MICRF211AYQS Micrel Inc, MICRF211AYQS Datasheet - Page 9

• Manufacturer Part Number: MICRF211AYQS
• Description: IC RX 3V 380-450 MHZ 16-QSOP
• Manufacturer: Micrel Inc

Specifications of MICRF211AYQS

• Operating Temperature: -40°C ~ 105°C
• Frequency: 380MHz ~ 450MHz
• Sensitivity: -110dBm
• Data Rate - Maximum: 10 kbps
• Modulation Or Protocol: ASK, OOK
• Applications: ISM, Garage Door Openers, RKE
• Current - Receiving: 6mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Features: No IF Filter Required
• Voltage - Supply: 3 V ~ 3.6 V
• Package / Case: 16-QSOP
• Data Rate: 1Kbps
• Frequency Range: 380MHz To 450MHz
• Modulation Type: ASK, OOK
• Sensitivity Dbm: -110dBm
• Rf Ic Case Style: QSOP
• No. Of Pins: 16
• Supply Voltage Range: 3V To 3.6V
• Operating Frequency (max): 450000kHz
• Operating Temperature (min): -40C
• Operating Temperature (max): 105C
• Operating Temperature Classification: Industrial
• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (max): 3.6V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Memory Size: -
• Lead Free Status / Rohs Status: Compliant
• Other names: 576-1964-5; MICRF211AYQS

March 2007
Micrel
For the frequency of 433.92MHz, the input impedance
is Z = 18.6 – j174.2Ω, then the matching components
are calculated by,
Equivalent parallel = B = 1/Z = 0.606 + j5.68 msiemens
Rp = 1 / Re (B);
Rp = 1.65kΩ;
Q = SQRT (Rp/50 + 1)
Q = 5.831
Xm = Rp / Q
Xm = 282.98Ω
Resonance Method For L-shape Matching Network
Lc = Xp / (2×Pi×f);
L2 = (Lc×Lp) / (Lc + Lp);
L2 = 39.8nH
C3 = 1.3pF
Doing the same calculation example with the Smith
Chart, it would appear as follows,
First, we plot the input impedance of the device,
(Z = 18.6 – j174.2)Ω @ 433.92MHz.(Figure 4).
Table 4: matching values for the most used frequencies
Freq (MHz)
390.0
418.0
433.92
Xp = 176.2Ω
C3 (pF)
1.5
1.5
1.5
L2(nH)
47
43
39
Xp = 1 / Im (B)
Lp = Xm / (2×Pi×f)
C3 = 1 / (2×Pi×f×Xm)
22.5 – j198.5
21.4 – j186.1
18.6 – j174.2
Z device (Ω)
9
Second, we plot the shunt inductor (39nH) and the
series capacitor (1.5pF) for the desired input
impedance (Figure 5). We can see the matching
leading to the center of the Smith Chart or close to
50Ω.
Figure 4: device’s input impedance, Z = 18.6 – j174.2Ω
Figure 5. Plotting the Shunt Inductor and Series
Capacitor.
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M9999-030107
MICRF211