Superregenerative oscillator RF receiver with differential output

• US 20020168957A1
• Filed: 05/08/2001
• Published: 11/14/2002
• Est. Priority Date: 05/08/2001
• Status: Active Grant

• Current Assignee: Robert Bosch Corporation (Robert Bosch GmbH)
• Original Assignee: Robert Bosch Corporation (Robert Bosch GmbH)
• Inventors: Mapes, Gordon
• Granted Patent: US 6,873,838 B2
• Time in Patent Office: Days
• US Class Current: 455/336
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22

Abstract

A superregenerative oscillator RF receiver is disclosed that has a differential output that has the advantage of providing an improved operating range and increased receiver sensitivity without affecting receiver cost or current requirements. The present invention comprises a receiver that has a super-regenerative oscillator from which the demodulated output is taken in differential form. This is achieved by generating collector and emitter output signals, low pass filtering both signals, and then combining them in a difference amplifier. The resulting waveform contains approximately twice the signal content than would be yielded from a singled-ended circuit. The preferred embodiment of present invention can also achieve quench noise cancellation with proper layout and the use of a common mode low pass filter followed by a difference amplifier.

Claims

1. A superregenerative oscillator for use in a superregenerative receiver, comprising:

a bipolar transistor connected in a tunable circuit to provide a demodulated differential output in response to RF energy being applied thereto, said differential output comprising a collector output and an emitter output, with said collector output being of opposite phase relative to said emitter output.

2. A superregenerative oscillator as defined in claim 1 wherein said oscillator is self-quenching and wherein:

said transistor has a collector, base and emitter, with an input being connected to said collector and to said emitter via a capacitor;

said collector being connected to said collector output via a tunable inductor in parallel with a first capacitor;

said emitter being connected to said emitter output via a second inductor and to said collector via a second capacitor;

said base being connected to said emitter output via a second capacitor and to a source of biasing voltage;

said collector output being connected to said emitter output via a third capacitor.

3. A superregenerative oscillator as defined in claim 1 wherein said oscillator is externally quenched and wherein:

said transistor has a collector, base and emitter, with an input being connected to said collector and to said emitter via a capacitor;

said collector being connected to said collector output via a tunable inductor in parallel with a first capacitor;

said emitter being connected to said emitter output via a second inductor, and to said collector via a second capacitor;

said base being connected to a quench oscillator.

4. A superregenerative oscillator as defined in claim 3 wherein said quench oscillator provides a signal having a duty cycle of approximately 5% and a frequency of approximately 100 kHz.

5. A receiver for generating a demodulated output signal for controlling an operating element in response to detecting a transmitted RF signal, comprising:

an input filter for filtering an RF signal applied thereto;

a superregenerative oscillator comprising a bipolar transistor connected in circuit to produce a collector signal and an emitter signal;

a low pass filter connected to said oscillator for canceling symmetrical quench frequency voltage components of said emitter and collector signals;

an amplifier for combining said collector and emitter signals to produce a single-ended output signal; and

,

a data comparator for demodulating said amplifier output signal and producing a receiver output signal for controlling the operating element.

6. A receiver as defined in claim 5 wherein said low pass filter comprises a cascaded RC low pass filter having common mode reject capability.

7. A receiver as defined in claim 5 wherein said low pass filter comprises an active Sallen-and-key low pass filter.

8. A receiver as defined in claim 5 wherein the operating element comprises an electric motor.

9. A receiver as defined in claim 5 wherein the operating element comprises a solenoid having a member that is moveable in response to the energization of the solenoid.

10. A receiver for generating a demodulated output signal for controlling an operating element in response to detecting a transmitted RF signal, comprising:

an input filter for filtering an RF signal applied thereto;

a superregenerative oscillator comprising a bipolar transistor connected in a tunable circuit to provide a demodulated differential output in response to RF energy being applied thereto, said differential output comprising a collector output and an emitter output, with said collector output being of opposite phase relative to said emitter output;

a low pass filter connected to said oscillator for canceling symmetrical quench frequency voltage components of said emitter and collector outputs;

an amplifier for combining said collector and emitter outputs to produce a single-ended output; and

,

a data comparator for converting said amplifier output from analog to logic-level format and producing a receiver output for controlling the operating element.

11. A receiver as defined in claim 10 wherein said oscillator is self-quenching and wherein:

said transistor has a collector, base and emitter, with an input being connected to said collector and to said emitter via a capacitor;

said collector being connected to said collector output via a tunable inductor in parallel with a first capacitor;

said emitter being connected to said emitter output via a second inductor and to said collector via a second capacitor;

said base being connected to said emitter output via a second capacitor and to a source of biasing voltage;

said collector output being connected to said emitter output via a third capacitor.

12. A receiver as defined in claim 10 wherein said oscillator is externally quenched and wherein:

said transistor has a collector, base and emitter, with an input being connected to said collector and to said emitter via a capacitor;

said collector being connected to said collector output via a tunable inductor in parallel with a first capacitor;

said emitter being connected to said emitter output via a second inductor, and to said collector via a second capacitor;

said base being connected to a quench oscillator.

13. A receiver as defined in claim 10 wherein said low pass filter comprises:

first, second and third resistors connected in series between said collector output and a first input of said differential amplifier;

fourth, fifth and sixth resistors connected in series between said emitter output and a second input of said differential amplifier;

a first capacitor connected in parallel between the connection of said first and second resistor and the connection of said fourth and fifth resistors;

a second capacitor connected in parallel between the connection of said second and third resistor and the connection of said fifth and sixth resistors;

a third capacitor connected in parallel between the connection of said third resistor and said first input and the connection of said sixth resistor and said second input.