ML2751

7

January, 2000

PRELIMINARY

PRELIMINARY DATASHEET

OPERATION MODES AND CONTROL INTERFACE

DESCRIPTION

The signals FEEN and PAON determine the mode of

operation. The three standard modes of operation are

STANDBY, TRANSMIT, and RECEIVE. The control logic is

shown in Table 1.

STANDBY: All circuits are off (LNA bias off), PIN driver

outputs are Tri-stated.

TRANSMIT: PA and the PIN diode drivers are enabled.

The LNA is off (zero current).

RECEIVE: The LNA bias circuits and the PIN diode drivers

are enabled, PA is disabled.

In addition to the two mode control inputs, FEEN and

PAON, there is an analog voltage input that can be used

to set the power output of the amplifier. The voltage range

Table 1. Control Logic

required to set the output power level can be controlled

by an external resistor.

Note that the ML2751 has an internal power amplifier

ramp-on and ramp-off circuit. The power amplifier turn

on/off relative to the ramp is shown in Figure 3. The ramp-

on starts when the PA is enabled, the ramp-off starts when

it is disabled.

Two outputs, PIN and PINB, are provided from the

ML2751 to drive the external PIN diodes in the Transmit/

Receive switch. The timing for these voltage outputs is

shown in Figure 3 relative to the control pins FEEN and

PAON.

Figure 3. Signals vs. Mode Relationships

FEEN

PAON

PIN

PINB

3µs

3µs

PA RF

Envelope

Tri-state

Tri-state

STANDBY

STANDBY

TRANSMIT

RECEIVE

N

E

E

FN

O

A

Pe

d

o

MN

I

PB

N

I

PA

N

LA

P

0X

Y

B

D

N

A

T

Se

t

a

t

s

-

i

r

Te

t

a

t

s

-

i

r

Tf

f

Of

f

O

10

E

V

I

E

C

E

RA

m

0

1

-

/

C

C

VA

m

0

1

+

/

C

C

Vn

Of

f

O

11

T

I

M

S

N

A

R

TA

m

0

1

+

/

C

C

VA

m

0

1

-

/

C

C

Vf

f

On

O

FUNCTIONAL DESCRIPTION