US4134085A — Narrow deviation voltage controlled crystal oscil…

Claim 1

Independent Claim 172 words

In a voltage controlled crystal oscillator (VCXO) for providing an output signal of a frequency in accordance with a control voltage applied thereto, said VCXO being of the type including a composite resonator coupled to a negative resistance generator, said composite resonator comprising a crystal, in series connection with a parallel combination of a voltage variable capacitance device, responsive to a control voltage applied thereto, and an inductance; said crystal having a unit static capacitance associated therewith and said voltage variable capacitance having a predetermined reactance versus voltage characteristic, the improvement wherein: said inductance is of a predetermined value equal to the parallel combination of (a) a first inductance exhibiting a reactance complementary to the reactance of said unit static capacitance and (b) a second inductance exhibiting a reactance to provide, when in effective parallel connection across said voltage variable capacitance, an inflection point in the reactance versus voltage characteristic of the parallel combination of said second inductance and said voltage variable capacitance at a nominal mid-band value of said control voltage.

Claim 2

Dependent Claim 172 words

In a voltage controlled crystal oscillator (VCXO) for providing an output signal of a frequency in accordance with a control voltage applied thereto, said VCXO being of the type including a composite resonator coupled to a negative resistance generator, said composite resonator comprising a crystal, in series connection with a parallel combination of a voltage variable capacitance device, responsive to a control voltage applied thereto, and an inductance; said crystal having a unit static capacitance associated therewith and said voltage variable capacitance having a predetermined reactance versus voltage characteristic, the improvement wherein: said inductance is of a predetermined value equal to the parallel combination of (a) a first inductance exhibiting a reactance complementary to the reactance of said unit static capacitance and (b) a second inductance exhibiting a reactance to provide, when in effective parallel connection across said voltage variable capacitance, an inflection point in the reactance versus voltage characteristic of the parallel combination of said second inductance and said voltage variable capacitance at a nominal mid-band value of said control voltage.

Claim 3

Dependent Claim 64 words

The VCXO of claim 1 further comprising a resistor shunted across said crystal, said resistor having a value much greater than the reactance of said crystal at the desired nominal VCXO operation frequency to provide at spurious resonant frequencies an equivalent resonator resistance greater than the magnitude of the negative resistance provided by said generator at said spurious resonant frequency and thereby prevent oscillation.

Claim 4

Dependent Claim 24 words

The VCXO of claim 2 further comprising: a variable capacitance, connected in series with said resonator, for adjusting the center frequency of said VCXO.

Claim 5

Dependent Claim 24 words

The VCXO of claim 1 further comprising: a variable capacitance, connected in series with said resonator, for adjusting the center frequency of said VCXO.

Claim 6

Dependent Claim 134 words

The VCXO of claim 1 wherein: said crystal has a motional inductance of value L 1 , motional capacitance of value C 1 , static capacitance of value C 0 , and series resonant frequency ω s , said voltage variable capacitance is an abrupt junction varactor with a contact potential φ and four volt capacitance C -4 , and said inductor has a value L L , where: L.sub.L = [(1/ω.sub.s.sup.2 C.sub.0) (3/ω.sup.2 C.sub.-4) ((V.sub.0 + φ)/(4 + φ)).sup.1/2 ]/[(1/ω.sub.s.sup.2 C.sub.0) + (3/ω.sup.2 C.sub.-4) ((V.sub.0 + φ)/(4 + φ)).sup.1/2 ] and C.sub.-4 = (-9/16K.sub.0) (1/ω.sub.s L.sub.1) ((V.sub.0 + φ) (4 + φ)).sup.-1/2 where K 0 is the sensitivity of said VCXO and V 0 is a bias voltage applied to said varactor and ω is the nominal frequency of operation of said VCXO.

Claim 7

Dependent Claim 133 words

The VCXO of claim 3 wherein: said crystal has a motional inductance of value L 1 , motional capacitance of value C 1 , static capacitance of value C 0 , and series resonant frequency ω s , said voltage variable capacitance is an abrupt junction varactor with a contact potential φ and four volt capacitance C -4 , and said inductor has a value L L where: L.sub.L = [(1/ω.sub.s.sup.2 C.sub.0) (3/ω.sup.2 C.sub.-4) ((V.sub.0 + φ)/(4 + φ)).sup.1/2 ]/[(1/ω.sub.s.sup.2 C.sub.0) + (3/ω.sup.2 C.sub.-4) ((V.sub.0 + φ)/(4 + φ)).sup.1/2 ] and C.sub.-4 = (-9/16K.sub.0) (1/ω.sub.s L.sub.1) ((V.sub.0 + φ) (4 + φ)).sup.-1/2 wherein K 0 is the sensitivity of said VCXO and V 0 is a bias voltage applied to said varactor and ω is the nominal frequency of operation of said VCXO.

Claim 8

Dependent Claim 185 words

In a voltage controlled crystal oscillator (VCXO) of the type including a resonator coupled to a negative resistance generator, said resonator comprising a crystal, a voltage variable capacitance device, a linearization inductance, the improvement wherein: said variable capacitance device is coupled in series with said crystal and said inductance is effectively an inductor coupled across said variable capacitance device; said crystal having a motional inductance of L 1 , motional capacitance of value C 1 , static capacitance of value C 0 and series resonant frequency ω s , said voltage variable capacitance being an abrupt junction varactor with a contact potential φ and four volt capacitance C -4 , and said inductor has a value of L L where: L.sub.L = [(1/ω.sub.s.sup.2 C.sub.0) (3/ω.sup.2 C.sub.-4) ((V.sub.0 + φ)/(4 + φ)).sup.1/2 ]/[(1/ω.sub.s.sup.2 C.sub.0) + (3/ω.sup.2 C.sub.-4) ((V.sub.0 + φ)/(4 + φ)).sup.1/2 ] and C.sub.-4 = (-9/16K.sub.0) (1/ω.sub.s L.sub.1) ((V.sub.0 + φ) (4 + φ)).sup.-1/2 wherein K 0 is the sensitivity of said VCXO and V 0 is a bias voltage applied to said varactor and ω is the nominal frequency of operation of said VCXO.

Claim 9

Dependent Claim 185 words

In a voltage controlled crystal oscillator (VCXO) of the type including a resonator coupled to a negative resistance generator, said resonator comprising a crystal, a voltage variable capacitance device, a linearization inductance, the improvement wherein: said variable capacitance device is coupled in series with said crystal and said inductance is effectively an inductor coupled across said variable capacitance device; said crystal having a motional inductance of L 1 , motional capacitance of value C 1 , static capacitance of value C 0 and series resonant frequency ω s , said voltage variable capacitance being an abrupt junction varactor with a contact potential φ and four volt capacitance C -4 , and said inductor has a value of L L where: L.sub.L = [(1/ω.sub.s.sup.2 C.sub.0) (3/ω.sup.2 C.sub.-4) ((V.sub.0 + φ)/(4 + φ)).sup.1/2 ]/[(1/ω.sub.s.sup.2 C.sub.0) + (3/ω.sup.2 C.sub.-4) ((V.sub.0 + φ)/(4 + φ)).sup.1/2 ] and C.sub.-4 = (-9/16K.sub.0) (1/ω.sub.s L.sub.1) ((V.sub.0 + φ) (4 + φ)).sup.-1/2 wherein K 0 is the sensitivity of said VCXO and V 0 is a bias voltage applied to said varactor and ω is the nominal frequency of operation of said VCXO.

Claim 10

Dependent Claim 21 words

The VCXO of claim 1 wherein said negative resistance generator provides a resistance the magnitude of which increases with increasing frequency.

Claim 11

Dependent Claim 21 words

The VCXO of claim 7 wherein said negative resistance generator provides a resistance the magnitude of which increases with increasing frequency.

Claim 12

Dependent Claim 133 words

In the VCXO of claim 1 the further improvement wherein: said negative resistance generator comprises: a voltage dependent current source, having first, second and third terminals, for generating a current at said third terminal having a magnitude in accordance with the voltage between said first and second terminals and having a transconductance gm; first and second capacitances C 1 and C 2 respectively connected in series and coupled between said first and third terminals; and a feedback resistance R E coupled between said second terminal and the juncture between said first and second capacitances; the input impedance of said negative resistance generator appearing across said capacitors and being in accordance with: -j[1/ωC.sub.1 + 1/ωC.sub.2] - [ 1/ω.sup.2 C.sub.1 C.sub.2 (R.sub.E + (1/gm) )] where ω is the frequency of signals from said resonator.

Claim 13

Dependent Claim 13 words

The VCXO of claim 10 wherein R E is much larger than 1/gm.

Claim 14

Dependent Claim 134 words

In the VCXO of claim 7, the further improvement wherein: said negative resistance generator comprises: a voltage dependent current source, having first, second and third terminals, for generating a current at said third terminal having a magnitude in accordance with the voltage between said first and second terminals and having a transconductance gm; first and second capacitances C 1 and C 2 respectively connected in series and coupled between said first and third terminals; and a feedback resistance R E coupled between said second terminal and the juncture between said first and second capacitances; the input impedance of said negative resistance generator appearing across said capacitors and being in accordance with: -j[1/ωC.sub.1 + 1/ωC.sub.2 ] - [1/ω.sup.2 C.sub.1 C.sub.2 (R.sub.E + (1/gm) ) ] where ω is the frequency of signals from said resonator.

Claim 15

Dependent Claim 13 words

The VCXO of claim 12 wherein R E is much larger than 1/gm.

Claim 16

Dependent Claim 103 words

A voltage controlled crystal oscillator (VCXO) comprising: a resonator including a crystal coupled to a voltage variable capacitance device, and a linearization inductance, said resonator having an effective series resistance; p1 a negative resistance generator, responsive to signals from said resonator, for sustaining oscillation when the magnitude of said negative resistance is greater than the effective series resistance of said resonator; and means, cooperating with said resonator, for selectively increasing said effective series resistance to a value greater than said negative resistance magnitude at frequencies outside of a predetermined range of frequencies, to prevent thereby oscillation at spurious resonant frequencies of said resonator.

Claim 17

Dependent Claim 103 words

A voltage controlled crystal oscillator (VCXO) comprising: a resonator including a crystal coupled to a voltage variable capacitance device, and a linearization inductance, said resonator having an effective series resistance; p1 a negative resistance generator, responsive to signals from said resonator, for sustaining oscillation when the magnitude of said negative resistance is greater than the effective series resistance of said resonator; and means, cooperating with said resonator, for selectively increasing said effective series resistance to a value greater than said negative resistance magnitude at frequencies outside of a predetermined range of frequencies, to prevent thereby oscillation at spurious resonant frequencies of said resonator.

Claim 18

Dependent Claim 72 words

The VCXO of claim 14 wherein said negative resistance generator has a relatively high output impedance, and the effective series resistance of said resonator is much less than said negative resistance magnitude in the operational frequency range of said VCXO: further comprising a relatively low input impedance buffer amplifier, receptive of signals from said negative resistance generator, including filter means for extracting a predetermined harmonic of said negative resistance generator output signal.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1982-01-08	1982-07-10	1983-01-09	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1986-01-08	1986-07-10	1987-01-09	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1990-01-08	1990-07-10	1991-01-09	$7700.00	Window Closed / Lapsed

Narrow deviation voltage controlled crystal oscillator for mobile radio

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag