Superregenerative mixers and amplifiers

• US 3,883,809 A
• Filed: 12/11/1970
• Issued: 05/13/1975
• Est. Priority Date: 05/11/1967
• Status: Expired due to Term

• Current Assignee: Godfrey T. Coate, Peter Ver Planck
• Original Assignee: Godfrey T. Coate, Peter Ver Planck
• Inventors: Ver Planck, Peter, Coate, Godfrey T.
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US05/097,332
• Time in Patent Office: 1,614 Days
• Field of Search: 325/428,429,430,318,449,350 329/168,170,171 321/60,69R 331/174 330/112,61A,61R,34
• US Class Current: 455/336
• CPC Class Codes: H03D 7/04 having a partially negative resistance characteristic, e.g. tunnel diode

Abstract

A superregenerative circuit wherein a tunnel diode or other active device serves to amplify a radio-frequency input signal and which may serve, also, to mix the input signal with a local oscillation to provide an intermediate-frequency output, the local oscillation being a harmonic of the quench-frequency oscillation applied to the tunnel diode or other active device to produce superregeneration.

Claims

1. A superregenerative mixer comprising, in combination, a resonant circuit having an input to receive a radio-frequency signal and having its resonant frequency substantially at the center frequency of said radio-frequency signal, a tunnel diode electrically connected to the resonant circuit, bias means electrically connected in the mixer circuit for establishing an operating point on the tunnel diode current versus voltage characteristic, quench means electrically connected to said tunnel diode and operable to move the operating point of said tunnel diode between regions of negative and positive incremental conductance at a quench frequency much less than the frequency of said signal to cause oscillations in said resonant circuit periodically to grow and decay at the quench frequency, said radio-frequency signal and high-order harmonics of the quench frequency being amplified and mixed by the tunnel diode to produce a resultant intermediate-frequency signal, and intermediate-frequency circuit means electrically connected to said tunnel diode to separate the intermediate-frequency signal generated in said tunnel diode from other signals and couple the intermediate-frequency signal thereby derived to an output, said quench means being operable to provide a quench frequency one of whose high-order harmonics differs from the radio-frequency signal by the frequency of the intermediate-frequency signal, thereby providing a plurality of quench-frequency high-order harmonics to beat with the plurality of frequency components of the amplified radio-frequency signal to produce said intermediate-frequency.

2. A superregenerative mixer as claimed in claim 1 in which an input filter is connected between said input and said resonant circuit, the bandwidth of said input filter being less than the quench frequency thereby to remove unwanted frequencies from the input signal, said input filter being coupled to the resonant circuit sufficiently weakly to avoid substantially modifying the performance of the resonant circuit.

3. A superregenerative mixer as claimed in claim 2 and in which said input filter and said resonant circuit, in combination, form a double-tuned circuit.

4. A superregenerative mixer as claimed in claim 1 and in which the quench means is a quench-frequency oscillator.

5. A superregenerative mixer as claimed in claim 1 in which the quench means is a source of electrical power in combination with an impedance and the said tunnel diode.

6. A superregenerative mixer as claimed in claim 1 and in which the quench means is controlled in frequency by a source that is coherent in phase with the input signal to effect phase coherence between the input and the output signals.

7. A superregenerative mixer comprising, in combination, a resonant circuit having an input to receive a radio-frequency signal and having its resonant frequency substantially at the center frequency of said radio-frequency signal, an active device electrically connected to the resonant circut, bias means electrically connected in the mixer circuit for establishing an operating point on the current versus voltage characteristic of the active device, quench means electrically connected to the active device and operable to move the operating point of said active device between a region in which oscillations grow and a region in which oscillations decay to cause oscillations in said resonant circuit periodically to grow and decay at a quench frequency, said radio-frequency signal and high-order harmonics of the quench frequency being amplified and mixed by the active device to produce a resultant intermediate-frequency signal, and intermediate-frequency circuit means electrically connected to said active device to separate the intermediate-frequency signal generated in said active device from other signals and couple the intermediate-frequency signal thereby derived to an output, said quench means being operable to provide a quench frequency one of whose high-order harmonics differs from the radio-frequency signal by the frequency of the intermediate-frequency signal, thereby providing a plurality of quench-frequency high-order harmonics to beat with the plurality of frequency components of the amplified radio-frequency signal to produce said intermediate frequency.

8. A superregenerative mixer as claimed in claim 7 in which an input filter is connected between the input and the resonant circuit, the bandwidth of said input filter being less than the quench frequency thereby to remove unwanted frequencies from the input signal, said input filter being coupled to the resonant circuit sufficiently weakly to avoid substantially modifying the performance of the resonant circuit.

9. A superregenerative amplifier comprising, in combination, an input filter to receive a radio-frequency signal, a resonant circuit electrically coupled to the input filter and having its resonant frequency substantially at the center frequency of said radio-frequency signal, an active device electrically connected to the resonant circuit, bias means electrically connected into the amplifier circuit for establishing an operating point on the current versus voltage characteristic of the active device, and quench means electrically connected to the active device and adapted to move the operating point of said active device between a region in which oscillations grow and a region in which oscillations decay to cause oscillations in said resonant circuit periodically to grow and decay at a frequency, the bandwidth of said input filter being less than the quench frequency thereby to exclude unwanted frequencies from the radio-frequency signal and said input fIlter being coupled to the resonant circuit sufficiently weakly to avoid substantially modifying the performance of the resonant circuit.

10. A superregenerative amplifier as claimed in claim 9 and in which said input filter and said resonant circuit, in combination, form a double-tuned circuit.

11. A superregenerative amplifier as claimed in claim 9 and in which the quench means is a quench-frequency oscillator.

12. A superregenerative amplifier as claimed in claim 9 in which the quench means is a source of electrical power in combination with an impedance and the said active device.

13. A superregenerative amplifier as claimed in claim 9 and in which the said active device is a tunnel diode.

14. A superregenerative amplifier as claimed in claim 9 in which the resonant circuit in combination with the active device has a plurality of separate acceptance bands one of which passes a desired-signal band and in which said input filter passes the same desired-signal band.

15. A method of superregeneratively amplifying and changing the freqency of a radio-frequency signal to provide and intermediate-frequency output, that comprises:

introducing the radio-frequency signal as an input to a resonant circuit and an active device electrically connected to the resonant circuit, biasing the active device to establish an operating point on the current versus voltage characteristic thereof, moving the operating point of the active device between a region in which oscillations grow and in which oscillations decay to cause oscillations in said resonant circuit periodically to grow and decay at a quench frequency, adjusting the quench frequency to provide a frequency whose high-order harmonics differ from the frequency components of the amplified radio-frequency signal by the frequency of the intermediate-frequency signal, amplifying said radio-frequency signal and mixing the frequency components of the amplified radio-frequency signal with said high-order harmonics of the quench frequency in the active device to produce a resultant intermediate-frequency signal, separating the intermediate-frequency signal generated in said active device from other signals, and coupling the intermediate-frequency signal thereby derived to an output.

16. A method as claimed in claim 15 that includes providing an input filter between the input to the circuit and the resonant circuit which, in this instance, has an acceptance band in the absence of filtering that separates into several sub-bands spaced by the quench frequency, one of the sub-bands being of appropriate width and location in the spectrum to pass the desired-signal band, adjusting the input filter to pass the same desired-signal band, and coupling the input filter to the resonant circuit sufficiently weakly to avoid substantially modifying the performance of the resonant circuit.

17. A method of superregeneratively amplifying a radio-frequency signal, that comprises:

introducing the radio-frequency signal to a resonant circuit and an active device, electrically connected to the resonant circuit, through an input filter;

biasing the active device to establish an operating point on the current versus voltage characteristic thereof;

moving the operating point of the active device between a region in which oscillations grow and a region in which oscillations decay to cause oscillations in said resonant circuit periodically to grow and decay at a quench frequency;

adjusting the resonant circuit and the growth and decay of oscillations so that the resonant circuit has an acceptance band, in the absence of filtering, that separates into several sub-bands spaced by the quench frequency;

one of the sub-bands being of appropriate width and location in the spectrum to pass the desired-signal band;

adjusting the input filter to pass the same desired-signal band; and

coupling the input filter to the resonant circuit sufficiently weakly to avoid modifying the performance of the resonant circuit.