HMC700LP4 Datasheet, PDF (13/36 Pages) Hittite Microwave Corporation – 8 GHz 16-Bit Fractional-N PLL

v07.0411
HMC701LP6CE
8 GHz 16-Bit Fractional-N PLL
0
Δ∑ Modulator Outputs (gpo_sel=10)
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 HMC701LP6CE as a general
purpose digital delta sigma modulator for many possible applications.
External VCO
The HMC701LP6CE 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. An external opamp active filter is required to support VCOs with tuning voltages above 5V.
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.
Temperature Sensor
The HMC701LP6CE features a built in temperature sensor which may be used as a general purpose temperature
sensor.
The temperature sensor is enabled via tsens_spi_enable (Reg1Eh=1 Table 40) and when enabled draws 2 mA.
The temperature sensor features a built in 3-bit quantizer that allows the temperature to be read in register tsens_
temperature (Reg21h Table 43). The temperature sensor data converter is not clocked. Updates to the temperature
sensor register are made by strobbing register tsens_spi_strobe (Reg00h<3> Table 11). The 3-bit quantizer operates
over a -40°C to +100°C range as follows:
Tn = floor {(Temperature +40) / 17.5 where Tn is the decimal value of register tsens_temperature}
(EQ 7)
7
6
5
4
3
2
1
0
-40
-20
0
20
40
60
TEMPERATURE (°C)
80
100
Figure 9. Typical Temperature Sensor Quantizer output
Temperature sensor slope is 17.5 mV/lsb. Absolute tolerances on the temperature sensor thresholds may vary by up
to ±10°C worst case.
Nominal temperature is given by:
(EQ 8)
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