ML5805
provided. RSSI (an indication of field strength) can be used by the system to determine transmit power control
(conserve battery life) and/or to determine if a given channel is occupied.
AUTOMATIC VCO AND FILTER ALIGNMENT
The VCO and IF filters are calibrated to remove process and temperature variation. IF filter and VCO calibration occurs
when the chip is first powered on and at specified intervals during normal operation. This calibration is transparent to
the normal operation of the ML5805 and is absorbed in the system timing shown in Figure 2 and Table 2. This self-
calibration adjusts:
VCO center frequency
Discriminator center frequency
IF filter center frequency and bandwidth
Receiver data low-pass filter bandwidth
TRANSMITTER AND PA
The ML5805 transmitter consists of an up-conversion mixer followed by a programmable gain amplifier to allow factory
calibration of the output power, and finally a power amplifier (PA). The input data is filtered before being sent to an
adjustment free VCO modulator. An FIR Gaussian pulse shaping filter is used followed by DAC and interpolation filter
for clock rejection. The output of modulator is up-converted by a mixer and amplified with a PA to deliver 21dBm output
power. A complementary T/R switch control output with adjustable timing is provided to control the external T/R switch.
PLL/SYNTHESIZER
A single, on-chip 3.9GHz fractional-N synthesizer is used to generate the receiver LO and transmit carrier. The VCO
has an on chip resonator, active devices and tuning circuitry for a completely integrated VCO function. All required DC
voltage regulation is within the IC. The PLL center frequency is programmed with a 23 bit word written via the SPI port
during either standby or active operation.
A lock detect circuit monitors the state of the PLL loop allowing the PA to be disabled prior to the PLL achieving lock in
TRANSMIT mode. In RECEIVE mode, the synthesizer produces a low side LO frequency offset (compared to TX mode)
to produce the required IF frequency.
MODES OF OPERATION
The ML5805 has three key modes of operation:
STANDBY:
RECEIVE:
TRANSMIT:
All circuits powered down, except the control interface (static CMOS)
Receiver circuits active
Transmitter circuits active
MODE CONTROL
The two operational modes controlled by RXON are RECEIVE and TRANSMIT. XCEN is the chip enable/disable control
pin, which sets the device to either operational or STANDBY modes. The relationship between the parallel control lines
and the mode of operation of the IC is summarized in Table 1.
XCEN
RXON
MODE NAME
FUNCTION
0
1
1
X
1
0
STANDBY
RECEIVE
TRANSMIT
Control interfaces active, all other circuits powered down
Receiver time slot
Transmit time slot
Table 1: Modes of Operation
RF MICRO DEVICES®, RFMD®, OPTIMUM TECHNOLOGY MATCHING®, ENABLING WIRELESS CONNECTIVITY™, POWERSTAR®, POLARIS™ TOTAL RADIO™ ULTIMATEBLUE™ AND FASTWAVE™ ARE TRADEMARKS OF RFMD, LLC. BLUETOOTH IS A TRADEMARK OWNED BY
BLUETOOTH SIG, INC., U.S.A. AND LICENSED FOR USE BY RFMD. ALL OTHER TRADE NAMES, TRADEMARKS AND REGISTERED TRADEMARKS ARE THE PROPERTY OF THEIR RESPECTIVE OWNERS. ©2006, RF MICRO DEVICES, INC.
PRELIMINARY DATA SHEET
APRIL 2008
EDS-106041 REV P01
7628 THORNDIKE ROAD, GREENSBORO, NC 27409-9421 · FOR SALES OR TECHNICAL
REV A1 DS071026 SUPPORT, CONTACT RFMD AT (+1) 336-678-5570 OR SALES-SUPPORT@RFMD.COM
13
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