Quadrature oscillator with high linearity

A technology of oscillators and quadrature signals, applied in the field of controlling the oscillation frequency of in-phase signals and quadrature signals, can solve problems such as inability to work correctly and limit correct operation

Active Publication Date: 2008-06-04
NXP BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This known IQ oscillator works well at low frequencies, but does not work correctly at higher frequencies of a few GHz due to the expected large parasitic capacitance of the LC tank (LCtank)
In fact, the inductor will have two gate-source capacitances in parallel, which limits correct operation at higher frequencies

Method used

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  • Quadrature oscillator with high linearity
  • Quadrature oscillator with high linearity
  • Quadrature oscillator with high linearity

Examples

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Embodiment Construction

[0029] A preferred embodiment will now be described based on a differential Colpitts-type IQ oscillator, which may be used, for example, in the transceiver circuits described below.

[0030] Figure 1 shows a transceiver circuit for wireless applications like WLAN (Wireless Local Area Network) or WPAN (Wireless Personal Area Network). The transceiver is a homodyne transceiver with zero intermediate frequency (IF) on the receiver side and on the transmitter side.

[0031] A signal or data stream received via antenna array 90 is provided to low noise amplifier (LNA) 82 through matched filter 68 . The amplified output signal of the low noise amplifier 82 is split into first and second branches, each branch comprising a sub-harmonic mixer 72, 74, wherein the received signal is combined with the I and Q oscillating signals of the IQ VCO 10 mix. The I and Q oscillating signals are phase adjusted at the IQ phase circuit 52 . The respective low-pass filters 62, 64 and downconverted ...

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Abstract

The present invention relates to an oscillator circuit and a method of controlling the oscillation frequency of an in-phase signal and a quadrature signal. First oscillator means (2) with a first differential oscillator circuit and a first differential coupling circuit are provided for generating the quadrature signal. Furthermore, second oscillator means (4) with a second differential oscillator circuit and a second differential coupling circuit are provided for generating the in-phase signal. A frequency control means is provided for varying the oscillation frequency of the in-phase signal and the quadrature signal by controlling at least one of a common-mode current and a tail current of the first and second oscillator means. Thereby, a high-frequency IQ oscillator with high linearity is obtained.

Description

technical field [0001] The present invention relates to an oscillator circuit for generating in-phase and quadrature signals, and a method for controlling the oscillation frequency of the in-phase and quadrature signals. Background technique [0002] High frequency voltage controlled oscillators (VCOs) are widely used in integrated circuits ranging from clock recovery in high data rate optical communications to frequency synthesizers in wireless communications. Frequency tuning of these VCOs can be achieved using varactor diodes. [0003] IQ (in-phase / quadrature) oscillators are important building blocks for radio frequency (RF) transceivers. For example, when quadrature signals are required in the IQ downconverter and in the transmitter part of the data and clock recovery (DCR) unit, few solutions are applicable. Traditional techniques are based on generating a signal at a double frequency followed by a divide by 2. However, this technology is hampered by technical limit...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03B5/12
CPCH03B27/00
Inventor 米哈伊·A·T·桑托利努爱德华·F·斯蒂克沃罗特
Owner NXP BV
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