21
iO1000 Detailed Service Manual - THEORY OF OPERATION
ODCT ASIC Offset VCO
The offset VCO is a discrete VCO that is controlled by the offset synthesizer in the
iZIF. The frequency of the offset VCO is 301.8 MHz which is divided by two to
150.9 MHz in the ODCT and mixed with the main VCO to generate the transmit
frequency.
Transceiver Circuitry
All the transceiver circuitry is located on the main board. This board is divided
into the following sections:
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Global Control Audio Power II (GCAP II) circuitry
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DC voltage distribution
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Audio circuitry
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Digital (REDCAP and associated circuitry)
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Transmitter path
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Receiver path
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Frequency generating (RF)
The keypad contains the high-audio speaker, microphone, and keypad circuitry.
Global Control Audio Power II (GCAP II) Circuitry
The GCAP II integrated circuit (IC) contains the following:
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Two BUCK/BOOST switching power supplies
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2.775Vdc/5.0Vdc regulator
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3.0Vdc/5.0Vdc regulator
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Linear 2.775Vdc to 3.6Vdc regulator in 8 steps
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Linear 2.775Vdc to 1.8Vdc regulator in 8 steps
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2.775Vdc to 3.6Vdc low-current reference
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Analog/digital portions of a real-time clock (RTC)
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Charge pump output
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Power amplifier (PA) high-end regulator adjustable in 16 steps
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Battery charger
