Random bit stream generator and method

• US 5,239,494 A
• Filed: 10/30/1991
• Issued: 08/24/1993
• Est. Priority Date: 10/30/1991
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Golbeck, Edmund C.
• Primary Examiner(s): Mai, Tan V.
• Application Number:
  US07/785,362
• Time in Patent Office: 664 Days
• Field of Search: 364/602, 364/717, 380/46, 331/78
• US Class Current: 708/3
• CPC Class Codes: H03K 3/84 Generating pulses having a predetermined statistical distribution of a parameter, e.g. random pulse generators
• CPC Class Codes: H04L 9/0662 with particular pseudorandom sequence generator

Abstract

A random bit stream generator and method including a regulated current source for generating a noise signal, an amplifier coupled to the regulated source for producing an amplified noise signal, a filter coupled to the amplifier for averaging the random bit stream and producing a feedback input, a comparator coupled to the amplifier and the filter for receiving the amplified noise signal and the feedback input and producing a digital signal, a flip-flop coupled to the comparator for receiving the digital signal and for producing the random bit stream, and quick start circuitry coupled to the amplifier, the comparator, and the flip flip for ensuring randomness in the random bit stream from generator start up.

Claims

1. A generator for producing a random bit stream comprising:

regulated source means for generating a noise signal;

amplifier means for producing an amplified noise signal from the noise signal, the amplifier means coupled to the regulated source means;

comparator means for receiving the amplified noise signal and a feedback input and producing a comparator output signal, the comparator means coupled to the amplifier means;

flip-flop means for receiving the comparator output signal and for producing a random bit stream, the flip-flop means coupled to the comparator means; and

filter means for averaging the random bit stream and producing the feedback input, the filter means coupled to the amplifier means, to the comparator means, and to the flip-flop means.

2. A generator for producing a random bit stream as claimed in claim 1, wherein the regulated source means comprises a programmable current source.

3. A generator for producing a random bit stream as claimed in claim 2, wherein the programmable current source comprises a current regulator integrated circuit.

4. A generator for producing a random bit stream as claimed in claim 2, wherein the amplifier means comprises a two-stage Norton-type operational amplifier.

5. A generator for producing a random bit stream as claimed in claim 1, wherein the filter means comprises:

first filter means for averaging the random bit stream and producing a first feedback signal, the first filter means coupled to the comparator means, the amplifier means, and the flip-flop means; and

second filter means for averaging a complement of the random bit stream and producing a second feedback signal, the second filter means coupled to the comparator means, the amplifier means, and the flip-flop means.

6. A generator for producing a random bit stream as claimed in claim 5, wherein the first and second filter means each comprise an RC low-pass filter.

7. A generator for producing a random bit stream as claimed in claim 1, wherein the flip-flop means comprises:

clock means for generating a periodic clock pulse;

data flip-flop means for receiving the periodic clock pulse and the comparator output signal and for producing an intermediate random bit stream, the data flip-flop means coupled to the clock means; and

buffer means for receiving the intermediate random bit stream and for producing the random bit stream, the buffer means coupled to the data flip-flop means and to the clock means.

8. A generator for producing a random bit stream immediately upon generator start up, the generator comprising:

regulated source means for generating a noise signal;

amplifier means for producing an amplified noise signal from the noise signal, the amplifier means coupled to the regulated source means;

comparator means for receiving the amplified noise signal and a feedback input and producing a comparator output signal, the comparator means coupled to the amplifier means;

flip-flop means for receiving the comparator output signal and for producing a random bit stream, the flip-flop means coupled to the comparator means;

quick start means for ensuring randomness in the random bit stream from generator start up, the quick start means coupled to the amplifier means, the comparator means, and the flip-flop means; and

filter means for averaging the random bit stream and producing the feedback input, the filter means coupled to the amplifier means, the comparator means, and the flip-flop means.

9. A generator for producing a random bit stream as claimed in claim 8, wherein the regulated source means comprises a programmable current source.

10. A generator for producing a random bit stream as claimed in claim 9, wherein the programmable current source comprises a current regulator integrated circuit.

11. A generator for producing a random bit stream as claimed in claim 9, wherein the amplifier means comprises a two-stage Norton-type operational amplifier.

12. A generator for producing a random bit stream as claimed in claim 8, wherein the filter means comprises:

first filter means for averaging the random bit stream and producing a first feedback signal, the first filter means coupled to the comparator means, the amplifier means, and the flip-flop means; and

second filter means for averaging a complement of the random bit stream and producing a second feedback signal, the second filter means coupled to the comparator means, the amplifier means, and the flip-flop means.

13. A generator for producing a random bit stream as claimed in claim 12, wherein the first and second filter means each comprise an RC low-pass filter.

14. A generator for producing a random bit stream as claimed in claim 12, wherein the flip-flop means comprises:

clock means for generating a periodic clock pulse;

data flip-flop means for receiving the periodic clock pulse and the comparator output signal and for producing an intermediate random bit stream, the data flip-flop means coupled to the clock means; and

buffer means for receiving the intermediate random bit stream and for producing the random bit stream, the buffer means coupled to the data flip-flop means and to the clock means.

15. A generator for producing a random bit stream as claimed in claim 14, wherein the quick start means comprises:

external control means for receiving an external input and producing a control signal; and

analog gate means for electrically shorting the first and second feedback signals in response to the control signal, the analog gate coupled to the external control means, to the first filter means and to the second filter means.

16. A generator for producing a random bit stream as claimed in claim 14, wherein the quick start means comprises:

analog gate means for electrically shorting the first and second feedback signals in response to the control signal, the analog gate means coupled to the external control means, to the first filter means and to the second filter means; and

monostable means for receiving the periodic clock pulse and engaging the analog gate means when the periodic clock pulse is not received, the monostable means coupled to the clock means, and to the analog gate means.

17. A generator for producing a random bit stream as claimed in claim 14, wherein the quick start means comprises:

external control means for receiving an external input and producing a control signal;

first diode means for reducing the first feedback control signal to an average signal in response to the control signal, the first diode means coupled between the first filter means and the external control means; and

second diode means for reducing the second feedback control signal to an average signal in response to the control signal, the second diode means coupled between the second filter means and the external control means.

18. A generator for producing a random bit stream as claimed in claim 14, wherein the quick start means comprises:

first diode means for reducing the first feedback control signal to an average signal in response to the control signal, the first diode means coupled to the first filter means;

second diode means for reducing the second feedback control signal to an average signal in response to the control signal, the second diode means to the second filter means; and

monostable means for engaging the first and second diode means, the monostable means coupled to the first and second diode means.

19. A method for producing a random bit stream in a quick-starting generator comprising the steps of:

generating a noise signal in a regulated source;

producing an amplified noise signal from the noise signal in an amplifier;

producing a feedback signal from a filter;

receiving the amplified noise signal and the feedback input and producing a comparator output signal in a comparator;

receiving the comparator output signal in a flip-flop;

producing a random bit stream from the flip-flop;

ensuring randomness in the random bit stream from generator start up using a quick-start circuit; and

averaging the random bit stream.

20. A method for producing a random bit stream in a quick-starting generator as claimed in claim 19, wherein the step of averaging comprises the steps of:

averaging the random bit stream in a first filter;

producing a first feedback signal from the first filter;

averaging a complement of the random bit stream in a second filter; and

producing a second feedback signal from the second filter means.

21. A method for producing a random bit stream in a quick-starting generator as claimed in claim 19, wherein the step of producing the random bit stream comprises the steps of:

generating a periodic clock pulse in a clock;

receiving the periodic clock pulse and the comparator output signal in a data flip-flop;

producing an intermediate random bit stream from the data flip-flop;

receiving the intermediate random bit stream in a buffer; and

producing the random bit stream from the buffer.

22. A method for producing a random bit stream in a quick-starting generator as claimed in claim 19, wherein the step of ensuring randomness comprises the steps of:

receiving an external input in an external control;

producing a control signal from the external control; and

electrically shorting the first and second feedback signals in response to the control signal using an analog gate.

23. A method for producing a random bit stream in a quick-starting generator as claimed in claim 19, wherein the step of ensuring randomness comprises the steps of:

receiving the periodic clock pulse in a monostable;

engaging an analog gate with the monostable when the periodic clock pulse is not received; and

electrically shorting the first and second feedback signals using the analog gate.

24. A method for producing a random bit stream in a quick-starting generator as claimed in claim 19, wherein the step of ensuring randomness comprises the steps of:

receiving an external input in an external control;

producing a control signal from the external control;

reducing the first feedback control signal to an average signal in response to the control signal in a first diode;

reducing the second feedback control signal to an average signal in response to the control signal in a second diode; and

engaging the first and second diode in response to the control signal.

25. A method for producing a random bit stream in a quick-starting generator as claimed in claim 19, wherein the step of ensuring randomness comprises the steps of:

reducing the first feedback control signal to an average signal in a first diode;

reducing the second feedback control signal to an average signal in a second diode; and

engaging the first and second diode using a monostable device.