MICRF221 データシートの表示（PDF） - Micrel

部品番号

コンポーネント説明

メーカー

MICRF221

3.3V, QwikRadio® 850 MHz to 950 MHz Receiver

Micrel 

Micrel Inc.

Functional Diagram

MICRF221

UHF

DOWNCOVERTER

MIXER

LNA

MIXER

fLO

SYNTHESIZER

-f f

i

IMAGE

REJECT

FILTER

CONTROL

LOGIC

DESENSE

IF AMP

DETECTOR

CONTROL

LOGIC PROGRAMMABLE

FILTER

AGC

CONTROL

CAGC

RSSI

OOK

DEMODULATOR

SLICER

RSSI

SLEEP

OSCILLATOR

SLEEP

TIMER

AUTOPOLL

DO

REFERENCE

OSCILLATOR

REFERENCE

AND CONTROL

BITCHECK

WAKE-UP

SQUELCH

DO' CONTROL

LOGIC

DO'

SLICE

LEVEL

CONTROL

LOGIC

DO

CTH

Figure 3. Simplified Block Diagram

Functional Description

The simplified block diagram, shown in Figure 3,

illustrates the basic structure of the MICRF221

receiver. It is made of four sub-blocks:

• UHF Down-converter

• OOK Demodulator

• Reference and Control logic

• Auto-poll circuitry.

Outside the device, the MICRF221 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

October 2008

pre-selector band-pass filter.

Receiver Operation

UHF Downconverter

The UHF down-converter has six components: LNA,

mixers, synthesizer, image reject filter, band pass filter

and IF amp.

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.

7

M9999-100108

(408) 955-1690

Share Link: