CT266
.
Pin Description
Pin
Name
Description
This is a highly efficient output buffer of the VCO. Normally, it can be directly connected to a
filter network for antenna matching purposes and to also reduce unwanted harmonics. See
output power versus power supply voltage in Figure 1.
2
Fout
SB
The standby pin is used to save power consumption when not using transmit signal Output
power. When it is low, the VCO is disabled, the chip has zero power consumption. This pin
has an internal pull-down.
3
These are input and output of the VCO.
They are typically connected to a varactor and respective LC network to provide a tuned VCO
circuit that operates between 46 MHz and 49 MHz. See Figure 2 for circuit details.
4
5
VCOin
VCOut
7
1
VSS
VDD
Circuit ground pin.
Positive power supply pins (2.0V~5V).
This is a highly efficient output buffer of the VCO. Normally, it can be directly connected to a filter
network for antenna matching purposes and to also reduce unwanted harmonics. See output
power versus power supply voltage in Figure 1.
2
6
8
Fout
VDD
STP
Transmit power cut-off control pin. When it is HIGH, transmit power is in standby. It can be
controlled by lock detection (LD) of PLL frequency synthesizer to monitor transmit power of an
out-of-lock condition. It has an internal pull-down resistor.
Application Figures
Po (mW @ RL = 50 ohm)
16mW
15
10
5
13mW
9.5mW
7.0mW
4.0mW
2.5mW
1
1mW
VDD(V)
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Figure 1. Transmit Power vs. Supply Voltage
Document #: 38-07341 Rev. **
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