MICRF219 datasheet(6/24 Pages) MICREL

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Micrel

MICRF219

Functional Diagram

SYNTHESIZER

CONTROL

LOGIC

IF AMP

LNA

MIXER

CONTROL

LOGIC

January 2009

M9999-011509

(408) 944-0800

NTROL

LOGIC

CONTROL

LOGIC

-f

IMAGE

REJECT

FILTER

DESENSE

DETECTOR

OOK

DEMODULATOR

UHF

DOWNCOVERTER

REFERENCE

AND CONTROL

AUTOPOLL

PROGRAMMABLE

FILTER

BITCHECK

WAKE-UP

SQUELCH

SLEEP

TIMER

SLEEP

OSCILLATOR

REFERENCE

OSCILLATOR

AGC

CONTROL

RSSI

CAGC

CTH

SLICER

SLICE

LEVEL

DO'

fLO

Figure 1.

mplified Block Diagram.

• OOK Demodulator

• Reference and Control logic

• Auto-poll circuitry

Outside the device, the MICRF219 receiver requires just

three components to operate: two capacitors (CTH, and

CAGC) and the reference frequency device (usually a

quartz crystal). An additional five components are used

to improve performance; a power supply decoupling

capacitor, two components for the matching network,

and two components for the pre-selector band-pass

filter.

wnconverter

ix components: LNA,

filter, band pass filter

LNA

The RF input signal is AC-coupled into the gate circuit of

the grounded source LNA input stage. The LNA is a

Cascoded NMOS amplifier. The amplified RF signal is

then fed to the RF ports of two double balanced mixers.

Mixers and Synthesizer

The LO ports of the Mixers are driven by quadrature

local oscillator outputs from the synthesizer block. The

local oscillator signal from the synthesizer is placed on

the low side of the desired RF signal to allow

Functional Description

The simplified block diagram, shown in

illustrates the basic structure of the MICRF21

It is made up of four sub-blocks:

• UHF Down-converter

Figure 1,

Receiver Operation

receiver.

UHF Do

The UHF down-converter has s

mixers, synthesizer, image reject

and IF amp.

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