NONLINEAR TRANSMISSION LINE WAVEFORM GENERATOR

• US 20010011930A1
• Filed: 02/05/1999
• Published: 08/09/2001
• Est. Priority Date: 02/05/1999
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: KINTIS, MARK, FONG, FLAVIA S., MAAS, STEPHEN A., KO, DANIEL K.
• Granted Patent: US 6,690,247 B2
• Time in Patent Office: Days
• US Class Current: 333/20
• CPC Class Codes: H03K 5/12 by steepening leading or trailing edges
• CPC Class Codes: H03K 5/156 Arrangements in which a continuous pulse train is transformed into a train having a desired pattern

Abstract

A nonlinear transmission-line waveform generator for generating a comb of frequencies and relatively short duration pulses, for example, in the range of picoseconds and tens of picoseconds, that are adapted to being utilized with ultra wideband radios in order to improve the bandwidth of such radios by an order of magnitude, for example, up to tens and even hundreds of GHz. In particular, the nonlinear transmission line waveform generator in accordance with the present invention consists of a microstrip or coplanar waveguide line. In accordance with an important aspect of the invention, the ΔC/ΔV characteristic of the nonlinear transmission line is matched to the frequency and amplitude of the input sinusoid. By matching the ΔC/ΔV characteristics of the nonlinear transmission line to the input sinusoid, the output of the nonlinear transmission line produces a comb of frequencies that are multiples of the input sinusoid frequency, making it suitable as a harmonic generator. The nonlinear transmission line can also be used to generate a relatively short duration pulses by disposing a shorting stub at the output. The shorting stub causes the waveform to be reflected 180° out of phase so that it cancels the trailing edge of the original output from the nonlinear transmission lines to form a short duration pulse in the picosecond range. The length of the stub determines the width of the resultant output pulse.

Claims

1. A method for generating a waveform comprising the steps of:

(a) providing a nonlinear transmission line having an input and an output and a predetermined C/V characteristic; and

(b) applying a sinusoidal input voltage to said nonlinear transmission line in which the amplitude and frequency of said sinusoidal input voltage are matched to said C/V characteristic.

2. The method as recited in

claim 1

, wherein said nonlinear transmission line includes a microstrip.

3. The method as recited in

claim 1

, wherein said nonlinear transmission line includes a coplanar waveguide.

4. The method as recited in

claim 1

, wherein said nonlinear transmission line incudes one or more diodes.

5. The method as recited in

claim 1

, further including the step of disposing a stub at the output of said nonlinear transmission line, said stub coupled between said output and ground, the length of said stub determining the width of said resultant output pulse.

6. A signal generator comprising:

a nonlinear transmission line having an input and an output and a predetermined Δ

C/Δ

V characteristic; and

means for generating a sinusoidal input waveform, the frequency and amplitude of said input waveform selected to match said Δ

C/Δ

V characteristic of said nonlinear transmission line.

7. The signal generator as recited in

claim 6

, wherein said nonlinear transmission line includes a microstrip.

8. The signal generator as recited in

claim 6

, wherein said nonlinear transmission line includes a coplanar waveguide.

9. The signal as recited in

claim 6

, wherein said nonlinear transmission line includes one or more diodes.

10. The signal generator as recited in

claim 6

, further including a shorting stub disposed at the output of said nonlinear transmission line.

11. A signal generator comprising:

a nonlinear transmission line having an input and an output and a predetermined Δ

C/Δ

V characteristic;

means for generating an input sinusoidal waveform whose amplitude and frequency characteristics are matched to said Δ

C/Δ

V characteristics of said nonlinear transmission line; and

means coupled to the output of said nonlinear transmission line for manipulating the output pulse from said nonlinear transmission line in order to provide a resultant pulse having a pulse width less than the pulse width of said output pulse.

12. The signal generator as recited in

claim 11

, wherein said manipulating means includes a shorting stub coupled to the output of said nonlinear transmission line.

13. The signal generator as recited in

claim 11

, wherein said manipulating means includes a resonant circuit.

14. The signal generator as recited in

claim 13

, wherein said resonant circuit is tuned to the center frequency of the output frequency band of said device.