MAX2370 datasheet(6/19 Pages) MAXIM

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Complete 450MHz Quadrature Transmitter

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Pin Description

NAME

FUNCTION

RFOUT

Transmitter RF Output. This open-collector output requires a pullup inductor to the supply voltage,

which can be part of the output matching network.

2, 10, 11, 16,

17, 32–35,

43, 47

N.C.

No Connection. Leave these pins open-circuit. Some of these pins are internally connected.

3LOCK

Open-Drain Output Indicating LOCK Status of the IF and/or the RF PLLs. Requires an external

pullup resistor. Control using configuration register bits LD_MODE[1:0].

4VCCDRV

Power Supply for the RF Driver Stage. Bypass to PC board ground with a capacitor placed as

close to the pin as possible. Do not share capacitor ground vias with other ground connections.

IDLE

Digital Input. Drive to logic-high for normal operation. Logic-low on IDLE shuts down everything

except the RF PLL. A small RC lowpass filter can be used to filter digital noise.

6VCC

Power Supply for the Upconverter Stage. Bypass to PC board ground with a capacitor placed as

close to the pin as possible. Do not share capacitor ground vias with other ground connections.

TXGATE

Digital Input. Drive to logic-high for normal operation. Logic-low on TXGATE shuts down everything

except the RF PLL, IF PLL, IF VCO. A small RC lowpass can be used to filter digital noise.

8, 9

IFIN+, IFIN-

Differential IF Inputs to the RF Upconverter. IFIN+ and IFIN- are internally biased to typically VCC -

1.5V. The input impedance for this port is nominally 400

Ω differential. AC-couple the output of the

differential IF filter to this port. Keep the differential lines as short as possible to minimize the

effects of stray pickup.

RBIAS

Bias Resistor Connection. Internally biased to typically 1.18V. An external resistor must be

connected from RBIAS to ground to set the bias current for the upconverters and PA driver

stages. The nominal resistor value is 10k

Ω. This value can be altered to optimize the linearity of

the driver stage.

Typical Operating Characteristics (continued)

(MAX2370 EV kit, VCC_ = SHDN = IDLE = TXGATE = CS = 3.0V, fREF = 19.2MHz, LO input power = -15dBm, fLO = 575MHz, fRFOUT =

455MHz, fIF = 120MHz, RBIAS = 10k

Ω, VGC = 2.5V, registers set according to Table 1, input voltage at I and Q = 130mVRMS differential,

TA = +25°C, unless otherwise noted.)

-90

-70

-80

-50

-60

-30

-40

-20

-10

FREQUENCY

RF OUTPUT SPECTRUM

POUT = +8dBm

CENTER: 455MHz, SPAN: 5MHz, RBW: 30kHz

-100

-80

-90

-60

-70

-50

-40

-20

-30

-10

239.8

239.9

240.0

240.1

240.2

240.3

IF LOCAL OSCILLATOR SPECTRUM

FREQUENCY (MHz)

PREF = -10dBm

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