You are designing a VCO that will be used in the synthesizer of an 802.11b/g wir

Question

You are designing a VCO that will be used in the synthesizer of an 802.11b/g wireless LAN card. The synthesizer will tune the local oscillator across the 2.400 – 2.485 GHz ISM band. Assume a reasonable IF frequency for your WLAN card and specify the LO tuning range. Specify whether you will be using high-side or low-side injection, based on where you anticipate the image response of the receiver will be less of a problem (Remember, WLAN cards have become small and cheap, so a system design will be highly constrained, yet must co-exist with other services). Based on this tuning range, design the tuning circuit for the oscillator using a varactor-tuned LC oscillator. You might decide that a Hartley or Colpitts oscillator make the design simplest, but specify which you will be using. Pick reasonable values for the inductor(s), capacitor(s) and varactor diode capacitance to tune the entire band.

Note: you might decide that it is preferable to tune the VCO at a lower frequency and multiply the output frequency up to the intended range.

Explanation / Answer

VCO tuning voltage

(~1.35 V) and around room temperature (20C–40C),

temperature coefficient is about 0.037/C.

802.11a low band
freq range 5.15-5.35ghz
vco tuning range 10.36-10.64
802.11a high band
   freq range 5.725-5.825
   vco tuning range 11.49-11.61

The self-resonance frequency is set to 6 GHz, about fvco/2

capacitor array enabled the L-C VCO to have thefrequency tuning range of 30%, from 8.64 to 11.62 GHz

inductor working at 10 GHz.

as o/p of vco is 12hz the varactor will be very high

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