Dual port oscillator for two-stage direct conversion receiver

• US 5,263,197 A
• Filed: 09/20/1991
• Issued: 11/16/1993
• Est. Priority Date: 09/20/1991
• Status: Expired due to Term

• Current Assignee: Matsushita Communication Industrial Corporation of USA (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Communication Industrial Corporation of USA (Panasonic Holdings Corporation)
• Inventors: Manjo, Yoshiharu, McMurray, Charles R., Ohga, Tadashi
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): SOBUTKA, PHILIP
• Application Number:
  US07/762,759
• Time in Patent Office: 788 Days
• Field of Search: 455/324, 455/314, 455/316, 455/317, 455/318, 455/319, 455/320, 455/321, 455/331, 455/333, 331/60, 331/116 R, 331/116 FE, 331/158
• US Class Current: 455/324
• CPC Class Codes: H03B 19/14 by means of a semiconductor device
• CPC Class Codes: H03B 2201/011 the means being an element with a variable capacitance
• CPC Class Codes: H03B 2201/0208 the means being an element with a variable capacitance, e.g. capacitance diode
• CPC Class Codes: H03B 25/00 Simultaneous generation by a free-running oscillator of oscillations having different frequencies
• CPC Class Codes: H03B 5/362 the amplifier being a single transistor H03B5/364 - H03B5/368 take precedence
• CPC Class Codes: H03D 7/16 Multiple-frequency-changing
• CPC Class Codes: H03J 5/0272 the digital values being used to preset a counter or a frequency divider in a phase locked loop, e.g. frequency synthesizer
• CPC Class Codes: H04B 1/28 the receiver comprising at least one semiconductor device having three or more electrodes
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22

Abstract

A two-stage direct conversion receiver. A first mixer (13) converts the incoming signal to an intermediate frequency (IF) signal. A second mixer (16) converts the IF signal to a baseband signal. A detector (17), receiver logic circuit (18), and alerting device circuit (19) act upon the baseband output signal. A two port oscillator (14) provides a fundamental frequency output (FO) and a tripled output frequency (3 FO). The tripled output frequency is again tripled (9 FO) by a frequency multiplier (15) and is provided as a mixing signal to the first mixer (13). The fundamental frequency output is provided to a phase locked loop (20, 21, 22). The output frequency (FV) of the phase locked loop is doubled (2 FV) by a frequency multiplier (23) and provided to a phase shift circuit (24). The output of the phase shift circuit (24) is provided as the second mixing signal to the second mixer (16). The phase locked loop comprises a phase locked loop controller (20), a phase locked loop filter (21), and a voltage controlled oscillator (22). The main oscillator (14) is configured as a crystal controlled Colpitts oscillator, which has an emitter resonant circuit selected to produce oscillation at the fundamental frequency, and a collector resonant circuit selected to extract the third harmonic of the fundamental oscillation frequency. A single active device can therefore provide both the fundamental frequency and the third harmonic frequency. Calibration of the receiver is effected by simply tuning the oscillator (14) to produce a baseband output signal at the output of the second mixer (16). Single step calibration is therefore effected because the voltage controlled oscillator (22) is locked to the main oscillator (14).

Claims

1. An oscillator, comprising:

an amplifying device having an input terminal, a first output terminal, and a second output terminal;

a crystal, having a predetermined characteristic frequency, functionally connected to said input terminal;

a first resonant circuit, having a resonant frequency selected to cause said amplifying device to oscillate only at approximately said predetermined characteristic frequency, and functionally connected to said first output terminal; and

a second resonant circuit, having a resonant frequency being approximately N times said predetermined characteristic frequency, and being functionally connected to said second output terminal, N being an integer greater than one;

wherein said first output terminal primarily provides a first output signal having a frequency approximately the same as said predetermined characteristic frequency, and said second output terminal primarily provides a second output signal having a frequency approximately N times said predetermined characteristic frequency.

2. The oscillator of claim 1 wherein said amplifying device is a transistor.

3. An oscillator, comprising:

an amplifying device having an input terminal, a first output terminal, and a second output terminal, wherein said amplifying device is a transistor having a base for said input terminal, an emitter for said first output terminal, and a collector for said second output terminal;

a crystal, having a predetermined characteristic frequency, functionally connected to said input terminal;

a first resonant circuit, having a resonant frequency selected to cause said amplifying device to oscillate at approximately said predetermined characteristic frequency, and functionally connected to said first output terminal; and

a second resonant circuit, having a resonant frequency being approximately N times said predetermined characteristic frequency, and being functionally connected to said second output terminal, N being an integer greater than one;

wherein said first output terminal provides a first output signal having a frequency approximately the same as said predetermined characteristic frequency, and said second output terminal provides a second output signal having a frequency approximately N times said predetermined characteristic frequency.

4. A direct conversion receiver, comprising:

a first mixer responsive to an input signal and a first mixing signal for providing an intermediate frequency (IF) output signal;

a first oscillator for providing a first oscillator signal to said first mixer as said first mixing signal;

a second mixer responsive to said IF output signal and a second mixing signal for providing a baseband output signal;

a second oscillator for providing a second oscillator signal to said second mixer as said second mixing signal; and

locking means for locking said second oscillator signal in a predetermined relationship to said first oscillator signal.

5. The direct conversion receiver of claim 4 and further comprising:

frequency multiplying means connected between said first oscillator and said first mixer for providing said first mixing signal by multiplying the frequency of said first oscillator signal by M, where M is an integer greater than one.

11. The direct conversion receiver of claim 4 wherein said locking means comprises a phase locked loop controller.

12. The direct conversion receiver of claim 11 wherein said second oscillator comprises a voltage controlled oscillator.

13. The direct conversion receiver of claim 4 and further comprising:

frequency multiplying means connected between said second oscillator and second mixer for providing said second mixing signal by multiplying the frequency of said second oscillator by M, where M is an integer greater than 1.

6. A direct conversion receiver, comprising:

a first mixer responsive to an input signal and a first mixing signal for providing an intermediate frequency (IF) output signal;

a first oscillator for providing a first oscillator signal to said first mixer as said first mixing signal;

a second mixer responsive to said IF output signal and a second mixing signal for providing a baseband output signal;

a second oscillator for providing a second oscillator signal to said second mixer as said second mixing signal; and

locking means for locking said second oscillator signal in a predetermined relationship to said first oscillator signal;

wherein said first oscillator has a first port for providing a reference signal to said locking means and a second port for providing said first oscillator signal.

7. A direct conversion receiver, comprising:

a first mixer responsive to an input signal and a first mixing signal for providing an intermediate frequency (IF) output signal;

a first oscillator for providing a first oscillator signal to said first mixer as said first mixing signal;

a second mixer responsive to said IF output signal and a second mixing signal for providing a baseband output signal;

a second oscillator for providing a second oscillator signal to said second mixer as said second mixing signal; and

locking means for locking said second oscillator signal in a predetermined relationship to said first oscillator signal;

wherein said first oscillator has a first port for providing a reference signal having a first frequency to said locking means, and a second port for providing said first oscillator signal having a frequency of N times said first frequency, where N is an integer greater than 1.

8. The direct conversion receiver of claim 7 wherein said first oscillator comprises:

an amplifying device having an input terminal, a first output terminal, and a second output terminal;

a crystal, having a predetermined characteristic frequency, functionally connected to said input terminal;

a first resonant circuit, having a resonant frequency selected to cause said amplifying device to oscillate at said predetermined characteristic frequency, functionally connected to said first output terminal; and

a second resonant circuit, having a resonant frequency being approximately N times said predetermined characteristic frequency, functionally to said second output terminal, N being an integer greater than one;

wherein said first output terminal functions as said first port and said second output terminal functions as said second port.

9. The direct conversion receiver of claim 8 wherein said amplifying device is a transistor.

10. The direct conversion receiver of claim 9 wherein said transistor has a base for said input terminal, an emitter for said first output terminal, and a collector for said second output terminal.

14. A precision, multifrequency oscillator circuit, comprising:

a crystal;

a first oscillator, functionally connected to said crystal, for providing a first output signal, said first output signal having a first frequency, said first frequency being determined primarily by said crystal;

a second oscillator, responsive to a frequency control signal, for providing a second output signal, said second output signal having a second frequency, said second frequency being determined by said frequency control signal and being a frequency other than an integer multiple or an integer submultiple of said first frequency; and

a controller functionally connected to said first oscillator and said second oscillator for providing said frequency control signal, said frequency control signal being responsive to a relationship between a first scaled signal and a second scaled signal, said first scaled signal having a frequency equal to a first integer submultiple of said first frequency, said second scaled signal having a frequency equal to a second integer submultiple of said second frequency.

15. The oscillator circuit of claim 14 wherein said second oscillator is a voltage controlled oscillator.

16. The oscillator circuit of claim 14 wherein said controller and said second oscillator are embodied in a phase locked loop.

17. The oscillator circuit of claim 14 and further comprising a lowpass filter connected between said controller and said second oscillator for low pass filtering said frequency control signal.

18. The oscillator circuit of claim 14 and further comprising tuning means for precisely setting said first frequency.

19. The oscillator circuit of claim 18 wherein said tuning means comprises a variable capacitor.

20. The oscillator circuit of claim 14 wherein said first oscillator is configured as a Colpitts oscillator.