5.5-8.4 GHz GaAs MMIC
Voltage Controlled Feedback Oscillator
May 2005 - Rev 05-May-05
9OSC0315
Typical Application (cont.)
Fine Phase Adjust
The Fine Phase Adjust control line is an analog input signal used to finely adjust the phase of the loop.This phase-shifter consists of a Lange
coupler and two arrays of PN varactor diodes.The insertion phase of the Lange coupler is controlled by variation of the capacitance
presented by the varactor diode arrays.
As shown in Figure 9, the fine phase adjustment is used to finely control the phase delay which is present between the consecutive phase
delay points determined by the coarse phase control. It is important that the fine phase control adjustment range covers the widest gap
which can occur between coarse phase adjustment points.This is necessary to avoid“dead spots”in the tuning range of the oscillator,
caused by phase delay points that can never be reached by the fine/coarse phase tuning. Because the phase difference between adjacent
steps in the coarse phase adjustment can vary over the 360° range, over frequency, and over temperature, it is expected that the fine
adjustment be set to tune over a wider range then the ideal case of just one gap (see Figure 9). In this case, note that steps must be taken
when detecting and locking to a PLL lock signal to avoid contention between the fine and coarse phase adjustment loops, as well as
avoiding false lock conditions.
Figure 10 shows the tuning characteristics of the Fine Phase Adjustment.
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Mimix Broadband, Inc., 10795 Rockley Rd., Houston,Texas 77099
Tel: 281.988.4600 Fax: 281.988.4615 mimixbroadband.com
Characteristic Data and Specifications are subject to change without notice. ©2005 Mimix Broadband, Inc.
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