GB2223903A - Local oscillator circuit - Google Patents
Local oscillator circuit Download PDFInfo
- Publication number
- GB2223903A GB2223903A GB8902366A GB8902366A GB2223903A GB 2223903 A GB2223903 A GB 2223903A GB 8902366 A GB8902366 A GB 8902366A GB 8902366 A GB8902366 A GB 8902366A GB 2223903 A GB2223903 A GB 2223903A
- Authority
- GB
- United Kingdom
- Prior art keywords
- circuit
- resonance
- varactor diode
- local oscillating
- fine tuning
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J7/00—Automatic frequency control; Automatic scanning over a band of frequencies
- H03J7/02—Automatic frequency control
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
- H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
- H03B5/1231—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device the amplifier comprising one or more bipolar transistors
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
- H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
- H03B5/1203—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device the amplifier being a single transistor
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
- H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
- H03B5/1237—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device comprising means for varying the frequency of the generator
- H03B5/124—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device comprising means for varying the frequency of the generator the means comprising a voltage dependent capacitance
- H03B5/1243—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device comprising means for varying the frequency of the generator the means comprising a voltage dependent capacitance the means comprising voltage variable capacitance diodes
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B2200/00—Indexing scheme relating to details of oscillators covered by H03B
- H03B2200/003—Circuit elements of oscillators
- H03B2200/004—Circuit elements of oscillators including a variable capacitance, e.g. a varicap, a varactor or a variable capacitance of a diode or transistor
- H03B2200/0042—Circuit elements of oscillators including a variable capacitance, e.g. a varicap, a varactor or a variable capacitance of a diode or transistor the capacitance diode being in the feedback path
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B2201/00—Aspects of oscillators relating to varying the frequency of the oscillations
- H03B2201/02—Varying the frequency of the oscillations by electronic means
- H03B2201/0208—Varying the frequency of the oscillations by electronic means the means being an element with a variable capacitance, e.g. capacitance diode
Abstract
A local oscillating circuit comprises the resonance circuit (3) provided with a resonance varactor diode (D3) for receiving a local oscillating frequency control voltage (VTU) and changing its capacitance value in response to said voltage. An amplifying circuit (1) is connected to the output of the resonance circuit (3). A feedback circuit (2) has a feedback varactor diode (D2) for feeding back the output of said amplifying circuit (1) to said resonance circuit (3). An AFT circuit (4) is provided with the fine tuning varactor diode (D1) which is coupled to the load capacitor (C3) of the amplifying circuit (1), thereby stabilizing the local frequency displacement due to the automatic fine tuning voltage. <IMAGE>
Description
LOCAL OSCILLATING CIRCUITS
The present invention relates to local oscillating circuits.
In accordance with the present invention there is provided a local oscillating circuit comprising:
(a) resonance circuit having a resonance varactor diode for receiving the local oscillating frequency control voltage and controlling the capacitance between the electrodes:
(b) an amplifying circuit for amplifying the output signal of said resonance circuit; and
(c) a feedback varactor diode for controlling the capacitance between the electrodes by said local oscillating frequency control voltage and feeding back the output signal of satd amplifying circuit to said resonance circuit: (d) a fine tunging varactor diode inserted between the output terminal of said amplifying circuit and the ground so as to receive the automatic fine tuning voltage and control the capacitance between the electrodes.
The 21ne tuning varactor diode is coupled to the resonance varactor diode in proportion to the capacitance value of the feedback varactor diode and determines the local oscillating frequency.
Furthermore. 9 this time the capacitance ale of feedback varactor diode is controlled according to the capacitance va'e of the resonance varactor diode. Thus the fine tuning varactor diode is coupled to the resonance varactor diode 7 a ratio in proportion to the capacitance value of the resonance varactor diode.
Local oscillating eircuits embodying the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which :
Fig. 1 is a circuit diagram of a local oscillating circuit embodying the present invention;
Fig. 2 is an equivalent circuit during the oscillating operation of the local oscillating circuit of Fig. 1.
Fig. s is a rap showing the change of the local oscillating frequency versus the automatic fine tuning voltage both for the local oscillating circuit of Figure 1 and for a previously proposed local oscillating circuit: Fig. 4 is a circuit diagram of a previously proposed local oscillating circuit
Fig. 5 is an equivalent circuit during the oscillating operation of previously proposed local oscillating circuit.
The previously proposed local oscillating circuit shown in Fig. 4 includes an amplifying circuit 1, a feedback c rout 2, a resonance circuit 3 and an AFm circuit 4. The amplifying circuit 1 includes an oscillating transistor Tri to which a DC bias A is applied from power voltage source VCC through resistors R4, R5, R6 and R7.A condenser C6 is a ground condenser, which equivalently grounds the base of transistor Tri during the AC oteration. The emitter of transistor
Tri is connected through condenser d to an outtut terminal 21. Also, output terminal 21 has condenser C7 connected as 8 the load thereto, one end of which is grounded. The input terminal of amplifying circuit 1 (the collector of transistor Tri) is couplet through a resonance inductance L@ to a resenance circuit which, as wfll be described hereinafter, amplifies the signal produced at both ends of the inductance
L1, and outputs at output terminal 21.
The feedback circuit 2 includes a varactor diode D2 having an anode coupled to output terminal 21 of the amplifying circuit 1. The anode of varactor diode D2 is grounded through a resistor o. Also its cathode is connected to the node a of the resonance circuit 3. As a result, the output signal of amplifying circuit 1 at the output terminal 21 is fed back through the varactor diode D2 to the resonance circuit 3.
The resonance circuit 3 is coupled to the input terminal of the amplifying circuit 1 as described above. That is to say, the cathode of the resonance varactor diode D3 and one end of the condenser C3 are both connected to the node a. The condenser C2 has one end connected to earth and the other end to the anode of the varactor diode D3. A resistor P3 Is connected in parallel el with the condenser C2. The inductance Li is connected in series with the condenser C5 to ground.The resonance circuit 3 as described above is coupled to the amplifylng circuit 1 by means of the inductance L1 Also, node a of resonance circuit 3 is connected through the resistance P2 to the local oscillating frequency control terminal 11. Thus, the varactor diode 3 receives a DC bias from the local oscillatin frequency control terminal VTU through a resistor R3 so that its capacitance value is controlled.As a result, the local oscillating Qrequenc, is controlled and the tuner, adapted to such a local oscillating circuit, performs the channel selection.
The varactor icie P2 of feecoac. circuit 2 has its cathode connect to the node a of the resonance circuit 3 and receives a DC bias from the local oscillating frequency-control voltage source
VTU through a resistor R2, and thus controls its capacitance value. That is to say, the capacitance value is controlled by the local oscillating frequency control voltage source VTU acting on the to varactor diodes D2 and D3. Whereby it is possible, to make the feedback amount furthermore uniform as well as to stabilize the oscillating.
The AFT circuit 4 is connected in parallel with the resonance circuit 3. That is to say, one end of the condenser Cl is connected to the node a, and the cathode of the fine adjusting varactor diode Dl having its anode grounded is coupled to the other end of the condenser C1 as well as through resistor Pi to fIne tuning control terminal 12. The varactor diode D1 receives automatic fine tuning voltage VAFT aDlied to its cathode through the resistor R1 so that its capacitance value may be controlled.
Briefly, this local oscillating circuit comprises an AFT circuit A connected in parallel with a resonance circuit 3 of the colpitts type oscillating circuit.
Fig. 5 represents the equivalent circuit during the oscillating operation of the circuit omitting the DC Bias resistor and the DC preventing condenser in the local oscillating circuit of Fig. a.
In this circuit, the condenser Cf1 corresponds to the feedback varactor diode D2 of Fig. A, the condenser Cf2 corresponds to the condenser C7, the condenser CTU corresponds to the resonance varactor diode D3, the condenser CAFT corresponds to fine tuning varactor diode D1 of Fig. 4. and the inductance L1 corresponds to the resonance inductance L1 of Fig. 4. According to this equivalent circuit, the local oscillating frequency f of the local oscillating circuit is given by:
This local oscillating circuit oscillates at the local oscillating frequency f, and its oscillating output is supplied through the output terminal 21 to the mixer.In the mixer, the difference between the input signal frequency and the local oscillating frequency is detected. The automatic fine tuning control voltage ThFT is applied to fIne tuning control terminal 12 of the local oscillating circuit in Fig. t in order to make said difference equal to a oredetermined value and thus automatically fine adust the local oscillating frequency.
ecause the fine tuning varactor diode is connected in parallel with the resonance varactor diode, then if the capacitance value of the resonance varactor diode is small, for example, if the local oscIllating frequency i, high, the change in the capacitance value in the fine tuning varactor diode has considerable influence on the oscillating frequency. If, however, the capacitance value of the tuning varactor dioe Is high, for example, because the oscillating frequency is low, the change in the capacitance value of the fine tuning varactor diode has almost no influence on the oscillating frequency.
Thus, , in the band of the losal oscillating circuit there is a large frequency deviation in the displacement of the local escillating frequency in response to the automatic fine tuning voltage.
In the local oscillator circuit shown in rg-. 1 parts similar to those in Fig. 4 are similarly referenced.
This local oscillator circuit is different in that the AFT circuit 4 is connected to output terminal 21 of amplifying circuit 1 as compared to the circuit of Fig. A where the AFT circuit 4 is connected in parallel with the resonance circuit 3.
Fig. 2 represents an equivalent circuit during the oscillating operation of the circuit of Fig. 1 omitting the DC bias resistor and the DC preventing condenser in the local oscillating circuit of Fig. 1. In this circuit, the condensors Cf1
Cf2, CTU, and CAFT and the inductance L1 are similar to those shown in Fig. 5. According to the equivalent circuit, the local oscilating frequency f of this local oscillating circuit is given by the equation:
I will be seen that if the capacitance value CAFT of the fine tuning varactor diode Is changed, the local oscillating frequency is controlled according to the capacitance Cf1 of the feedback varactor diode D2.
FIg.3 is a grapn oQ the fine tuning frequency displacement #f relative to the fine tuning control voltage VAFT both for the local oscillating circuit of Fig. 4 and that of Fig. 4. As can be seen in the local oscillating circuit of the resent inventIon the fine tunIng frequency displacement relative to fine tuning control voltage VAFrn is stab within the low band.
Since the fine tuning varactor dIode of
Fig. 1 is connected to the resonance varactor lode through the feedback varactor diode which controls the capacitance value interlocking the resonance varactor diode, its coupling degree is almost proportional to the capacitance value of the resonance varactor diode. huts, it has the effect that the local oscillating frequency displacement amount is stabilized relative to the automatic tuning voltage over the whole band width of the local oscillating frequency.
Claims (2)
1. A local oscillating circuit comprtsfng a resonance circuit having a resonance-varactor diode
for receiving a local oscillating frequencycontrol voltage to control the capacitance between the
electrodes of the diode, an amplifying circuit for
amplifying the output signal of said resonance circuit, and having a load capacitor in its output, a
feedback varactor diode connected between the output
of the amplifying circuit and the resonance circuit
to modify the capacitance of the resonance circuit
and, a fine tuning varactor diode connected in parallel with the load capacitor of the amplifying circuit and responsive to an automatic fine tuning
voltage to vary the capacitance of the amplifyIng circuit.
2. A local oscillator circuit comprisIng a transistor having an emitter path and a collector
path, the parallel combination of a variable capacItor and inductance connected in the emitter path, the variable capacitor being variable in
response to a local oscillator frequency control voltage, a variable feedback capacitor connected between the emitter and collector of the transistor
to vary the resonant frequency of the parallel
combination In response to the output of the transistor, and a load capacitor connected in the
emitter path of the transistor, the improvement
comprising a variable capacitor connected in parallel wlth the load capacitor, the variable capacitor being
variable in capacitance in response to a fine tuning
control voltae.
A local oscillating circuit substantially
as hereinbefore described with reference to Figs. 1
and 2.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63026856A JP2693959B2 (en) | 1988-02-08 | 1988-02-08 | Local oscillation circuit |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8902366D0 GB8902366D0 (en) | 1989-03-22 |
| GB2223903A true GB2223903A (en) | 1990-04-18 |
| GB2223903B GB2223903B (en) | 1992-01-08 |
Family
ID=12204919
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8902366A Expired - Lifetime GB2223903B (en) | 1988-02-08 | 1989-02-03 | Local oscillating circuits |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP2693959B2 (en) |
| KR (1) | KR910001649B1 (en) |
| GB (1) | GB2223903B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004010571A1 (en) * | 2002-07-18 | 2004-01-29 | Qualcomm, Incorporated | Wideband vco resonant circuit method and apparatus |
| DE102006009467A1 (en) * | 2006-03-01 | 2007-09-06 | Rohde & Schwarz Gmbh & Co. Kg | Oscillator with entrained amplifier |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002087082A1 (en) * | 2001-04-11 | 2002-10-31 | Kyocera Wireless Corporation | Tunable matching circuit |
| JP5027472B2 (en) * | 2005-11-09 | 2012-09-19 | ルネサスエレクトロニクス株式会社 | Oscillator and information device using the same |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4846251A (en) * | 1971-10-14 | 1973-07-02 | ||
| JPS5895419A (en) * | 1981-12-01 | 1983-06-07 | Matsushita Electric Ind Co Ltd | Electronic tuning tuner |
| JPS61151415U (en) * | 1985-03-12 | 1986-09-19 |
-
1988
- 1988-02-08 JP JP63026856A patent/JP2693959B2/en not_active Expired - Fee Related
- 1988-10-12 KR KR1019880013292A patent/KR910001649B1/en not_active IP Right Cessation
-
1989
- 1989-02-03 GB GB8902366A patent/GB2223903B/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004010571A1 (en) * | 2002-07-18 | 2004-01-29 | Qualcomm, Incorporated | Wideband vco resonant circuit method and apparatus |
| US6801097B2 (en) | 2002-07-18 | 2004-10-05 | Qualcomm Incorporated | Wideband VCO resonant circuit method and apparatus |
| DE102006009467A1 (en) * | 2006-03-01 | 2007-09-06 | Rohde & Schwarz Gmbh & Co. Kg | Oscillator with entrained amplifier |
| US8031018B2 (en) | 2006-03-01 | 2011-10-04 | Rohde & Schwarz Gmbh & Co. Kg | Oscillator with coupled amplifier |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01202013A (en) | 1989-08-15 |
| JP2693959B2 (en) | 1997-12-24 |
| GB2223903B (en) | 1992-01-08 |
| KR910001649B1 (en) | 1991-03-16 |
| GB8902366D0 (en) | 1989-03-22 |
| KR890013885A (en) | 1989-09-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20060203 |