Delay line filters using multiple in-line four-input couplers
AssigneeDelaware Capital Formation, Inc.
InventorRafi Hershtig
Life of this patent
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Abstract
A delay circuit for the secondary path of a feed-forward high power amplifier is disclosed. A first 3 dB quadrature hybrid coupler is coupled to first and second resonator circuits that are resonant at a first resonant frequency. The output of the first hybrid coupler is coupled to the input of a second 3 dB quadrature hybrid coupler. The second hybrid coupler is coupled to third and fourth resonator circuits that are resonant at a second resonant frequency that is greater than the first resonant frequency. The overall combined delay response of the first hybrid coupler and the second hybrid coupler appearing at the fourth node of the second hybrid coupler is substantially constant between the first resonant frequency and the second resonant frequency.
Claims8
A delay circuit, comprising:
- a first 3 dB quadrature hybrid coupler having a first node receiving an input signal, a second node that is coupled to a first resonator circuit, a third node that is coupled to a second resonator circuit and a fourth node that is an output node, the first and second resonators being resonant at a first resonant frequency, the first 3 dB quadrature hybrid coupler having a delay response as a function of frequency that is substantially linearly decreasing for increasing frequency greater than the first resonant frequency;
- and
- a second 3 dB quadrature hybrid coupler having a first node coupled to the fourth node of the first 3 dB quadrature hybrid coupler, a second node that is coupled to a third resonator circuit, a third node that is coupled to a fourth resonator circuit, and a fourth node that is an output node, the third and fourth resonators being resonant at a second resonant frequency, the second resonant frequency being greater than the first resonant frequency, the second 3 dB quadrature hybrid coupler having a delay response as a function a frequency that is substantially linearly decreasing for increasing frequency less than the second resonant frequency,
- the overall combined delay response of the first 3 dB quadrature hybrid coupler and the second 3 dB quadrature hybrid coupler appearing at the fourth node of the second 3 dB quadrature hybrid coupler being substantially constant between the first resonant frequency and the second resonant frequency.
A feed-forward power amplifier, comprising:
- a main signal path;
- and
- a secondary signal path having a delay circuit comprising
- a first 3 dB quadrature hybrid coupler having a first node receiving an input signal, a second node that is coupled to a first resonator circuit, a third node that is coupled to a second resonator circuit and a fourth node that is an output node, the first and second resonators being resonant at a first resonant frequency, the first 3 dB quadrature hybrid coupler having a delay response as a function of frequency that is substantially linearly decreasing for increasing frequency greater than the first resonant frequency;
- and
- a second 3 dB quadrature hybrid coupler having a first node coupled to the fourth node of the first 3 dB quadrature hybrid coupler, a second node that is coupled to a third resonator circuit, a third node that is coupled to a fourth resonator circuit, and a fourth node that is an output node, the third and fourth resonators being resonant at a second resonant frequency, the second resonant frequency being greater than the first resonant frequency, the second 3 dB quadrature hybrid coupler having a delay response as a function a frequency that is substantially linearly decreasing for increasing frequency less than the second resonant frequency,
- the overall combined delay response of the first 3 dB quadrature hybrid coupler and the second 3 dB quadrature hybrid coupler appearing at the fourth node of the second 3 dB quadrature hybrid coupler being substantially constant between the first resonant frequency and the second resonant frequency.
Dependencies are inferred from the claim text.