Integrated VCO switch

Abstract

The invention relates to a VCO (100, 130) integrated in a radio ASIC, wherein a switch (180, 60, 70, 80, 90) is arranged for switching the centre frequency of the VCO between arbitrary frequency bands to be able to perform band switching and / or frequency tuning. In a preferred embodiment, the switch switches the centre frequency of the VCO (100, 130) between the DCS-band and the PCS-band. Thus, instead of having one VCO for the DCS-band and another one for the PCS-band, the invention uses only one VCO for both bands saving a lot of valuable space on the ASIC.

Description

Technical field [0001] The present invention relates to an integrated VCO preferably used in a radio ASIC. Background technique [0002] In a radio ASIC, a stable frequency that moves information up and down in frequency is required. Usually, by using a PLL (Phase Locked Loop) circuit to lock an unstable VCO (Voltage Controlled Oscillator) at a very stable reference frequency, such as 13MHz, this stable frequency can be generated. in figure 1 In, a PLL-circuit is disclosed, which includes a phase detector 150, a filter and amplifier 160, a VCO, and a frequency divider with a frequency division factor of 72. The PLL tries its best to keep the input I and II of the phase detector at the same signal frequency. For example, if the input I of the phase detector 150 has a reference frequency of 13 MHz (13 MHz-clock in a telephone), the other input II of the phase detector 150 should have the same frequency as much as possible. This means that the VCO must operate at a frequency of 72*...

AI Technical Summary

Problems solved by technology

One problem that arises when integrating a VCO on an ASIC is that there are no external components that can be used to fine-tune the VCO frequency

Another problem is that if a large frequency band is covered, two separate VCOs must be used, which necessarily takes up a lot of space on the radio ASIC

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