Dual port oscillator for two-stage direct conversion receiver
First Claim
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.
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Accused Products
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).
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Citations
20 Claims
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1. An oscillator, comprising:
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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. - View Dependent Claims (2)
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3. An oscillator, comprising:
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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.
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4. A direct conversion receiver, comprising:
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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. - View Dependent Claims (5, 11, 12, 13)
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6. A direct conversion receiver, comprising:
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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.
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7. A direct conversion receiver, comprising:
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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. - View Dependent Claims (8, 9, 10)
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14. A precision, multifrequency oscillator circuit, comprising:
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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. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification