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US 5,469,126 AGranted
I/Q-modulator and I/Q-demodulator
AssigneeNokia Mobile Phones Ltd.
InventorSimo Murtojarvi
Life of this patent
Estimating the term…
Abstract
An I/Q-modulator or I/Q demodulator circuit in which the modulating signals (2, 3) are input through the output phase transfer branches of the circuit. In relation to the RF-characteristics, a series resistor (16) and a series inductance (20) in the phase transfer circuits are grounded with small capacitors (23, 25). A capacitor (17) having a high impedance at the modulating frequency is located between the branches. Tho modulating signals are not summed through the capacitor (17), and, thus, their phase difference is not weakened.
Claims16
A circuit arrangement, comprising:
- a diode bridge having first and second terminals coupled to a first frequency signal and third and fourth terminals coupled to a first node of a first phase shift network and to a first node of a second phase shift network, respectively;
- said first phase shift network having a second node for passing therethrough a second frequency signal, said second node being coupled to ground potential through a first capacitance having a value that represents a high impedance to said second frequency signal;
- said second phase shift network having a second node for passing therethrough a third frequency signal, said second node of said second phase shift network being coupled to ground potential through a second capacitance having a value that represents a high impedance to said third frequency signal;
- and
- a third capacitance coupled between said first node of said first phase shift network and said first node of said second phase shift network, said third capacitance having a value that represents a high impedance to said second frequency signal and to said third frequency signal.
2 more elements
An I/Q modulator, comprising:
- an RF transformer comprising a primary coupled to a local oscillator (LO) frequency signal and a secondary;
- a diode bridge having first and second terminals coupled across said secondary and third and fourth terminals coupled to a first node of a first phase shift network and to a first node of a second phase shift network, respectively;
- said first phase shift network having a second node coupled to a first modulating frequency signal, said second node being coupled to ground potential through a first capacitance having a value that represents a high impedance to said first modulating frequency signal;
- said second phase shift network having a second node coupled to a second modulating frequency signal that has a 90.degree. phase relationship to said first modulating signal, said second node of said second phase shift network being coupled to ground potential through a second capacitance having a value that represents a high impedance to said second modulating frequency signal;
- a third capacitance coupled between said first node of said first phase shift network and said first node of said second phase shift network, said third capacitance having a value that represents a high impedance to said first modulating frequency signal and to said second modulating frequency signal;
- and
- an output terminal that is capacitively coupled to said first node of said first phase shift network and said first node of said second phase shift network.
4 more elements
Dependencies are inferred from the claim text.