MC13175D View Datasheet(PDF) - Motorola => Freescale

Part Name

Description

Manufacturer

MC13175D

UHF FM/AM TRANSMITTER

Motorola => Freescale 

MC13175 MC13176

Figure 26. ASK Input Waveform and Modulated Carrier

Pin 16

OOK Input Modulation

10 kHz TTL Waveform

On–Off Keying Encoded

Carrier Envelope

Figure 27. Oscillator Enable Time, Tenable

Pin 8

Oscillator Waveform

Figure 28. Power Output versus Modulation Current

10

5.0

0

– 5.0

VCC = 3.0 Vdc

f = 320 MHz

–10

–15

– 20

– 25

0.1

1.0

10

Imod, MODULATION CURRENT (mA)

Analog AM

In analog AM applications, the output amplifier’s linearity

must be carefully considered. Figure 28 is a plot of Power

Output versus Modulation Current at 320 MHz, 3.0 Vdc. In

order to achieve a linear encoding of the modulating

sinusoidal waveform on the carrier, the modulating signal

must amplitude modulate the carrier in the linear portion of its

power output response. When using a sinewave modulating

signal, the signal rides on a positive DC offset called Vmod

which sets a static (modulation off) modulation current, Imod.

Imod controls the power output of the IC. As the modulating

signal moves around this static bias point the modulating

current varies causing power output to vary or to be AM

modulated. When the IC is operated at modulation current

levels greater than 2.0 mAdc the differential output stage

starts to saturate.

MOTOROLA RF/IF DEVICE DATA

15

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