TRF5901

SINGLE-CHIP RF TRANSCEIVER

SWRS014 – DECEMBER 2002

10

POST OFFICE BOX 655303

tw(CLKHI)

CLOCK

DATA

STROBE

tsu(DATA)

th(DATA)

tw(STROBEHI)

tw(STROBELO)

tw(CLKLO)

Figure 2. Serial Data Interface Timing

detailed description

low-noise amplifier

The low-noise amplifier (LNA) provides a typical gain of 13 dB and a typical noise figure of 3.3 dB.

Two operating modes, normal and low-gain mode, can be selected. The normal operation mode is selected

when maximum sensitivity at low input levels is required. If high RF input levels are applied to the TRF5901,

the LNA should be operated in the low-gain mode. This ensures a minimum of nonlinear distortions in the overall

receiver chain.

Figure 3. Typical LNA Input Impedance (S11)

at Device Terminal LNA_IN

Figure 4. Typical LNA Output Impedance

(S22) at Device Terminal LNA_OUT

0.5

1

↑1 U

2

5

10

2

1

0.5

0.2

0

–0.5

–1

–2

–5

START 850 MHz

STOP 950 MHz

CH1 S11

CAL

OFS

CPL

FIL

1k

↑1 U

START 850 MHz

STOP 950 MHz

CH1 S22

CAL

OFS

CPL

FIL

1k

1

1

5

0.5

1

2

5

10

2

1

0.5

0.2

0

–0.5

–1

–2

–5

5

The low impedance of the LNA input can be easily matched to 50

Ω to interface with a filter or an RF switch.

At the LNA open collector output, a filter network can be used for image suppression as well as impedance

matching.