MAX2510 Ver la hoja de datos (PDF) - Maxim Integrated

Número de pieza

componentes Descripción

Lista de partido

MAX2510

Low-Voltage IF Transceiver with Limiter/RSSI and Quadrature Modulator

Maxim Integrated 

Low-Voltage IF Transceiver with

Limiter/RSSI and Quadrature Modulator

Received Signal-Strength Indicator

The RSSI output provides a linear indication of the

received power level on the LIMIN input. The RSSI

monotonic dynamic range exceeds 90dB while provid-

ing better than 80dB linear range. The RSSI output

pulses current into a 330pF (typical) external filter

capacitor. The output is internally terminated to ground

with 11kΩ, and this R-C time constant sets the decay

time. The rise time is limited by the RSSI pin’s output

drive current. The rise time is typically less than 100ns

with no capacitor connected. Larger capacitor values

slow the rise time.

Transmitter

The I, I and Q, Q baseband signals are input to a pair

of double-balanced mixers, which are driven from a

quadrature LO source. The quadrature LO is generated

on-chip from the oscillator input present at the LO and

LO pins. The two mixers’ outputs are summed. With

quadrature baseband inputs at the I, I and Q, Q pins,

the unwanted sideband is largely canceled. The result-

ing signal from the mixers is fed through a variable-gain

amplifier (VGA) with more than 40dB of gain-adjust

range.

The VGA output is connected to a driver amplifier with

an output 1dB compression point of +2dBm. The out-

put power can be adjusted from approximately +2dBm

to -40dBm by controlling the GC pin. The resulting sig-

nal appears as a differential output on the TXOUT and

TXOUT pins.

TXOUT and TXOUT are open-collector outputs and

need external pull-up inductors to VCC for proper oper-

ation, as well as a DC block so the load does not affect

DC biasing. A shunt resistor across TXOUT and TXOUT

(100Ω typical) can be used to back terminate an exter-

nal filter, as shown in the Typical Operating Circuit.

Alternatively, a single-ended load can be connected to

TXOUT, as long as TXOUT is tied directly to VCC. Refer

to the Applications Information section for details.

Local-Oscillator Inputs

The MAX2510 requires an external LO source for the

mixers. LO and LO are high-impedance inputs (>1kΩ).

The external LO signal is buffered internally and fed to

both the receive mixer and the LO phase shifter used

for the transmit mixers.

In a typical application, externally terminate the LO

source with a 50Ω resistor and then AC couple into LO.

Typically, the LO power range should be -13dBm to

0dBm (into 50Ω). Connect a bypass capacitor from LO

to ground. Alternatively, a differential LO source (exter-

nally terminated) can drive LO and LO through series

coupling capacitors.

Power Management

To provide advanced system power management, the

MAX2510 features four operating modes that are

selected via the RXEN and TXEN pins, according to

Table 1 (supply currents assume GC = 0.5V).

In shutdown mode, all part functions are off. Standby

mode allows fastest enabling of either transmit or receive

mode by keeping the VREF generator active. This avoids

delays in stabilizing the limiter input circuitry and the off-

set correction loop. Transmit mode enables the LO

buffer, LO phase shifter, upconverter mixer, transmit

VGA, and transmit output driver amplifier. Receive mode

enables the LO buffer, downconverter mixer, limiting

amplifier, and RSSI functions.

Table 1. Power-Supply Mode Selection

RXEN

STATE

Low

Low

High

High

TXEN

STATE

Low

High

Low

High

MODE

Shutdown

Transmit

Receive

Standby

TYPICAL

SUPPLY

CURRENT (A)

0.2µ

17m

14m

0.5m

__________Applications Information

RX Input Matching

The RXIN, RXIN port typically needs an impedance

matching network for proper connection to external cir-

cuitry, such as a filter. See the Typical Operating Circuit

for an example circuit topology. Note that the receiver

input can be driven either single-ended or differentially.

The component values used in the matching network

depend on the desired operating frequency as well as

on filter impedance. The following table indicates the

RXIN, RXIN single-ended input impedance (that is,

the impedance looking into either RXIN or RXIN). The

information in Table 2 is also plotted in the Typical

Operating Characteristics.

10 ______________________________________________________________________________________

Share Link: