7-72

Applications Example

Figure 4 shows an applications example of the HSP50307.

The MCLK source operates at 25.6MHz, and the RCLK

operates at 2.048MHz. 0.1

µF capacitors are connected from

the IBBOUT to IBBIN and the QBBOUT to QBBIN, providing

AC coupling to the Analog Upconverter Section of the

HSP50307.

The control processor sends the 23-bit control word via the

three-wire interface. The data source receives the 256kHz

TXCLK from the HSP50307 and transmits data and enable

signal at the 256kHz rate.

The DAC_REF and VCM_REF are connected to 0.1

µF

capacitors to ground. Each of the differential drivers are

loaded with a 37.5

Ω resistor and a 0.1µF capacitor. The

37.5

Ω resistors provide matching to the 75Ω cable. The

capacitors perform AC coupling. The drive paths are sent to

the cable transformer for data transmissions.

Table 3 shows the general functional specifications for the

applications example shown in Figure 4. It gives an overview

of what is being accomplished but does not specify an exact

carrier frequency or other programmable functions. These

specifications are met given a valid control word combination

and the applications circuit shown in Figure 4. Table 4 sum-

marizes the performance of the applications example shown

in Figure 4. Again, these specifications are met given a valid

programmed mode.

NOTE: The HSP50307 is sensitive to layout. Users must

make sure the input signals do not couple back into the

output signals. The performance of the HSP50307 is

also sensitive to the decoupling capacitors between

1) QBBOUT and QBBIN and 2) IBBOUT and IBBIN. The

values shown in Figure 4 are recommended.

0.1

µF

CCLK

C_EN

DVCC

RCLK

AGND

VCO_IN

AVCC

MOD_OUT-

MOD_OUT+

AVDD

AGND

CDATA

PD_OUT

VCO_SET

28

27

26

25

24

23

22

21

20

19

18

17

16

15

1

2

3

4

5

6

7

8

9

10

11

12

13

14

MCLK

TX_EN

TX_DATA

RESET

DGND

AGND

QBBOUT

QBBIN

IBBIN

DAC_REF

VCM_REF

TXCLK

AVCC

IBBOUT

0.1

µF

0.1

µF

0.1

µF

0.1

µF

DGND

AGND

25.6MHz

OSC

DATA

SOURCE

0.1

µF

DGND

CONTROL

PROC.

2.048MHz

OSC

0.01

µF

2k

Ω

6.25k

Ω

100pF

0.01

µF

37.5

Ω 0.1µF

CABLE

TRANSFORMER

37.5

Ω 0.1µF

0.1

µF

AGND

FIGURE 4. APPLICATIONS EXAMPLE OF THE HSP50307

RFOUT

HSP50307