MAX1470 查看數據表（PDF） - Maxim Integrated

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MAX1470

315MHz Low-Power, +3V Superheterodyne Receiver

Maxim Integrated 

315MHz Low-Power, +3V Superheterodyne

Receiver

PIN

1

2, 7

3

4

5, 10

6

8

9

11, 15, 16,

23, 24

12

13

14

17

18

19

20

21

22

25

26

27

28

Pin Description

NAME

XTAL1

AVDD

LNAIN

LNASRC

AGND

LNAOUT

MIXIN1

MIXIN2

FUNCTION

1st Crystal Input

Positive Analog Supply Voltage for RF Sections. Decouple to AGND with 0.01µF capacitors.

Low-Noise Amplifier Input

Low-Noise Amplifier Source. Connect inductor to ground to set LNA input impedance (see Low-

Noise Amplifier section).

Analog Ground

Low-Noise Amplifier Output

1st Differential Mixer Input. Must be AC-coupled to driving input.

2nd Differential Mixer Input. Must be AC-coupled to driving input.

I.C.

Internally Connected. Do not make connection to these pins.

MIXOUT

DGND

DVDD

IFIN1

IFIN2

DSP

DSN

OPP

DF

DATAOUT

PDOUT

PWRDN

XTAL2

330Ω Mixer Output

Digital Ground

Positive Digital Supply Voltage. Decouple to DGND with a 0.01µF capacitor.

1st Differential Intermediate Frequency Limiter Amplifier Input

2nd Differential Intermediate Frequency Limiter Amplifier Input

Positive Data Slicer Input

Negative Data Slicer Input

Noninverting Op Amp. Input for the Sallen-Key data filter.

Data Filter Feedback Node. Input for the feedback of the Sallen-Key data filter.

Digital Baseband Data Output

Peak Detector Output

Power-Down Select Input. Drive this pin with a logic low to shut down the IC.

2nd Crystal Input

Detailed Description

The MAX1470 CMOS superheterodyne receiver and a

few external components provide the complete receive

chain from the antenna to the digital output data.

Depending on signal power and component selection,

data rates as high as 100kbps can be achieved.

The MAX1470 is designed to receive binary ASK data

on a 315MHz carrier. ASK modulation uses a difference

in amplitude of the carrier to represent logic 0 and logic

1 data.

Low-Noise Amplifier

The LNA is a cascode amplifier with off-chip inductive

degeneration that achieves approximately 16dB of

power gain with a 2.0dB noise figure and an IIP3 of

-18dBm. The gain and noise figure is dependent on

both the antenna matching network at the LNA input,

and the LC tank network between the LNA output and

the mixer inputs.

The off-chip inductive degeneration is achieved by con-

necting an inductor from LNASRC to AGND. This inductor

sets the real part of the input impedance at LNAIN, allow-

ing for a more flexible match for low-input impedance

such as a PC board trace antenna. A nominal value for

this inductor with a 50Ω input impedance is 15nH, but is

affected by PC board trace. See Typical Operating

Characteristics for the relationship between the induc-

tance and input impedance.

The LC tank filter connected to LNAOUT comprises L1

and C9 (see Typical Applications Circuit). L1 and C9 val-

ues are selected to resonate at the RF input frequency of

315MHz. The resonant frequency is given by:

6 _______________________________________________________________________________________

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