Patent US5694093A successfully refreshed from Google Patents.
US5694093A
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Wideband IQ modulator with RC/CR automatic quadrature network
Assignee: Agilent Technologies Inc
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Filing: 1995-11-07
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Granted: 1997-12-02
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Expires: 2015-11-07
Abstract
Abstract An IQ modulator incorporates a quadrature network that is responsive to a frequency dependent control signal and that has in-phase and quadrature signals that are of equal amplitude and in exact quadrature over a wide range of applied frequencies. The quadrature network includes RC and CR phase shifters whose C's are fixed capacitors of equal value and whose R's are made equal to each other and to the capacitive reactance of the C's by the action of the frequency dependent control signal. The R's may be FET's. The frequency dependent control signal may be generated without express knowledge of the applied frequency by a servo loop that nulls out the amplitude difference between the in-phase and quadrature outputs from the quadrature network; it may also be generated from a look-up table as an express function of frequency. The frequency dependent control signal is split into separate instances that are applied to each R, and an offset may be introduced therebetween to provide extreme precision. The offset may be fixed or programmatically controlled as a function of frequency. Varactors may be used to provide variable C's in cooperation with fixed R's. The entire circuit may be fabricated as a GaAs IC for use in the frequency range of 200 MHz to 3GHz.
Inventors
- 👤 Marcus K. DaSilva
- 👤 Andrew M. Teetzel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 07:29
CPC Classifications
H; H03; H03C; H03C5/00; H03C1/00; H03C1/52; H03C3/00; H03C3/38; H03C3/40; H03H; H03H11/00; H03H11/02; H03H11/16; H03H11/18; H03H11/22; H03C1/02; H03C1/60; H03C2200/00; H03C2200/0004; H03C2200/0016; H03C2200/0037; H03C2200/0058; H03D; H03D1/00; H03D1/22; H03D1/2245; H03D3/00; H03D3/007
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
312 words
A modulator comprising: a quadrature circuit having a signal input that receives an input signal to be modulated and having first and second quadrature outputs at which respectively appear first and second quadrature signals of the same frequency as the input signal but which are in quadrature with each other, the quadrature circuit also having first and second control inputs that respectively receive first and second control signals, the quadrature circuit responsive to the first control signal by producing corresponding alterations in the amplitude of the first quadrature signal and to the second control signal by producing corresponding alterations in the amplitude of the second quadrature signal; first and second amplitude detectors respectively coupled to the first and second quadrature outputs and producing respective first and second amplitude level signals; a difference amplifier having inputs coupled to the first and second amplitude level signals and having a difference output; an offset circuit coupled to the difference output and that produces the first and second control signals, the amplitude of the first control signal equal to that of the difference signal increased by a selected amount and the amplitude of the second control signal equal to that of the difference signal decreased by the selected amount; a first multiplier having an input coupled to the first quadrature signal and another input receiving a first component of a pair of signals representing program information to be modulated onto the input signal, and producing therefrom a first multiplier output signal; a second multiplier having an input coupled to the second quadrature signal and another input receiving the remaining second component of the pair of signals representing program information, and producing therefrom a second multiplier output signal; and a summer having first and second inputs respectively coupled to the first and second multiplier output signals and having an output at which appears the modulated input signal.
Claim 2
Dependent Claim
312 words
A modulator comprising: a quadrature circuit having a signal input that receives an input signal to be modulated and having first and second quadrature outputs at which respectively appear first and second quadrature signals of the same frequency as the input signal but which are in quadrature with each other, the quadrature circuit also having first and second control inputs that respectively receive first and second control signals, the quadrature circuit responsive to the first control signal by producing corresponding alterations in the amplitude of the first quadrature signal and to the second control signal by producing corresponding alterations in the amplitude of the second quadrature signal; first and second amplitude detectors respectively coupled to the first and second quadrature outputs and producing respective first and second amplitude level signals; a difference amplifier having inputs coupled to the first and second amplitude level signals and having a difference output; an offset circuit coupled to the difference output and that produces the first and second control signals, the amplitude of the first control signal equal to that of the difference signal increased by a selected amount and the amplitude of the second control signal equal to that of the difference signal decreased by the selected amount; a first multiplier having an input coupled to the first quadrature signal and another input receiving a first component of a pair of signals representing program information to be modulated onto the input signal, and producing therefrom a first multiplier output signal; a second multiplier having an input coupled to the second quadrature signal and another input receiving the remaining second component of the pair of signals representing program information, and producing therefrom a second multiplier output signal; and a summer having first and second inputs respectively coupled to the first and second multiplier output signals and having an output at which appears the modulated input signal.
Claim 3
Dependent Claim
18 words
A modulator as in claim 1 wherein the first and second multipliers are ring mixers comprised of FET's.
Claim 4
Dependent Claim
15 words
A modulator as in claim 2 wherein the FET's comprising the ring mixers are unbiased.
Claim 5
Dependent Claim
16 words
A modulator as in claim 1 wherein the first and second multipliers comprise double balanced mixers.
Claim 6
Dependent Claim
15 words
A modulator as in claim 1 wherein the modulator is constructed as an integrated circuit.
Claim 7
Dependent Claim
13 words
A modulator as in claim 5 wherein the integrated circuit is of GaAs.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-12-01 | 2001-06-02 | 2001-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-12-01 | 2005-06-02 | 2005-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-12-01 | 2009-06-02 | 2009-12-02 | $7700.00 | Window Closed / Lapsed |