Reverse flow neuron

• US 5,065,040 A
• Filed: 08/03/1990
• Issued: 11/12/1991
• Est. Priority Date: 08/03/1990
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Leivian, Robert H., Peterson, William M., Garrison, Sidney C. III
• Primary Examiner(s): HUDSPETH, DAVID R
• Application Number:
  US07/562,169
• Time in Patent Office: 466 Days
• Field of Search: 307/201, 307/242, 307/353, 307/243, 364/513, 364/807, 364/822
• US Class Current: 326/35
• CPC Class Codes: G06N 3/063 using electronic means
• CPC Class Codes: G06N 3/065 Analogue means

Abstract

A neural network is provided for performing bi-directional signal transformations through a matrix of synapses by alternately sending and receiving signal vectors therethrough via switchable driver circuits. In the forward direction, the input signal is transformed according to the weighting elements of the synapses for providing an output signal. The drive direction of the switchable driver circuits may be reversed allowing the output signal to flow back through the same synapses thereby performing a reverse transformation, which may actually be an improved estimate of the original input signal. Sample and hold circuits are provided for latching the output signals of the switchable driver circuits back to the inputs thereof for repeated forward and reverse signal transformations until an acceptable transformation of the original input signal is realized, thereby achieving an improved estimate of the input signal and corresponding output transformation. More generally, a first input signal may be transformed in one direction through the synapses, while a second input signal, possibly independent and unrelated to the first input signal, may be reverse transformed in the opposite direction using the same synapses as the first direction.

Claims

1. A network having a first plurality of inputs coupled for receiving a spatial vector of an input signal for providing a transformation thereof at a first plurality of outputs, comprising:

first and second plurality of conductors;

a plurality of weighting elements interconnected between said first plurality of conductors and said second plurality of conductors in a predetermined manner;

a first plurality of switchable driver circuits respectively coupled between the first plurality of inputs and said first plurality of conductors, said first plurality of switchable driver circuits operating to drive said first plurality of conductors at the occurrence of a first state of a first switch control signal while receiving signals from said first plurality of conductors at the occurrence of a second state of said first switch control signal, said first plurality of switchable driver circuits including first, second and third terminals, said first terminal being coupled to one of the first plurality of inputs, said second terminal being coupled to one of said first plurality of conductors, said third terminal providing one of a first plurality of output signals;

a second plurality of switchable driver circuits respectively coupled between the first plurality of outputs and said second plurality of conductors, said second plurality of switchable driver circuits operating to receive signals from said second plurality of conductors at the occurrence of a first state of a second switch control signal while driving said second plurality of conductors at the occurrence of a second state of said second switch control signal; and

a switch control circuit coupled to said first and second plurality of switchable driver circuits for providing said first and second switch control signals to control the driving direction thereof.

2. The network of claim 1 wherein each of said second plurality of switchable driver circuits include first, second and third terminals, said first terminal being coupled to one of the first plurality of outputs, said second terminal being coupled to one of said second plurality of conductors, said third terminal providing one of a second plurality of output signals.

3. The network of claim 2 further including:

a second plurality of outputs; and

first means coupled between the first plurality of inputs and said second plurality of outputs and said first and third terminals of said first plurality of switchable driver circuits for sampling and holding said first plurality of output signals provided at said third terminals of said first plurality of switchable driver circuits for application to said first terminals of said first plurality of switchable driver circuits.

4. The network of claim 3 further including:

a second plurality of inputs; and

second means coupled between the first plurality of outputs and said second plurality of inputs and said first and third terminals of said second plurality of switchable driver circuits for sampling and holding said second plurality of output signals provided at said third terminals of said second plurality of switchable driver circuits for application to said first terminals of said second plurality of switchable driver circuits.

5. The network of claim 4 wherein one of said first plurality of switchable driver circuits includes:

an amplifier having first and second inputs and having an output, said first input being coupled to said third terminal of said one of said first plurality of switchable driver circuits;

a first switching circuit having first, second and third terminals and a control input, said first terminal being coupled to said one of said first plurality of inputs, said second terminal being coupled to said one of said first plurality of conductors, said third terminal being coupled to said second input of said amplifier, said control input being coupled for receiving said first switch control signal from said switch control circuit, said first and third terminals being coupled together at the occurrence of said first state of said first switch control signal while said second and third terminals are coupled together at the occurrence of said second state of said first switch control signal; and

a second switching circuit having first and second terminals and a control input coupled for receiving said first switch control signal from said switch control circuit, said first terminal being coupled to said output of said amplifier, said second terminal being coupled to said one of said first plurality of conductors, said first and second terminals being coupled together at the occurrence of said first state of said first switch control signal while said first and second terminals are isolated at the occurrence of said second state of said first switch control signal.

6. The network of claim 4 wherein one of said first plurality of switchable driver circuits includes:

an amplifier having first and second inputs and having an output, said first input being coupled to said third terminal of said one of said first plurality of switchable driver circuits;

a first switching circuit having first, second and third terminals and a control input, said first terminal being coupled to said one of said first plurality of inputs, said second terminal being coupled to said one of said first plurality of conductors, said third terminal being coupled to said second input of said amplifier, said control input being coupled for receiving said first switch control signal from said switch control circuit, said first and third terminals being coupled together at the occurrence of said first state of said first switch control signal while said second and third terminals are coupled together at the occurrence of said second state of said first switch control signal; and

a resistor coupled between said output of said amplifier and said one of said first plurality of conductors.

7. A method of performing bi-directional signal transformations through a network of weighting elements, comprising the steps of:

enabling a first plurality of switchable drive circuits for receiving a first input signal;

driving said first input signal from the outputs of said first plurality of switchable drive circuits in a first direction for transforming said first input signal through the synapses of the network;

enabling a second plurality of switchable drive circuits for receiving said transformed first input signal and providing said first output signal;

switching said second plurality of switchable drive circuits for driving a second input signal in a second direction toward said first plurality of switchable driver circuits for performing a transformation thereof by reversing the drive direction through the weighting elements of the network; and

switching said first plurality of switchable drive circuits for receiving said transformed second input signal and providing a second output signal.

8. A network having a plurality of inputs coupled for receiving a spatial vector of an input signal for providing a transformation thereof at a plurality of outputs, comprising:

a first plurality of conductors;

a second plurality of conductors;

a plurality of weighting elements interconnected between said first plurality of conductors and said second plurality of conductors in a predetermined manner;

first means coupled between the plurality of inputs and said first plurality of conductors for driving signals in either direction in response to a first control signal, said first means driving said first plurality of conductors at the occurrence of a first state of said first control signal while receiving signals from said first plurality of conductors at the occurrence of a second state of said first control signal; and

second means coupled between the plurality of outputs and said second plurality of conductors for driving signals in either direction in response to a second control signal, said second means receiving signals from said second plurality of conductors at the occurrence of said first state of said second control signal while driving said second plurality of conductors at the occurrence of said second state of said second control signal.

9. The network of claim 8 further including third means coupled to said first and second means for providing said first and second control signals for controlling the driving direction thereof.

10. The network of claim 9 wherein said first means includes a switchable driver circuit having first and second terminals, said first terminal being coupled to one of the plurality of inputs, said second terminal being coupled to one of said first plurality of conductors.

11. The network of claim 10 wherein said switchable driver circuits includes:

an amplifier having first and second inputs and having an output, said first input being coupled to said third terminal of said switchable driver circuits;

a first switching circuit having first, second and third terminals and a control input, said first terminal being coupled to said one of said first plurality of inputs, said second terminal being coupled to said one of said first plurality of conductors, said third terminal being coupled to said second input of said amplifier, said control input being coupled for receiving said first control signal from said switch control circuit, said first and third terminals being coupled together at the occurrence of said first state of said first control signal while said second and third terminals are coupled together at the occurrence of said second state of said first control signal; and

a resistor coupled between said output of said amplifier and said one of said first plurality of conductors.

12. A bi-directional neuron responsive to a spatial vector of an input signal for providing a transformation thereof at an output, comprising:

a plurality of weighting elements each having an input and an output;

first means coupled between said outputs of said plurality of weighting elements and the output of the bi-directional neuron in a predetermined manner for combining the spatial vector of the input signals at an output; and

a switching circuit having first, second, third, fourth and fifth terminals and having a control input, said first terminal being coupled for receiving one element of the spatial vector of the input signal, said second terminal being coupled to said input of one of said plurality of weighting elements, said third terminal being coupled to said output of said one of said plurality of weighting elements, said fourth and fifth terminals being coupled together to said output of said first means, said first and second terminals and said third and fifth terminals being coupled together at the occurrence of a first state of a control signal while said first and third terminals and said second and fourth terminals are respectively coupled together at the occurrence of a second state of said control signal.

13. The bi-directional neuron of claim 12 further comprising second means coupled to said control input of said switching circuit for providing said control signal for controlling the signal propagation direction therethrough.

14. A network having a plurality of inputs coupled for receiving a spatial vector of an input signal for providing a transformation thereof at a plurality of outputs, comprising:

a first plurality of conductors;

a second plurality of conductors;

a plurality of weighting elements interconnected between said first plurality of conductors and said second plurality of conductors in a predetermined manner;

first means coupled between the plurality of inputs and said first plurality of conductors for driving signals in either direction in response to a control signal, said first means comprising a switchable driver circuit including,

(a) first, second and third terminals, said first terminal being coupled to one of the first plurality of inputs, said second terminal being coupled to one of said first plurality of conductors,

(b) an amplifier having first and second inputs and having an output, said first input being coupled to said third terminal of said switchable driver circuit,

(c) a first switching circuit having first, second and third terminals and a control input, said first terminal being coupled to said one of said first plurality of inputs, said second terminal being coupled to said one of said first plurality of conductors, said third terminal being coupled to said second input of said amplifier, said control input being coupled for receiving said control signal, said first and third terminals being coupled together at the occurrence of said first state of said first control signal while said second and third terminals are coupled together at the occurrence of said second state of said control signal, and

(d) a resistor coupled between said output of said amplifier and said one of said first plurality of conductors; and

second means coupled between the plurality of outputs and said second plurality of conductors for driving signals in either direction in response to a second control signal.