creating said bias current integrated into said circuit die; and

said circuit die coupled to a ceramic substrate, said ceramic substrate providing connectivity paths from said circuit die to at least one external component, said connectivity paths providing at least one inductive and at least one resonant element of the VCO.

24. In an electrical circuit, an oscillator for generating an oscillating signal of a desired oscillating frequency, said oscillator comprising:

a die formed of a semiconductor material, said die having component circuit elements disposed therewithin, said component circuit elements disposed within the die comprise a first transistor and a second transistor, said first and second transistors having emitters, wherein relative sizes of the emitters of the first and the second transistors define a level of bias current applied to bias the first and second transistors; and

a ceramic substrate bonded to the die and having at least one connectivity path coupled to the die for connecting desired ones of the component elements to desired portions of the electrical circuit, said at least one connectivity path comprised of a material and of a length to form at least one passive circuit element, such that the at least one passive circuit element formed thereby and the component circuit elements disposed within the die together form an oscillating circuit which generates said oscillating signal of the desired oscillating frequency at an output port of the oscillating circuit.

25. The oscillator of claim 24 further comprising an inductor connected between the emitter of the first transistor and a ground plane.