PRELIMINARY
CYWUSB6941
Document #: 38-16004 Rev. *A
Page 3 of 14
3.0
Functional Overview
The Cypress CYWUSB6941 WirelessUSB EX transceiver is designed to work with the Cypress CYWUSB6942 WirelessUSB EX
baseband controller to provide a complete WirelessUSB EX solution. The CYWUSB6941 contains a 2.4-GHz radio transceiver,
a GFSK modem, and a radio control interface that communicates with the CYWUSB6942 WirelessUSB EX baseband. The
CYWUSB6941 also facilitates the development of a complete WirelessUSB EX system with a minimum number of additional
components, typically requiring only eight external components (including crystal) for ease of implementation and manufacturing
(refer to Figure 3-1). Specific features include:
• 2.4-GHz frequency-hopping spread spectrum (FHSS) transceiver
• GFSK modulator/demodulator
• No external transmit/receive switch required
• Minimizes the need for external components
• Closed-loop phase-locked loop (PLL)
• VCO is integrated in the CYWUSB6941
• No external loop circuitry required
• Radio control interface.
3.1
2.4-GHz Radio Transceiver and GFSK Modem
The receiver is a low-IF architecture with fully integrated IF filters to achieve high performance in the presence of interference.
The FM demodulator and fast data slicer are fully integrated.
The hop frequency synthesizer provides the frequency-hopping local oscillator for the transmitter and receiver. The only external
components required are reference crystal, and several capacitors. The RF VCO is fully integrated, requiring no external tank
circuits.
The transmitter uses a DSP-based vector modulator to convert the transmit data to an accurate GFSK-modulated carrier. There
are a variety of DC power control features for transmitter, synthesizer, and receiver functions to optimize the average current drain.
3.2
Clocking
The CYWUSB6941 requires an external 13-MHz crystal with the following characteristics:
• Crystal temperature stability:
± 15 ppm max
• Crystal load capacitance: 10 – 15 pF.
The crystal has to be placed across the X13IN and X13 pins. No extra capacitors are needed.