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978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com

Application Support: apps@hittite.com

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HMC702LP6CE

v07.0411

14 GHz 16-BIT FRACTIONAL-N PLL

Setting register gpo_sel=10 (Reg1B<3:0> table 37) assigns the three lsb’s of the delta sigma modulator output

to GPo<3:1>, where GPo1 is the lsb. this feature allows the possibility of using the HMc702LP6cE as a general

purpose digital delta sigma modulator for many possible applications.

External VCO

the HMc702LP6cE is targeted for ultra low phase noise applications with an external Vco. the synthesizer has

been designed to work with Vcos that can be tuned nominally over 0.5 to 4.5 Volts on the varactor tuning port with a

+5V charge pump supply voltage. Slightly wider ranges are possible with a +5.5V charge pump supply or with slightly

degraded performance.

External VCO with Active Inverting OpAmp Loop Filter

an external opamp active filter is required to support external Vcos with tuning voltages above 5V. if an inverting

opamp is used with a positive slope Vco, phase_sel reg05h <0> = 1 table 16 must be set to invert the PFD phase

polarity and obtain correct closed loop operation.

Figure 9. Conventional Synthesizer with VCO