5

MRFIC2002

MOTOROLA RF DEVICE DATA

VCC, SUPPLY VOLTAGE (V)

Figure 10. ICC versus VCC

14

4

3.4

3

5

8

6

4

2

0

Figure 11. ICC versus Enable Voltage

4.2

VEN, ENABLE VOLTAGE (V)

12

10

8

3.8

4.6

TA = + 85°C

25

°C

– 35

°C

1

0

5

3

24

TA = 85°C

VCC = 3 V

6

– 35

°C

25

°C

APPLICATIONS INFORMATION

DESIGN PHILOSOPHY

The MRFIC2002 was designed to have excellent LO and

spurious rejection. This is accomplished by using a double-

balanced configuration and using a symmetrical die layout.

To eliminate the need for external baluns or decoupling

elements, the unused LO and IF ports are decoupled inter-

nally. Only one of the RF outputs is used, eliminating the

need for an external balun on the RF port as well. Also, the

RF port is buffered to provide a 50 ohm output impedance.

External matching is required for the LO and IF ports.

To minimize current drain in various TDD/TDMA systems,

two methods of enabling/disabling the MRFIC2002 are pro-

vided: one that is TTL/CMOS compatible and one that is trig-

gered from a ramp, such as the one provided in the

MRFIC2004. The former method must be used if a ramp is

not available. The latter method is more desirable since the

MRFIC2002 can remain off during guard times and while in

idle mode.

THEORY OF OPERATION

Matching the LO port to 50 ohms can be done several

ways. The recommended approach is a series inductor as

close to the IC as possible. The inductor value is small

enough (~8 –15 nH depending on LO frequency) to be

printed on the board. A DC block is required and should not

be placed between the inductor and IC since this will prevent

the inductor from being placed close enough to the IC to pro-

vide a good match.

The IF port is approximately 500 ohms resistive in parallel

with 1.3 pF of capacitance. If 50 ohms is the desired IF port

impedance, a shunt capacitor followed by a series inductor

will provide the transformation. A DC block is required and

can be placed on either side of the matching network.

The RF port is nearly 50 ohms resistive in series with a

small amount of inductive reactance, which results in an

8 –11 dB return loss. However, a series 5.6 pF capacitor

placed as close to the IC as possible will typically provide

greater than a 15 dB return loss. The series capacitor also

serves as a DC block which is required.

Supply decoupling must be done as close to the IC as pos-

sible. A 1000 pF capacitor is recommended. An additional

100 pF capacitor and an RF choke are recommended to

keep the RF and LO signals off the supply line.

For systems that use a ramp, like the one provided in the

MRFIC2004, enabling/disabling can be done by applying the

ramp voltage to the VRAMP pin which trips the IC between

0.6 and 1.0 volts. The Enable pin must either be tied high or

to the inverse of the receiver enable control line, RXEN. An

inverter is provided in the MRFIC2004 to invert RXEN.

For systems that do not use a ramp, the VRAMP pin can

be left open circuited and enabling/disabling the MRFIC2002

can be done with its TTL/CMOS compatible Enable pin. The

trip point is between 1.0 and 2.0 volts.

EVALUATION BOARDS

Evaluation boards are available for RF Monolithic Inte-

grated Circuits by adding a “TF” suffix to the device type.

For a complete list of currently available boards and ones

in development for newly introduced product, please con-

tact your local Motorola Distributor or Sales Office.