HMC862A Data Sheet
Rev. 0 | Page 12 of 15
THEORY OF OPERATION
The HMC862A is a wideband, configurable RF divider with
minimal additive phase noise.
The divide ratio, N, can be programmed to N = 1, 2, 4, or 8 by
setting the digital input pins—S0, S1, and S2—to the logic high
(1) or logic low (0) states indicated in Table 5.
Table 5. Programming Truth Table for Frequency Division
Ratios
1
S0 S1 S2 Divide Ratio (N)
0 0 0 1
1 0 0 2
1 1 0 4
1 1 1 8
1
0 means logic low and 1 means logic high.
The HMC862A does not support any other combination of the S0,
S1, and S2 programming states other than those listed in Table 5.
Using other programming states causes the HMC862A to
generate an unstable output.
Enable the HMC862A by applying a voltage (V
CC
) to the supply
pins, V
CC
. These pins are internally connected.
Note that the V
CC
voltage must be applied before the logic level
signals (S0, S1, and S2) can be driven to a logic high to prevent
the ESD diodes from turning on.
INPUT INTERFACE
The HMC862A can be driven by differential or single-ended
input signals, and can provide differential or single-ended
output signals.
Figure 28 shows the input interface schematic for the IN and
IN
pins.
IN IN
50
50
13599-053
Figure 28. Input Interface Schematic
For differential input signals, ac couple the IN and
IN
pins as
shown in Figure 28. Off-chip termination is not required because
the IN and
IN
pins have internal 50 Ω termination resistors.
For single-ended input signals, ac couple the IN input. AC
ground the
IN
pin as close to the
IN
pin as possible.
IN
IN
IN
IN
13599-054
Figure 29. Recommended Input Configuration for Single-Ended Operation
(Left) and Differential Operation (Right)
OUTPUT INTERFACE
Figure 30 shows the output interface schematic for the OUT
and
OUT
pins.
OUT
OUT
50 50
13599-055
Figure 30. Output Interface Schematic
To provide a differential output or two single-ended outputs, ac
couple the OUT and
OUT
pins. Off-chip termination is not
required because the OUT and
OUT
pins have internal 50 Ω
termination resistors.
If only one output pin is used, connect the unused output pin to
ground through a capacitor and a 50 Ω termination
OUT
OUT
OUT
OUT
13599-056
Figure 31. Recommended Output Configuration for Single-Ended Operation
(Left) and Differential Operation (Right)
