Patent ID: 6600388
Filing Date: 2003-07-29
Classification: H01P,H03F

Abstract:
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 respectively including a first and a second varactor circuit, the first and second resonators each being resonant at a first predetermined resonant frequency that is a function of a first control voltage applied to each of the first and second varactor circuits, 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 respectively including a third and a fourth varactor circuit, the third and fourth resonators each being resonant at a second predetermined resonant frequency that is a function of a second control voltage applied to each of the third and fourth varactor circuits, the second predetermined resonant frequency being greater than the first predetermined resonant frequency, the second 3 dB quadrature hybrid coupler having a delay response as a function of 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.