Frequency synthesizer and multiplier circuit arrangement for a radio telephone
First Claim
1. A circuit arrangement for a radio telephone comprising at least one UHF frequency synthesizer circuit (UHF1, UHF2) and a VHF synthesizer circuit (VHF) each including an output therefrom and an oscillator (71) having a reference frequency output therefrom, said at least one UHF synthesizer circuit and said VHF synthesizer circuit each including a corresponding Phase Locked Loop (PLL) circuit (21, 22) (23) coupled to said oscillator (71) and responsive to said reference frequency output therefrom, multiplier means (11, 12) for frequency multiplying coupled to said output of said at least one UHF synthesizer circuit and responsive to a first control signal (select X1/X2) to change the frequency of a signal output from said multiplier means (11, 12), thereby selectively changing the operational frequency range of the circuit arrangement and an I/Q modulator means (13) responsive to the output of said VHF synthesizer circuit to provide a modulating signal.
1 Assignment
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Accused Products
Abstract
The invention relates to a general purpose circuit arrangement for a radio telephone wherein the universal application possibilities have been provided by phase-locked circuits (PLL1 to PLL3) and by a multiplier circuit (11, 12) that can be controlled (signals Select x1/x2 and Synte sel./Data) by the processor of the mobile telephone. The second harmonic or the fundamental frequency is selected by the multiplier circuit from the VCO oscillators (61, 62). In this way, the frequencies of the synthesizer circuits (UHF1, UHF2, UHF3) can be set independently of each other and according to the requirements of the respective cellular networks. The central circuits are advantageously integrated into four IC circuits (IC1 to IC4).
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Citations
10 Claims
- 1. A circuit arrangement for a radio telephone comprising at least one UHF frequency synthesizer circuit (UHF1, UHF2) and a VHF synthesizer circuit (VHF) each including an output therefrom and an oscillator (71) having a reference frequency output therefrom, said at least one UHF synthesizer circuit and said VHF synthesizer circuit each including a corresponding Phase Locked Loop (PLL) circuit (21, 22) (23) coupled to said oscillator (71) and responsive to said reference frequency output therefrom, multiplier means (11, 12) for frequency multiplying coupled to said output of said at least one UHF synthesizer circuit and responsive to a first control signal (select X1/X2) to change the frequency of a signal output from said multiplier means (11, 12), thereby selectively changing the operational frequency range of the circuit arrangement and an I/Q modulator means (13) responsive to the output of said VHF synthesizer circuit to provide a modulating signal.
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10. A radio frequency circuit for a digital mobile telephone comprising a synthesizer means including a UHF range signal synthesizer circuit for providing first and second local oscillator signals and a VHF range signal synthesizer circuit,
a reception branch for receiving a radio frequency signal including a first mixer (31) having a first input connected to said radio frequency signal and a second input connected said first local oscillator signal of said synthesizer means for providing an intermediate frequency output signal, and processing circuits connected to said intermediate frequency output signal of said first mixer; -
a transmission branch including a second mixer (14), a source (13) of digital modulating signal selectively connected to said VHF range signal synthesizer, said second mixer (14) having a first input connected to said source (13) of digital modulating signal and a second input connected to said second local oscillator signal of said UHF range signal synthesizer circuit for providing an output RF transmission signal, said second mixer having a third input; a source of analogue modulating signal selectively connected to said third input of said second mixer; and wherein said synthesizer means further comprises PLL loop circuits connected to a reference oscillator circuit, a source of control signal, and multiplier means connected to the output of said UHF range synthesizer circuit and to said source of control signal for changing the frequency characteristics of said multiplier means.
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Specification