MC13144

4

MOTOROLA RF/IF DEVICE DATA

APPLICATIONS INFORMATION

Evaluation PC Board

The evaluation PCB is very versatile and is intended to

be used across the entire useful frequency range of this

device. The PC board layout accommodates all SMT

components on the circuit side (see Circuit Side Component

Placement View).

Component Selection

The evaluation PC board is laid out for the 4DFA (2 pole

SMD Type) and 4DFB (3 pole SMD Type) filters which are

available for applications in Cellular and GSM, GPS (1.2 to

1.5 GHz), DECT, PHS and PCS (1.8 to 2.0 GHz) and

ISM Bands (902 to 928 MHz and 2.4 to 2.5 GHz). In the

926.5 MHz Application Circuit, a ceramic deielectric filter

is used (Toko part # 4DFA–926A10).

LNA Input/Output

The LNA input impedance is the base of a common emitter

cascode amplifier. The LNA output is the collector of the

cascode stage and it is loaded with a series resistor of 400

Ω

and a capacitor of 10 pF to provide stability.

Digitally Programmable Bias/Enable

The LNA is enabled by a 2 bit (En1 and En2)

programmable bias circuit. The internal circuit shows the

comparator circuit which programs the internal regulator. The

logic table below shows the bias and typical performance.

f = 900 mHz

ICC/Gain

En2 Low

En2 High

En1 Low

0 mA/–22 dB

1.2 mA/9.2 dB

En1 High

3.4 mA/13 dB

8.2 mA/17 dB

f = 1900 mHz

ICC/Gain

En2 Low

En2 High

En1 Low

0 mA/–22 dB

1.2 mA/7.5 dB

En1 High

3.4 mA/10 dB

8.2 mA/13 dB

Input/Output Matching

A typical application at 900 MHz yields 17 dB gain and

1.4 dB noise figure. In this circuit a series inductor of 5.6 nH

is used to match the input and a shunt inductor of 8.2 nH

which also serves as an RFC and a series capacitor of 0.9 p

is used to match the LNA output to 50

Ω load impedance.

It may be desirable to use a RF ceramic or SAW filter after

the LNA when driving a mixer to provide image frequency

rejection. The image filter is selected based on cost, size and

performance tradeoffs. Typical RF filters have 3.0 to 5.0 dB

insertion loss. Interface matching between the RF input, RF

filter and the mixer is shown in Application Circuit and the

Component Placement View.

A typical application at 1900 MHz yields 13 dB gain and

2.7 dB noise figure. In this circuit a series inductor of 5.6 nH

and a series capacitor of 1.0 pF are used to match the input

and a shut inductor of 2.0 nH and a series capacitor of 2.0 pF

are used to match the LNA output to 50

Ω load impedance.

Figure 2. MC13144D Application Circuit

(926.5 MHz)

8

RF

Input

En1

RF

Output

8.2 nH

VCC

En2

5.6 nH

47 p

100 p

100 p

100 n

76

5

12

3

4

47

39 nH

8.2 nH

Toko

Ceramic

Filter

0.4 p

VCC

1.0 M

MC13144D

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

ARCHIVED BY FREESCALE SEMICONDUCTOR, INC. 2005