STB5701 datasheet(17/35 Pages) STMICROELECTRONICS

17 / 35 page

STB5701

Functional description

17/35

Functional description

4.1

General description

The STB5701 FSK/ASK receiver is a heterodyne configuration (10.7 MHz IF Frequency)

and it is designed for applications in the 350MHz to 400MHz frequency range and includes

ASK and FSK detectors. The synthesizer has a typical channel spacing of better than 100

kHz and uses a integrated fully VCO. With the STB5701 receiver chip, various circuit

configurations can be arranged in order to meet a number of different customer

requirement.

The STB5701 is housed in a VQF package 5mm x 5mm 32 leads.

The STB5701 receiver IC consists of the following building blocks:

●

Phase Locked Loop Synthesizer (PLL): M-Counter, A-Counter, Prescaler, Phase-

Frequency Detector (PFD), Charge Pump (CP), Voltage Controlled Oscillator (VCO).

●

Programmable reference divider for crystal and channel step selection.

●

Low Noise Amplifier (LNA) with AGC function for high sensitivity and dynamic range RF

signal reception.

●

Image Rejection Mixer for down conversion of the RF signal to the IF (without external

saw image filter).

●

IF amplifier to amplify and limit the IF signal and for RSSI generation.

●

Phase coincidence demodulator to demodulate the IF signal.

●

Operation amplifier for data slicing, filtering and ASK detection.

●

Min/max peak detector to create a DC output voltage equal to the mean of the min and

max peak value of the data signal.

●

I2C bus to exchange data between the STB5701 and the micro.

●

Start code detector (SCD) to recognize a valid data signal to prevent continuos toggling

of data in the absence of an RF Signal due to the noise.

●

Bias circuitry for band gap biasing and circuit shutdown.

STB5701 Datasheet(PDF) 17 Page - STMicroelectronics